1 Strength training is as effective as stretching for improving ...

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Strength training is as effective as stretching for improving range of motion: A systematic 1

review and meta-analysis. 2

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José Afonso, Ph.D. 1*, Rodrigo Ramirez-Campillo, Ph.D. 2,3, João Moscão4, Tiago Rocha, 4

M.Sc. 5, Rodrigo Zacca, Ph.D. 1,6,7, Alexandre Martins, B.Sc. 1, André A. Milheiro, M.Sc.1, 5

João Ferreira, B.Sc. 8, Hugo Sarmento, Ph.D. 9, Filipe Manuel Clemente, Ph.D. 10,11 6

7 1 Centre for Research, Education, Innovation and Intervention in Sport, Faculty of Sport of the University of Porto. 8

Rua Dr. Plácido Costa, 91, 4200-450 Porto, Portugal. 9 2 Department of Physical Activity Sciences. Universidad de Los Lagos. Lord Cochrane 1046, Osorno, Chile. 10 3 Centro de Investigación en Fisiología del Ejercicio. Facultad de Ciencias. Universidad Mayor. San Pio X, 2422, 11

Providencia, Santiago, Chile. 12 4 REP Exercise Institute. Rua Manuel Francisco 75-A 2º C 2645-558 Alcabideche, Portugal. 13 5 Polytechnic of Leiria, Rua General Norton de Matos, Apartado 4133, 2411-901 Leiria, Portugal. 14 6 Porto Biomechanics Laboratory (LABIOMEP), University of Porto, Rua Dr. Plácido Costa, 91, 4200-450 Porto, 15

Portugal. 16 7 Coordination for the Improvement of Higher Educational Personnel Foundation (CAPES), Ministry of Education 17

of Brazil, Brasília, Brazil. 18 8 Superior Institute of Engineering of Porto, Polytechnic Institute of Porto. Rua Dr. António Bernardino de 19

Almeida, 431, 4249-015 Porto, Portugal. 20 9 Faculty of Sport Sciences and Physical Education, University of Coimbra, 3040-256, Coimbra, Portugal. 21 10 Escola Superior Desporto e Lazer, Instituto Politécnico de Viana do Castelo, Rua Escola Industrial e Comercial 22

de Nun’Álvares, 4900-347, Viana do Castelo, Portugal. 23 11 Instituto de Telecomunicações, Department of Covilhã, 1049-001, Lisboa, Portugal. 24

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*Corresponding author: José Afonso | [email protected]. 26

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Summary box 30

What is already known? 31

• Stretching is effective for improving in range of motion (ROM), but promising findings 32

have suggested that strength training also generates ROM gains. 33

34

What are the new findings? 35

• Strength training seems to be as effective as stretching in generating ROM gains. 36

• In contradiction with existing guidelines, stretching is not strictly necessary for improving 37

ROM, as strength may provide an equally valid alternative. 38

• These findings were consistent across studies, regardless of the characteristics of the 39

population and of the specificities of strength training and stretching programs. 40

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ABSTRACT 44

Background: Range of motion (ROM) is an important feature of sports performance and 45

health. Stretching is usually prescribed to improve promote ROM gains, but evidence has 46

suggested that strength training (ST) also improves ROM. However, it is unclear if its efficacy 47

is comparable to stretching. Objective: To perform a systematic review and meta-analysis of 48

randomized controlled trials (RCTs) assessing the effects of ST and stretching on ROM. 49

Protocol: INPLASY: 10.37766/inplasy2020.9.0098. Data sources: Cochrane Library, 50

EBSCO, PubMed, Scielo, Scopus, and Web of Science were consulted in early October 2020, 51

followed by search within reference lists and consultation of four experts. No constraints on 52

language or year. Eligibility criteria (PICOS): (P) humans of any sex, age, health or training 53

status; (I) ST interventions; (C) stretching interventions (O) ROM; (S) supervised RCTs. Data 54

extraction and synthesis: Independently conducted by multiple authors. Quality of evidence 55

assessed using GRADE; risk-of-bias assessed with RoB 2. Results: Eleven articles (n = 452 56

participants) were included. Pooled data showed no differences between ST and stretching on 57

ROM (ES = -0×22; 95% CI = -0×55 to 0×12; p = 0×206). Sub-group analyses based on RoB, 58

active vs. passive ROM, and specific movement-per-joint analyses for hip flexion and knee 59

extension showed no between-protocol differences in ROM gains. Conclusion: ST and 60

stretching were not different in improving ROM, regardless of the diversity of protocols and 61

populations. Barring specific contra-indications, people who do not respond well or do not 62

adhere to stretching protocols can change to ST programs, and vice-versa. 63

64

KEYWORDS: systematic review; meta-analysis; strength training; flexibility; stretching; 65

range of motion. 66

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Introduction 70

Improving range of motion (ROM) is a core goal for the general population,[1] as well 71

as in clinical contexts,[2] such as when treating acute respiratory failure,[3] plexiform 72

neurofibromas,[4] and total hip replacement.[5] Unsurprisingly, ROM gains are also relevant 73

in different sports,[6] such as basketball, baseball and rowing,[7-9] among others. ROM is 74

improved through increased stretch tolerance, augmented fascicle length and changes in 75

pennation angle,[10] as well as reduced tonic reflex activity.[11] Stretching is usually 76

prescribed to increase ROM in sports,[12, 13] clinical settings such as chronic low back 77

pain,[14] rheumatoid arthritis,[15] and exercise performance in general.[16] Stretching 78

techniques include static (active or passive), dynamic, or proprioceptive neuromuscular 79

facilitation (PNF), all of which can improve ROM.[1, 17-20] 80

However, reduced ROM and muscle weakness are deeply associated.[21-23] Therefore, 81

although strength training (ST) primarily addresses muscle weakness through methods such as 82

resistance training or similar protocols, it has been shown to increase ROM in athletic 83

populations,[24, 25] as well as in healthy elderly people[26] and women with chronic 84

nonspecific neck pain.[27] ST focused on concentric and eccentric contractions has been 85

shown to increase fascicle length. [28-30] Better agonist-antagonist co-activation[31], 86

reciprocal inhibition,[32] and adjusted stretch-shortening cycles[33] may also explain why ST 87

is a suitable method for improving ROM. 88

Nevertheless, studies comparing the effects of ST and stretching in ROM have 89

presented conflicting evidence,[34, 35] and many have small sample sizes.[36, 37] Developing 90

a systematic review and meta-analysis (SRMA) may help summarize this conflicting evidence 91

and increase statistical power, thus providing clearer guidance for interventions.[38] Therefore, 92

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the aim of this SRMA was to compare the effects of supervised and randomized ST versus 93

stretching protocols on ROM in participants of any health and training status. 94

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METHODS 97

Protocol and registration 98

The methods and protocol registration were preregistered prior to conducting the 99

review: INPLASY, no.202090098, DOI: 10.37766/inplasy2020.9.0098. 100

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Eligibility criteria 102

Articles were eligible for inclusion if published in peer-reviewed journals, with no 103

restrictions in language or publication date. The Preferred Reporting Items for Systematic 104

Reviews and Meta-Analyses (PRISMA) guidelines were adopted.[39] Participants, 105

interventions, comparators, outcomes, and study design (P.I.C.O.S.) were established as 106

follows: (i) participants with no restriction regarding health, sex, age, or training status; (ii) ST 107

interventions supervised by a certified professional, using resistance training or similar 108

protocols; (iii) comparators were supervised groups performing any form of stretching (iv) 109

outcomes were ROM assessed in any joint; (v) randomized controlled trials (RCTs). RCTs 110

reduce bias and better balance participant features between the groups,[38] and are important 111

for the advancement of sports science.[40] There were no limitations regarding intervention 112

length. 113

Reviews, letters to editors, trial registrations, proposals for protocols, editorials, book 114

chapters, and conference abstracts were excluded. Exclusion criteria based on P.I.C.O.S.: (i) 115

research with non-human animals; (ii) non-ST protocols or ST interventions combined with 116

other methods (e.g., endurance); unsupervised interventions; (iii) stretching or ST + stretching 117

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interventions combined with other training methods (e.g., endurance); protocols without 118

stretching; unsupervised interventions; (iv) studies not reporting ROM; (v) non-randomized 119

interventions. 120

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Information sources and search 122

Six databases were used to search and retrieve the articles in early October 2020: 123

Cochrane Library, EBSCO, PubMed (including MEDLINE), Scielo, Scopus, and Web of 124

Science (Core Collection). Boolean operators were applied to search the article title, abstract 125

and/or keywords: (“strength training” OR “resistance training” OR “weight training” OR 126

“plyometric*” OR “calisthenics”) AND (“flexibility” OR “stretching”) AND “range of 127

motion” AND “random*”. Specificities of each search engine: (i) in Cochrane Library, items 128

were limited to trials, including articles but excluding protocols, reviews, editorials and similar 129

publications; (ii) in EBSCO, the search was limited to articles in scientific, peer-reviewed 130

journals (iii) in PubMed, the search was limited to title or abstract; publications were limited 131

to RCTs and clinical trials, excluding books and documents, meta-analyses, reviews and 132

systematic reviews; (iv) in Scielo, Scopus and Web of Science, the publication type was limited 133

to article; and (v) in Web of Science, “topic” is the term used to refer to title, abstract and 134

keywords. 135

An additional search within the reference lists of the included records was conducted. 136

The list of articles and inclusion criteria were then sent to four experts to suggest additional 137

references. The search strategy and consulted databases were not provided in this process to 138

avoid biasing the experts’ searches. More detailed information is available as supplementary 139

material. 140

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Search strategy 142

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Here, we provide the specific example of search conducted in PubMed: 143

((("strength training"[Title/Abstract] OR "resistance training"[Title/Abstract] OR 144

"weight training"[Title/Abstract] OR "plyometric*"[Title/Abstract] OR 145

"calisthenics"[Title/Abstract]) AND (“flexibility”[Title/Abstract] OR 146

“stretching”[Title/Abstract])) AND (“range of motion”[Title/Abstract])) AND 147

(“random*”[Title/Abstract]). 148

After this search, the filters RCT and Clinical Trial were applied. 149

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Study selection 151

J.A. and F.M.C. each conducted the initial search and selection stages independently, 152

and then compared result to ensure accuracy. J.F. and T.R. independently reviewed the process 153

to detect potential errors. When necessary, re-analysis was conducted until a consensus was 154

achieved. 155

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Data collection process 157

J.A., F.M.C., A.A.M. and J.F. extracted data, while J.M., T.R., R.Z. and A.M. 158

independently revised the process. Data for the meta-analysis was extracted by JA and 159

independently verified by A.A.M. and R.R.C. Data is available for sharing. 160

161

Data items 162

Data items: (i) Population: subjects, health status, sex/gender, age, training status, 163

selection of subjects; (ii) Intervention and comparators: study length in weeks, weekly 164

frequency of the sessions, weekly training volume in minutes, session duration in minutes, 165

number of exercises per session, number of sets and repetitions per exercise, load (e.g., % 166

1RM), full vs. partial ROM, supervision ratio; in the comparators, modality of stretching 167

applied was also considered; adherence rates were considered a posteriori; (iii) ROM testing: 168

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joints and actions, body positions (e.g., standing, supine), mode of testing (i.e., active, passive, 169

both), pre-testing warm-up, timing (e.g., pre- and post-intervention, intermediate assessments), 170

results considered for a given test (e.g., average of three measures), data reliability, number of 171

testers and instructions provided during testing; (iv) Outcomes: changes in ROM for 172

intervention and comparator groups; (vi) funding and conflicts of interest. 173

174

Risk of bias in individual studies 175

Risk of bias (RoB) in individual studies was assessed using the Cochrane risk-of-bias 176

tool for randomized trials (RoB 2).[41] J.A. and A.M. independently completed RoB analysis, 177

which was reviewed by F.M.C. Where inconsistencies emerged, the original articles were re-178

analyzed until a consensus was achieved. 179

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Summary measures 181

Meta-analysis was conducted when ≥3 studies were available.[42] Pre- and post-182

intervention means and standard deviations (SDs) for dependent variables were used after 183

being converted to Hedges’s g effect size (ES).[42] When means and SDs were not available, 184

they were calculated from 95% confidence intervals (CIs) or standard error of mean (SEM), 185

using Cochrane’s RevMan Calculator for Microsoft Excel.[43] When ROM data from different 186

groups (e.g. men and women) or different joints (e.g. knee and ankle) was pooled, weighted 187

formulas were applied.[38] 188

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Synthesis of results 190

The inverse variance random-effects model for meta-analyses was used to allocate a 191

proportionate weight to trials based on the size of their individual standard errors,[44] and 192

accounting for heterogeneity across studies.[45] The ESs were presented alongside 95% CIs 193

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and interpreted using the following thresholds:[46] <0×2, trivial; 0×2–0×6, small; >0×6–1×2, 194

moderate; >1×2–2×0, large; >2×0–4×0, very large; >4×0, extremely large. Heterogeneity was 195

assessed using the I2 statistic, with values of <25%, 25-75%, and >75% considered to represent 196

low, moderate, and high levels of heterogeneity, respectively.[47] 197

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Risk of bias across studies 199

Publication bias was explored using the extended Egger’s test,[48] with p<0×05 200

implying bias. To adjust for publication bias, a sensitivity analysis was conducted using the 201

trim and fill method,[49] with L0 as the default estimator for the number of missing studies.[50] 202

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Moderator analyses 204

Using a random-effects model and independent computed single factor analysis, 205

potential sources of heterogeneity likely to influence the effects of training interventions were 206

selected, including i) ROM type (i.e., passive vs active), ii) studies RoB in randomization and 207

iii) studies RoB in measurement of the outcome.[51] These analyses were decided post-208

protocol registration. 209

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All analyses were carried out using the Comprehensive Meta-Analysis program 211

(version 2; Biostat, Englewood, NJ, USA). Statistical significance was set at p≤0×05. Data for 212

the meta-analysis was extracted by JA and independently verified by A.A.M. and R.R.C. 213

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Quality and confidence in findings 215

Although not planned in the registered protocol, we decided to abide by the Grading of 216

Recommendations Assessment, Development, and Evaluation (GRADE),[52] which addresses 217

five dimensions that can downgrade studies when assessing the quality of evidence in RCTs. 218

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RoB, inconsistency (through heterogeneity measures), and publication bias were addressed 219

above and were considered a priori. Directness was guaranteed by design, as no surrogates 220

were used for any of the pre-defined P.I.C.O. dimensions. Imprecision was assessed on the 221

basis of 95% CIs. 222

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RESULTS 225

Study selection 226

Initial search returned 194 results (52 in Cochrane Library, 11 in EBSCO, 11 in 227

PubMed, 9 in Scielo, 88 in Scopus, and 23 in Web of Science). After removal of duplicates, 228

121 records remained. Screening the titles and abstracts for eligibility criteria resulted in the 229

exclusion of 106 articles: 26 were not original research articles (e.g., trial registrations, 230

reviews), 24 were out of scope, 48 did not have the required intervention or comparators, five 231

did not assess ROM, two were non-randomized and one was unsupervised. Fifteen articles 232

were eligible for full-text analysis. One article did not have the required intervention,[53] and 233

two did not have the needed comparators.[54, 55] In one article, the ST and stretching groups 234

performed a 20-30 minutes warm-up following an unspecified protocol.[56] In another, the 235

intervention and comparator were unsupervised[57], and in one the stretching group was 236

unsupervised[58]. Finally, in one article, 75% of the training sessions were unsupervised.[59] 237

Therefore, eight articles were included at this stage.[24, 34-37, 60-62] 238

A manual search within the reference lists of the included articles revealed five 239

additional potentially fitting articles. Two lacked the intervention group required[63, 64] and 240

two were non-randomized.[65, 66] One article met the inclusion criteria.[67] Four experts 241

revised the inclusion criteria and the list of articles and suggested eight articles based on their 242

titles and abstracts. Six were excluded: interventions were multicomponent;[68, 69] 243

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comparators performed no exercise;[70, 71] out of scope;[72] and unsupervised stretching 244

group.[73] Two articles were included,[74, 75] increasing the list to eleven articles,[24, 34-37, 245

60-62, 67, 74, 75] with 452 participants eligible for meta-analysis (Figure 1). 246

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Figure 1. Flowchart describing the study selection process. 251

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Records identified through database search

(n = 194)

Records after duplicates removed (n = 121)

Records screened (n = 121)

Records excluded (n = 106)

Full-text articles assessed for eligibility (n = 15)

Full-text articles excluded, with reasons (n = 7)

• 3 articles did not have the required intervention and/or comparators.

• 3 had at least one group of interest performing the intervention unsupervised.

• 1 had an undisclosed warm-up protocol that was longer than the intervention.

Studies included in qualitative synthesis (n = 8+1+2 = 11)

Studies included in quantitative synthesis (n = 11)

Additional records fitting inclusion criteria identified after search within the reference

lists of the included articles (n = 1)

Additional records fitting inclusion criteria recommended by four external experts from two countries and three different institutions

(n = 2)

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Study characteristics and results 255

The data items can be found in Table 1. The study of Wyon, Smith [62] required 256

consultation of a previous paper[76] to provide essential information. Samples ranged from 257

27[37] to 124 subjects,[34] including: trained participants,[24, 36, 61, 62] healthy sedentary 258

participants,[35, 60, 67] sedentary and trained participants,[75] workers with chronic neck 259

pain,[37] participants with fibromyalgia,[74] and elderly participants with difficulties in at least 260

one of four tasks: transferring, bathing, toileting, and walking.[34] Seven articles included only 261

women[36, 62, 67, 74] or predominantly women,[34, 35, 37] three investigated only men[24, 262

75] or predominantly men,[60] and one article had a balanced mixture of men and women.[61] 263

Interventions lasted between five[60] and 16 weeks[67]. Minimum weekly training frequency 264

was two sessions[37, 74] and maximum was five.[62] Six articles provided insufficient 265

information concerning session duration.[35, 36, 61, 62, 67, 75] Ten articles vaguely defined 266

training load for the ST and stretching groups,[24, 34, 37, 60, 61, 74, 75] or for stretching 267

groups.[35, 36, 67] Six articles did not report on using partial or full ROM during ST 268

exercises.[24, 34, 36, 37, 61, 67] Different stretching modalities were implemented: static 269

active,[35, 37, 60, 67, 74, 75] dynamic,[34, 36] dynamic with a 10-second hold,[24] static 270

active in one group and static passive in another,[62] and a combination of dynamic, static 271

active, and PNF.[61] 272

Hip joint ROM was assessed in seven articles,[24, 34, 36, 60-62, 67] knee ROM in 273

five,[34-36, 60, 75] shoulder ROM in four,[34, 36, 60, 74] elbow and trunk ROM in two,[34, 274

36] and cervical spine[37] and the ankle joint ROM in one article.[34] In one article, active 275

ROM (AROM) was tested for the trunk, while passive ROM (PROM) was tested for the other 276

joints.[34] In one article, PROM was tested for goniometric assessments and AROM for hip 277

flexion.[36] In another, AROM was assessed for the shoulder and PROM for the hip and 278

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knee.[60] Three articles only assessed PROM[35, 61, 75] and four AROM,[24, 37, 67, 74] 279

while one assessed both for the same joint.[62] 280

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Table 1. Characteristics of included randomized trials. 283 Article Population and common

program features Strength training group Comparator group(s)* ROM testing Qualitative

results for ROM Task-Specific

Resistance Training to Improve the Ability of

Activities of Daily Living–Impaired Older Adults to Rise from a Bed and

from a Chair.[34]

Subjects: 161. Health status: Elderly people

dependent on help for performing at least one of four

tasks: transferring, bathing, toileting and walking.

Gender: ST: 84% women; STRE: 88% women.

Age: ST: 82·0±6·4; STRE: 82·4±6·3.

Training status: Not participating in regular

strenuous exercise. Selection of subjects: Seven

congregate housing facilities. Length (weeks): 12. Weekly sessions: 3.

Adherence: average 81% of the sessions.

Funding: National Institute on Aging (NIA) Claude Pepper Older Adults Independence

Center (Grant AG0 8808 and NIA Grant AG10542), the Department of Veterans Affairs Rehabilitation

Research and Development, and the AARP-Andrus

Foundation. Conflicts of interest: N/A.

n = 81 (60 completed). Weekly volume (minutes):

180. Session duration in

minutes: 60. No. exercises per session:

16. No. sets and repetitions:

1*7-8 based on maximum target of 9 (bed-rise tasks). 1*5 based on maximum target of 6

(chair-rise tasks). Load: Unclear. Loads were incremented if

subjects were not feeling challenged enough.

Full or partial ROM: N/A.

Supervision ratio: 1:1.

STRE n = 80 (64 completed). Weekly volume (minutes): 180.

Session duration in minutes: 60. No. exercises per session: N/A. No. sets and repetitions: N/A. Stretching modality: Dynamic.

Load: Low-intensity, but without a specified criterion.

Full or partial ROM: N/A. Supervision ratio: One supervisor per group, but group size was N/A.

Joints and actions: Elbow (extension), shoulder

(abduction), hip (flexion and abduction), knee (flexion and

extension), ankle (dorsiflexion) and trunk

(flexion, extension, lateral flexion).

Positions: Supine (elbow, shoulder, hip, knee and

ankle); standing (lumbar spine).

Mode: Active for trunk, passive for the other joints.

Warm-up: N/A. Timing: Baseline, 6 weeks,

12 weeks. Results considered in the

tests: N/A. Data reliability: ICCs of 0·65

to 0·86 for trunk measures. Unreported for other

measures. No. testers: N/A.

Instructions during testing: N/A.

The ST group had significant

improvements in all ROM

measures, except hip flexion and

abduction.

The STRE group had no significant change in any of the ROM values.

Stretching versus strength training

in lengthened position in

subjects with tight hamstring

Subjects: 45 undergraduate students.

Health status: 30º knee extension deficit with the hip

at 90º when in supine position. No injuries in the

n = 15. Weekly volume (minutes):

N/A. Session duration in

minutes: N/A.

STRE n = 15. Weekly volume (minutes): N/A.

Session duration in minutes: N/A. No. exercises per session: 1.

No. sets and repetitions: 4*30’’. Stretching modality: Static.

Joints and actions: Knee (extension).

Positions: Sitting. Mode: Passive.

Warm-up: Yes, but unclear with regard to specifications.

None of the groups

experienced significant

improvements in ROM.

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muscles: A randomized controlled trial.[35]

lower limbs and no lower back pain.

Gender: 39 women, 6 men. Age: 21·33±1·76 years (ST); 22·60±1·84 years (STRE).

Training status: No participation in ST or STRE

programs in the previous year. Selection of subjects:

announcements posted at the University.

Length (weeks): 8. Weekly sessions: 3. Adherence: N/A. Funding: N/A.

Conflicts of interest: N/A.

No. exercises per session: 1.

No. sets and repetitions: 3*12.

Load: 60% of 1RM. Full or partial ROM:

Partial. Supervision ratio: N/A.

Load: Unclear. Full or partial ROM: Full.

Supervision ratio: N/A.

Timing: Baseline, 1-week post-protocol.

Results considered in the tests: mean of three

measures. Data reliability: High. No. testers: 1 (blinded).


Group-based exercise at

workplace: short-term effects of

neck and shoulder resistance

training in video display unit

workers with work-related chronic neck pain – a pilot randomized

trial.[37]

Subjects: 35 video display unit workers, 27 completed

the program. Health status: chronic neck

pain. Gender: 27 women, 8 men. Age: 43 (41-45) in ST; 42

(38·5-44) in STRE. Training status: N/A.

Selection of subjects: intranet form.

Length (weeks): 7. Weekly sessions: 2.

Adherence: average 85% of the sessions in ST and 86% in

STRE. Funding: Under

“disclosures”, the authors stated “none”.

Conflicts of interest: Under “disclosures”, the authors

stated “none”.





2-3*8-20. Isometric contractions up to 30’’.

Load: free-weights with a maximum of 75% MVC

and elastic bands of unspecified load.

Full or partial ROM: N/A.

Supervision ratio: ~1:8.

STRE n = 13. Weekly volume (minutes): 90.

Session duration in minutes: 45. No. exercises per session: 11.

No. sets and repetitions: 10*10’’. Stretching modality: Static.

Load: N/A. Full or partial ROM: N/A.

Supervision ratio: ~1:8.

Joints and actions: Cervical spine (flexion, extension, lateral flexion, rotation).

Positions: Sitting (flexion, extension, lateral flexion) and

supine position (rotation). Mode: Active.

Warm-up: N/A. Timing: Baseline, 1-week

post-protocol. Results considered in the

tests: N/A. Data reliability: N/A.

No. testers: 1 (blinded). Instructions during testing:

N/A.

Significant improvements in both groups for

all ROM measurements.

No differences

between the two groups.

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A randomized controlled trial of

muscle strengthening

versus flexibility training in

fibromyalgia.[74]

Subjects: 68; 56 completed the program.

Health status: Diagnosed with fibromyalgia (FM). Gender: Women.

Age: 49·2±6·36 years in ST, 46·4±8·56 in STRE.

Training status: 87% were sedentary. Not engaged in regular strength training

programs. Selection of subjects: FM

patients referred to rheumatology practice at a

teaching university. Length (weeks): 12. Weekly sessions: 2.

Adherence: 85% of the initial participants attended ≥13 of 24 classes. N/A for the 46 women that completed the

interventions. Funding: Individual National

Research Service Award (#1F31NR07337-01A1) from

the National Institutes of Health, a doctoral dissertation

grant (#2324938) from the Arthritis Foundation, and funds from the Oregon

Fibromyalgia Foundation. Conflicts of interest: N/A.




Presumably 12. No. sets and repetitions:

1*4-5, progressing to 1*12.

Load: Low intensity. Slower concentric

contractions with a 4’’ isometric hold in the end,

and a faster eccentric contraction.

Full or partial ROM: Full.

Supervision ratio: Presumably 1:28.


Session duration in minutes: 60. No. exercises per session:

Presumably 12. No. sets and repetitions: N/A.

Stretching modality: Static. Load: Low intensity.

Full or partial ROM: N/A. Supervision ratio: Presumably

1:28.

Joints and actions: Shoulder (the authors report on internal and external rotation, but the

movements used actually required a combination of

motions). Positions: Presumably

standing. Mode: Active.

Warm-up: N/A. Timing: Baseline, 12 weeks.

Results considered in the tests: N/A.

Data reliability: referral to a previous study, but no values

for these data. No. testers: 1.

Instructions during testing: Reach as far as possible.

Both groups had significant


No differences between groups.

Influence of Strength and Flexibility Training,

Combined or Isolated, on Strength and

Subjects:28 women. Health status: Presumably

healthy. Gender: Women.

Age: 46±6·5. Training status: Trained in

strength and stretching.



minutes: N/A. No. exercises per session:

8.


Session duration in minutes: 60. No. exercises per session: N/A. No. sets and repetitions: 3*30. Stretching modality: Dynamic.

Load: Stretch to mild discomfort.

Joints and actions: Shoulder (flexion, extension, abduction

and horizontal adduction) elbow (flexion), hip (flexion

and extension), knee (flexion), and trunk (flexion

and extension).

None of the groups

experienced significant


19

Flexibility Gains.[36]

Selection of subjects: Volunteers that would refrain

from exercise outside the intervention.

Length (weeks):12. Weekly sessions: 4. Not

explicit; 48 sessions over 12 weeks.

Adherence: Minimum was 44 of the 48 sessions.

Funding: N/A. Conflicts of interest: N/A.

No. sets and repetitions: 3*8-12 during the 1st

month; 3*6-10RM in the 2nd month; 3*10-15RM in

the 3rd month. Load: 6-15RM,

depending on the month. Full or partial ROM:

N/A. Supervision ratio: N/A.

Full or partial ROM: Full. Supervision ratio: N/A.

STRE + ST n = 7.

Completion of both protocols. Unknown duration.

ST + STRE n = 7.

Completion of both protocols in reverse order. Unknown duration.

Positions: Supine (shoulder flexion, abduction, horizontal

adduction, elbow and hip flexion), prone (shoulder and

hip extension, and knee flexion) and upright (trunk flexion and extension) for goniometric evaluations. Sitting for sit-and-reach.

Mode: Passive for goniometry. Active for sit-

and-reach. Warm-up: 5- minute walking

on treadmill at mild to moderate intensity and four

stretching exercises. Timing: Baseline, 12 weeks.

Results considered in the tests: Best of 3 trials.

Data reliability: Very high. No. testers: 1.


Effects of Flexibility and

Strength Interventions on Optimal Lengths

of Hamstring Muscle-Tendon

Units.[61]

Subjects: 40 college students. Health status: No history of

lower extremity injury in the 2 years prior to the study.

Gender: 20 men, 20 women.

Age: 18–24 years. Training status: participating

in exercise 2–3 times per week.

Selection of subjects: college students.

Length (weeks): 8. Weekly sessions: 3. Adherence: N/A.



minutes: N/A No. exercises per session:


2-4*8-15. For one exercise, 2*50-60’’.

Load: N/A. Full or partial ROM:




No. sets and repetitions: 2*15 for dynamic stretching, 2*40-60’’ for static stretching, 3*50’’ for PNF

and 3*40-50’’ for foam roll. Stretching modality: active static,

dynamic and PNF. Load: N/A.

Full or partial ROM: N/A. Supervision ratio: N/A.

Joints and actions: Hip (flexion).

Positions: Supine. Mode: Passive.

Warm-up: Six-minute warm-up including jogging and

jumping. Timing: Baseline, 8 weeks. Results considered in the tests: Mean of three trials.

Data reliability: Very high. No. testers: N/A.


Men and women in both groups significantly

improved ROM.

No differences between groups.

20

Funding: Partially supported by the National Natural

Science Foundation of China (Grant No.: 81572212) and the Fundamental Research

Fund for the Central Universities, Beijing Sport

University (Grant No.: 2017XS017).

Conflicts of interest: N/A. Resistance

training vs. static stretching: Effects on

flexibility and strength.[60]

Subjects: 37 college students. Health status: Healthy.

Gender: 30 men, 12 women; ratio is unclear in the final

sample. Age: 21·91±3·64 years.

Training status: Untrained. Selection of subjects:

Recruited from Physical Education or Exercise Science

Classes. Length (weeks): 5. Weekly sessions: 3. Adherence: N/A. Funding: N/A.



135-180. Session duration in

minutes: 45-60. No. exercises per session: eight in days 1 and 2, four

in day 3. No. sets and repetitions: 4

sets of unspecified repetitions. Load: N/A.

Full or partial ROM: Full.


STRE n = 12. Weekly volume (minutes): 75-90. Session duration in minutes: 25-

35. No. exercises per session: 13.

No. sets and repetitions: 1*30’’ for most stretches. 3*30’’ for one exercise and 3*20’’ for two. Stretching modality: Static.

Load: N/A. Full or partial ROM: Full.


Joints and actions: Hip (flexion, extension), knee (extension) and shoulder

(extension). Positions: Supine (knee and

hip). Prone (shoulder). Mode: Passive for hip and knee, active for shoulder. Warm-up: 5 minutes of stationary bicycle with

minimal resistance. Timing: Baseline, 1-week

post-protocol. Results considered in the


No. testers: 1. Instructions during testing:

Technical instructions specific to each test.

Both groups had significant

improvements in knee extension, hip flexion and

hip extension, but not shoulder extension.

No differences

between the interventions.

Eccentric training and

static stretching improve

hamstring flexibility of high school men.[75]

Subjects: 69 high-schoolers. Health status: Healthy, but

with a 30º loss of knee extension.

Gender: Men. Age: 16·45±0·96 years. Training status: Some

sedentary, others involved in exercise programs.

n= 24. Weekly volume (minutes):



1. No. sets and repetitions: 6

repetitions with 5’’

STRE n= 21. Weekly volume (minutes): N/A.


No. sets and repetitions: Unknown number of repetitions, each lasting

30’’. Stretching modality: Static.

Joints and actions: Knee (extension).

Positions: Supine. Mode: Passive.

Warm-up: No warm-up. Timing: Baseline, 6 weeks. Results considered in the tests: Two measures for

previous reliability

Both groups improved ROM.

No differences


21

Selection of subjects: Volunteers with tight

hamstrings. Length (weeks): 6.

Weekly sessions: 3 for STRE. N/A for ST.

Adherence: N/A for ST. STRE: subjects missing >4

sessions were excluded. Funding: N/A.


isometric hold between each.

Load: N/A. Full or partial ROM:

Full. Supervision ratio:

Description suggests a 1:1 ratio.

Load: Stretch until a gentle stretch was felt on the posterior thigh.

Full or partial ROM: Full. Supervision ratio: Description

suggests a 1:1 ratio.

calculations, but unclear for the groups’ evaluation.

Data reliability: Very high. No. testers: 2 (1 blinded).


Effects of flexibility

combined with plyometric

exercises vs. isolated

plyometric or flexibility mode

in adolescent men

hurdlers.[24]

Subjects: 34 trained hurdlers. Health status: No lower extremity injury in the

previous 30 days. Gender: Men.

Age: 15±0·7 years. Training status: ≥3 years of experience in hurdle racing.

Selection of subjects: Recruited from three athletic

teams. Length (weeks): 12. Weekly sessions: 4. Adherence: N/A.

Funding: No funding. Conflicts of interest: No

conflicts of interest.

n= 9. Weekly volume (minutes):




3*30’’. Load: Evolved from low to hard intensity, but no criteria were provided. Full or partial ROM:



Session duration in minutes: 80. No. exercises per session: 7.

No. sets and repetitions: 5*10’’. Stretching modality: Dynamic with

10’’ static hold. Load: Evolved from low to hard

intensity, but no criteria were provided.


STRE+ ST n = 9.

Weekly volume (minutes): 320. Session duration in minutes: 80. No. exercises per session: 11 (4

plyometric; 7 flexibility). No. sets and repetitions: 3*30’’ for plyometrics, 5*10’’ for stretching. Stretching modality: Dynamic with

10’’ static hold. Load: Evolved from low to hard

intensity, but no criteria were provided.


Joints and actions: Hip (flexion and extension).

Positions: Supine. Mode: Active.

Warm-up: N/A. Timing: Baseline, 12 weeks.

Results considered in the tests: Best of 3 attempts.

Data reliability: Referral to a previous study, but no values

for these data. No. testers: 2.


All interventions had significant


No differences


22

The influence of strength,

flexibility, and simultaneous training on

flexibility and strength

gains.[67]

Subjects: 80 women. Health status: Healthy.

Gender: Women. Age: 35±2·0 (ST), 34±1·2

(STRE), 35±1·8 (ST + STRE), 34±2·1 (non-

exercise). Training status: Sedentary.

Selection of subjects: Volunteers that were

sedentary ≥12 months. Length (weeks): 16. Weekly sessions: 3.

Adherence: Minimum was 46 of the 48 sessions.

Funding: N/A. Conflicts of interest: N/A.




8. No. sets and repetitions: 3*8-12 in the 1st and 4th months; 3*6-10 in 2nd month; 3*10-15 in 3rd

month. Load: 8-12RM (1st and

4th months); 6-10RM (2nd month); 10-15RM (3rd

month). Full or partial ROM:



Session duration in minutes: N/A. No. exercises per session: N/A. No. sets and repetitions: 4*15-

60’’. Duration of each set started at 15’’ and progressed to 60’’ during

the intervention. Stretching modality: Static.

Load: Performed at the point of mild discomfort.


ST + STRE n = 20.

STRE protocol followed by the ST protocol.

Joints and actions: Hip (flexion) and knee

(extension) combined. Positions: Sitting.

Mode: Active. Warm-up: 4 stretching

exercises (2*10’’). Timing: Baseline, 16 weeks.

Results considered in the tests: Maximum of 3

attempts. Data reliability: Very high.

No. testers: 1. Instructions during testing:

N/A.

The interventions significantly

improved ROM.

No differences between the

interventions.

A comparison of strength and

stretch interventions on

active and passive ranges of

movement in dancers: a

randomized control trial.[62]

Subjects: 39 dance students, 35 completed.

Health status: N/A. Gender: Women (39).

Age: 17±0·49 years (ST group); 17±0·56 years (low-intensity STRE); 17±0·56 years (moderate to high

intensity STRE). Training status: Moderately

trained dance students. Selection of subjects:

Recruited from dance college. Length (weeks): 6. Weekly sessions: 5. Adherence: N/A. Funding: N/A.





1. No. sets and repetitions: 3*5, increasing to 3*10

during the program. Each repetition included a 3’’

isometric hold. Load: Unclear, but using

body weight. Full or partial ROM:

Partial (final 10º). Supervision ratio: N/A.

Low-intensity STRE n = 13. Weekly volume (minutes): N/A.


No. sets and repetitions: N/A, but 1’ for each stretch.

Stretching modality: Active static. Load: 3/10 perceived exertion.


Moderate-intensity or high-

intensity STRE n = 11. Weekly volume (minutes): N/A.


No. sets and repetitions: N/A. Stretching modality: Passive.

Load: 8/10 perceived exertion. Full or partial ROM: N/A.

Joints and actions: Hip (flexion).

Positions: Standing. Mode: Active and passive. Warm-up: 10 minutes of

cardiovascular exercise and lower limb stretches.

Timing: Baseline, 6 weeks. Results considered in the


No. testers: N/A. Instructions during testing:

Positioning cues for ensuring proper posture.

The three groups significantly

improved passive ROM, without

differences between the

groups.

The moderate-to-high intensity

STRE group did not improve in

active ROM. The two other

interventions did.

23

Supervision ratio: N/A. Legend: N/A – Information not available. ST – Strength training. STRE - Stretching. ROM – Range of motion. MVC – Maximum voluntary contraction. PNF – 284 Proprioceptive neuromuscular facilitation. * Non-exercise groups are not considered in this column. 285 286

287

24

288

289

In seven articles,[24, 37, 60, 61, 67, 74] ST and stretching groups significantly 290

improved ROM, and the differences between the groups were non-significant. In one article, 291

the ST group had significant improvements in 8 of 10 ROM measures, while dynamic 292

stretching did not lead to improvement in any of the groups.[34] In another article, the three 293

groups significantly improved PROM, without between-group differences; the ST and the 294

static active stretching groups also significantly improved AROM.[62] In two articles, none of 295

the groups improved ROM.[35, 36] 296

297

Risk of bias within studies 298

Table 2 presents assessments of RoB. Bias arising from the randomization process was 299

low in four articles,[34, 36, 62, 74] moderate in one,[37] and high in six.[24, 35, 60, 61, 67, 300

75] Bias due to deviations from intended interventions, missing outcome data, and selection of 301

the reported results was low. Bias in measurement of the outcome was low in six articles,[35-302

37, 67, 74, 75] but high in five.[24, 34, 60-62] 303

304

305

25

306

Table 2. Assessments of risk of bias. 307

Cochrane’s RoB 2

Alexander, Galecki

[34]

Aquino, Fonseca

[35]

Caputo, Di Bari

[37]

Jones, Burckhard

t [74]

Leite, De Souza

Teixeira [36]

Li, Garrett [61]

Morton, Whitehead

[60]

Nelson and Bandy [75]

Racil, Jlid [24]

Simão, Lemos [67]

Wyon, Smith [62]

1.Bias arising from the randomization process 1.1.Was the allocation sequence random?

Yes. No

information.

Yes. Yes. No

information.

No information

.

No information

.

No information.

No information

.

No information

. Yes.

1.2.Was the allocation sequence concealed

until participants

were enrolled and assigned

to interventions

?

Yes. Probably no. Yes. Yes. Yes. Probably

no. Probably

no. Probably

no. Probably

no. Probably

no. Yes.

1.3.Did baseline

differences between groups

suggest a problem with

the randomizatio

n process?

No. No

information.

Yes. No. No. No. Probably no. No. No. No. No.

1.4.RoB judgement Low risk. High risk.

Some concerns

. Low risk. Low risk. High risk. High risk. High risk. High risk. High risk. Low

risk.

2.Bias due to deviations from intended interventions

26

(effect of assignment to intervention) 2.1.Were

participants aware of their

assigned intervention during the

trial?

Yes. Yes. Yes. Yes. Yes. Yes. Yes. Yes. Yes. Yes. Yes.

2.2.Were carers and

people delivering the interventions

aware of participants’

assigned intervention during the

trial?


2.3.If Y/PY/NI to 2.1 or 2.2: Were there deviations from the intended

intervention because of

the trial context?

Probably no.

Probably no.

Probably no.

Probably no.

Probably no.

Probably no.

Probably no.

Probably no.

Probably no.

Probably no.

Probably no.

2.4.If Y/PY to 2.3: Were

these deviations

likely to have affected the outcome?

N/A. N/A. N/A. N/A. N/A. N/A. N/A. N/A. N/A. N/A. N/A.

27

2.5.If Y/PY/NI to 2.4: Were

these deviations from the intended

intervention balanced between groups?


2.6.Was an appropriate

analysis used to estimate the effect of

assignment to intervention?

Probably yes.

Probably yes.

Probably yes.

Probably yes.

Probably yes.

Probably yes.

Probably yes.

Probably yes.

Probably yes.

Probably yes.

Probably yes.

2.7.If N/PN/NI to

2.6: Was there

potential for a substantial impact (on

the result) of the failure to

analyze participants in the group

to which they were

randomized)?


2.8.RoB judgement Low risk. Low risk. Low risk. Low risk. Low risk. Low risk. Low risk. Low risk. Low risk. Low risk. Low

risk. 3.Bias due to missing outcome data

3.1.Were data for this Yes. Yes. Yes. Yes. Yes. Yes. Yes. Yes. Yes. Yes. Yes.

28

outcome available for all, or nearly

all, participants randomized?

3.2.If N/PN/NI to 3.1.: Is there evidence that the result was not biased by

missing outcome

data?


3.3.If N/PN to 3.2: Could missingness

in the outcome

depend on its true value?


3.4.If Y/PY/NI to

3.3: Is it likely that

missingness in the

outcome depended on

its true value?


3.5.RoB judgement Low risk. Low risk. Low risk. Low risk. Low risk. Low risk. Low risk. Low risk. Low risk. Low risk. Low

risk. 4. Bias in measurement of the outcome

4.1.Was the method of

measuring the outcome

No. No. No. No. No. No. No. No. No. No. No.

29

inappropriate?

4.2.Could measurement

or ascertainment

of the outcome have

differed between

intervention groups?

Probably no.

Probably no.

Probably no.

Probably no.

Probably no.

Probably no.

Probably no.

Probably no.

Probably no.

Probably no.

Probably no.

4.3.If N/PN/NI to 4.1. and 4.2:

Were outcome assessors

aware of the intervention received by

study participants?

Probably yes. No. No. No. No. Probably

yes. Probably

yes. Probably

yes. Probably

yes. No. Probably yes.

4.4.If Y/PY/NI to 4.3: Could

assessment of the outcome have been

influenced by knowledge of intervention received?

Probably yes. N/A. N/A. N/A. N/A. Probably

yes. Probably

yes.

Probably no [blinded

goniometer].

Probably yes. N/A. Probabl

y yes.

4.5.If Y/PY/NI to

4.4: Is it likely that

assessment of

Probably yes. N/A. N/A. N/A. N/A. Probably

yes. Probably

yes. N/A. Probably yes. N/A. Probabl

y yes.

30

the outcome was

influenced by knowledge of intervention received? 4.6.RoB

judgement High risk. Low risk. Low risk. Low risk. Low risk. High risk. High risk. Low risk. High risk. Low risk. High risk.

5.Bias in selection of the reported results 5.1.Were the

data that produced this

result analyzed in accordance with a pre-specified

analysis plan that was finalized before

unblinded outcome data

were available for

analysis?


5.2.Is the numerical

result being assessed

likely to have been selected, on the basis

of the results, from multiple

eligible outcome

measurement

Probably no.

Probably no.

Probably no.

Probably no.

Probably no.

Probably no.

Probably no.

Probably no.

Probably no.

Probably no.

Probably no.

31

s (e.g., scales, definitions, time points) within the outcome domain? 5.3.Is the numerical

result being assessed

likely to have been selected, on the basis

of the results, from multiple

eligible analyses of the data?

Probably no.

Probably no.

Probably no.

Probably no.

Probably no.

Probably no.

Probably no.

Probably no.

Probably no.

Probably no.

Probably no.

RoB judgement Low risk. Low risk. Low risk. Low risk. Low risk. Low risk. Low risk. Low risk. Low risk. Low risk. Low

risk. 308

309

32

310

311

Synthesis of results 312

Comparisons were performed between ST and stretching groups, involving eleven 313

articles and 452 participants. Global effects on ROM were achieved pooling data from the 314

different joints. One article did not have the data required,[35] but the authors kindly supplied 315

it upon request. For another article,[36] we also requested data relative to the goniometric 316

evaluations, but obtained no response. Therefore, only data from the sit-and-reach test was 317

used. For one article,[37] means and SDs were obtained from 95% CIs, while in another SDs 318

were extracted from SEMs,[74] using Cochrane’s RevMan Calculator. 319

Of the five articles including both genders, four provided pooled data, with no 320

distinction between genders.[34, 35, 37, 60] One article presented data separated by gender, 321

without significant differences between men and women in response to interventions.[61] 322

Weighted formulas were applied sequentially for combining means and SDs of groups within 323

the same study.[38] Two studies presented the results separated by left and right lower limbs, 324

with both showing similar responses to the interventions;[24, 62] outcomes were combined 325

using the same weighted formulas for the means and SDs. Five articles only presented one 326

decimal place,[24, 34, 37, 61, 67] and so all values were rounded for uniformity. 327

Effects of ST versus stretching on ROM: no significant difference was noted between 328

ST and stretching (ES = -0×22; 95% CI = -0×55 to 0×12; p = 0×206; I2 = 65×4%; Egger’s test p = 329

0×563; Figure 2). The relative weight of each study in the analysis ranged from 6×4% to 12×7% 330

(the size of the plotted squares in Figure 2 reflects the statistical weight of each study). 331

332

333

33

334

335

Figure 2. Forest plot of changes in ROM after participating in stretching-based compared to strength-based 336

training interventions. Values shown are effect sizes (Hedges’s g) with 95% confidence intervals (CI). The size 337

of the plotted squares reflects the statistical weight of the study. 338

339

Additional analysis 340

Effects of ST versus stretching on ROM, moderated by study RoB in randomization: No 341

significant sub-group differences in ROM changes (p = 0·256) was found when programs with 342

high RoB (6 studies; ES = -0·41; 95% CI = -1·02 to 0·20; within-group I2 = 77·5%) were 343

compared to programs with low RoB (4 studies; ES = -0·03; 95% CI = -0·29 to 0·23; within-344

group I2 = 0·0%) (Supplementary figure 1). 345

Effects of ST versus stretching on ROM, moderated by study RoB in measurement of 346

the outcome: No significant sub-group difference in ROM changes (p = 0·320) was found 347

when programs with high RoB (5 studies; ES = -0·04; 95% CI = -0·31 to 0·24; within-group 348

I2 = 8·0%) were compared to programs with low RoB (6 studies; ES = -0·37; 95% CI = -0·95 349

to 0·22; within-group I2 = 77·3%) (Supplementary figure 2). 350

Effects of ST versus stretching on ROM, moderated by ROM type (active vs. passive): 351

No significant sub-group difference in ROM changes (p = 0·642) was found after training 352

Study name Hedges's g and 95% CI

Hedges's g

Alexander et al. (2001) 0.045Aquino et al. (2010) 0.087Caputo et al. (2017) 0.220Jones et al. (2002) -0.282Leite et al. (2015) -0.229Li et al. (2020) -0.616Morton et al. (2011) 0.123Nelson & Bandy (2004) -0.101Racil et al. (2020) -0.000Simão et al. (2011) -1.922Wyon et al. (2013) 0.247

-0.215

-3.00 -1.50 0.00 1.50 3.00Favours stretching Favours strength

Stretching

(n) Strength

(n)

34

programs that assessed active (8 groups; ES = -0·15; 95% CI = -0·65 to 0·36; within-group I2 353

= 78·7%) compared to passive ROM (6 groups; ES = -0·01; 95% CI = -0·27 to 0·24; within-354

group I2 = 15·3%) (Supplementary figure 3). 355

Effects of ST versus stretching on hip flexion ROM: Seven studies provided data for hip 356

flexion ROM (pooled n = 294). There was no significant difference between ST and stretching 357

interventions (ES = -0·24; 95% CI = -0·82 to 0·34; p = 0·414; I2 = 80·5%; Egger’s test p = 358

0·626; Supplementary figure 4). The relative weight of each study in the analysis ranged from 359

12·0% to 17·4% (the size of the plotted squares in Figure 6 reflects the statistical weight of 360

each study). 361

Effects of ST versus stretching on hip flexion ROM, moderated by study RoB in 362

randomization: No significant sub-group difference in hip flexion ROM changes (p = 0·311) 363

was found when programs with high RoB in randomization (4 studies; ES = -0·46; 95% CI = 364

-1·51 to 0·58; within-group I2 = 86·9%) were compared to programs with low RoB in 365

randomization (3 studies; ES = 0·10; 95% CI = -0·20 to 0·40; within-group I2 = 0·0%) 366

(Supplementary figure 5). 367

Effects of ST versus stretching on hip flexion ROM, moderated by ROM type (active vs. 368

passive): No significant sub-group difference in hip flexion ROM changes (p = 0·466) was 369

found after the programs assessed active (4 groups; ES = -0·38; 95% CI = -1·53 to 0·76; within-370

group I2 = 87·1%) compared to passive ROM (4 groups; ES = 0·08; 95% CI = -0·37 to 0·52; 371

within-group I2 = 56·5%) (Supplementary figure 6). 372

Effects of ST versus stretching on knee extension ROM: Four studies provided data for 373

knee extension ROM (pooled n = 223). There was no significant difference between ST and 374

stretching interventions (ES = 0·25; 95% CI = -0·02 to 0·51; p = 0·066; I2 = 0·0%; Egger’s test 375

p = 0·021; Supplementary figure 7). After the application of the trim and fill method, the 376

adjusted values changed to ES = 0·33 (95% CI = 0·10 to 0·57), favoring ST. The relative 377

35

weight of each study in the analysis ranged from 11·3% to 54·2% (the size of the plotted 378

squares in Supplementary figure 7 reflects the statistical weight of each study). 379

One article behaved as an outlier in all comparisons (favoring stretching),[67] but after 380

sensitivity analysis the results remained unchanged (p>0·05), with all ST vs. stretching 381

comparisons remaining non-significant. 382

383

Confidence in cumulative evidence 384

Table 3 presents GRADE assessments. ROM is a continuous variable, and so a high 385

degree of heterogeneity was expected.[77] Imprecision was moderate, likely reflecting the fact 386

that ROM is a continuous variable. Overall, both ST and stretching consistently promoted 387

ROM gains, but no recommendation could be made favoring one protocol. 388

389

390

36

391

Table 3. GRADE assessment for the certainty of evidence. 392 Outcome Study

design RoB1 Publication

bias Inconsistency Indirectness Imprecision Quality

of evidence

Recommendation

ROM 11 RCTs, 452 participants in meta-analysis.

Randomization – low in four articles, moderate in one, and high in six.

No publication bias.

9 RCTs showed improvements in ROM in both groups. 2 RCTs showed no changes in ROM in either group. 11 RCTs showed effects of equal magnitude for ST and stretching.2

No serious indirectness.

Moderate.3 Moderate. ⨁⨁⨁

Strong recommendation for either strength training or stretching4. No recommendation for choosing one of the protocols over the other, as their efficacy in ROM gains was statistically not different.

Deviations from intended interventions – Low. Missing outcome data – Low. Measurement of the outcome – low in six articles and high in five. Selection of the reported results – Low.

1 - Meta-analyses moderated by RoB showed no differences between studies with low and high risk. 2 - Because ROM is a continuous variable, high heterogeneity was expected. However, this heterogeneity is mostly between small and large beneficial effects. No adverse effects were reported. 3 - Expected because ROM is a continuous variable. Furthermore, imprecision referred to small to large beneficial effects. 4 – Both strength training and stretching presented benefits without reported adverse effects.

Legend: ROM – Range of motion. RCTs: randomized controlled trials. RoB: risk of bias. 393 394

395

37

396

DISCUSSION 397

Summary of evidence 398

The aim of this SRMA was to compare the effects of supervised and randomized ST 399

compared to stretching protocols on ROM, in participants of any health and training status. 400

Qualitative synthesis showed that ST and stretching interventions were not statistically 401

different in improving ROM, regardless of the nature of the interventions and moderator 402

variables such as gender, health, or training status. Meta-analysis including 11 articles and 452 403

participants showed that ST and stretching interventions were not statistically different in 404

active and passive ROM changes, regardless of RoB in the randomization process, or in 405

measurement of the outcome. RoB was low for deviations from intended interventions, missing 406

outcome data, and selection of the reported results. No publication bias was detected. 407

High heterogeneity is expected in continuous variables,[77] such as ROM. However, 408

more research should be conducted to afford sub-group analysis according to characteristics of 409

the analyzed population, as well as protocol features. For example, insufficient reporting of 410

training volume and intensity meant it was impossible to establish effective dose-response 411

relationships, although a minimum of 5 weeks of intervention,[60] and two weekly sessions 412

were sufficient to improve ROM.[37, 74] Studies were not always clear with regard to the 413

intensity used in ST and stretching protocols. Assessment of stretching intensity is complex, 414

but a practical solution may be to apply scales of perceived exertion,[62] or the Stretching 415

Intensity Scale.[78] ST intensity may also moderate effects on ROM,[79] and ST with full vs 416

partial ROM may have distinct neuromuscular effects[70] and changes in fascicle length.[28] 417

Again, information was insufficient to discuss these factors, which could potentially explain 418

part of the heterogeneity of results. 419

38

Most studies showed ROM gains in ST and stretching interventions, although in two 420

studies neither group showed improvements.[35, 36] Though adherence rates were unreported 421

by Aquino, Fonseca [35], they were above 91.7% in Leite, De Souza Teixeira [36], thus 422

providing an unlikely explanation for these results. In the study of Aquino, Fonseca [35], the 423

participants increased their stretch tolerance, and the ST group changed the peak torque angle, 424

despite no ROM gains. The authors acknowledged that there was high variability in 425

measurement conditions (e.g., room temperature), which could have interfered with 426

calculations. Leite, De Souza Teixeira [36] suggested that the use of dynamic instead of static 427

stretching could explain the lack of ROM gains in the stretching and stretching + ST groups. 428

However, other studies using dynamic stretching have shown ROM gains.[24, 34] 429

Furthermore, Leite, De Souza Teixeira [36] provided no interpretation for the lack of ROM 430

gains in the ST group. 431

Globally, however, both ST and stretching were effective to improve ROM. Why would 432

ST improve ROM in a manner that is not statistically distinguishable from stretching? ST with 433

an eccentric focus demands the muscles to produce force on elongated positions, and a meta-434

analysis showed limited to moderate evidence that eccentric ST is associated with increases in 435

fascicle length.[80] Likewise, a recent study showed that 12 sessions of eccentric ST increased 436

fascicle length of the biceps femoris long head.[29] However, ST with an emphasis in 437

concentric training has been shown to increase fascicle length when full ROM was 438

required.[28] In a study with nine older adults, ST increased fascicle length in both the eccentric 439

and concentric groups, albeit more prominently in the former.[81] Conversely, changes in 440

pennation angle were superior in the concentric group (35% increase versus 5% increase). 441

Plyometric training can also increase plantar flexor tendon extensibility.[33] 442

One article showed significant reductions in pain associated with increases in 443

strength.[37] Thus, decreased pain sensitivity may be another mechanism through which ST 444

39

promotes ROM gains. An improved agonist-antagonist coactivation is another possible 445

mechanism promoting ROM gains, through better adjusted force ratios.[31, 62] Also, some 446

articles included in the meta-analysis assessed other outcomes in addition to ROM, and these 447

indicated that ST programs may have additional advantages when compared to stretching, such 448

as greater improvements in neck flexors endurance,[37] ten repetition maximum Bench Press 449

and Leg Press,[36, 67] and countermovement jump and 60-m sprint with hurdles,[24] which 450

may favor the choice of ST over stretching interventions. 451

452

453

Limitations 454

After protocol registration, we chose to improve upon the design, namely adding two 455

dimensions (directness and imprecision) that would provide a complete GRADE assessment. 456

Furthermore, subgroup analyses were not planned a priori. There is a risk of multiple subgroup 457

analyses generating a false statistical difference, merely to the number of analyses 458

conducted.[38] However, all analyses showed an absence of significant differences and 459

therefore provide a more complete understanding that the effects of ST or stretching on ROM 460

are consistent across conditions. Looking backwards, perhaps removing the filters used in the 461

initial searches could have provided a greater number of records. Notwithstanding, it would 462

also likely provide a huge number of non-relevant records, including opinion papers and 463

reviews. Moreover, consultation with four independent experts may hopefully have resolved 464

this shortcoming. 465

Due to the heterogeneity of populations analysed, sub-group analysis according to sex 466

or age group were not possible, and so it would be important to explore if these features interact 467

with the protocols in meaningful ways. And there was a predominance of studies with women, 468

meaning more research with men is advised. There was also a predominance of assessments of 469

40

hip joint ROM, followed by knee and shoulder, with the remaining joints receiving little to no 470

attention. In addition, dose-response relationships could not be addressed, mainly due to poor 471

reporting. 472

473

CONCLUSIONS 474

Overall, ST and stretching were not statistically different in ROM improvements, both 475

in short-term interventions[60] and in longer-term protocols,[67] suggesting that a combination 476

of neural and mechanical factors is at play. Therefore, if ROM gains are a desirable outcome, 477

both ST and stretching can be prescribed, in the absence of specific contraindications, 478

especially because studies did not report any adverse effects. People that do not respond well 479

or do not adhere to stretching protocols can change to ST programs, and vice-versa. 480

Furthermore, session duration may negatively impact adherence to an exercise program.[82] 481

Since ST generates ROM gains similar to those obtained with stretching, clinicians may 482

prescribe smaller, more time-effective programs when deemed convenient and appropriate, 483

thus eventually increasing patient adherence rates. 484

485

486

41

487

488

Declaration of interests: J.M. owns a company focused on Personal Trainer’s education but 489

made no attempt to bias the team in protocol design and search process and had no role in 490

extracting data for meta-analyses. The multiple cross-checks described in the methods 491

provided objectivity to data extraction and analysis. Additionally, J.M. had no financial 492

involvement in this manuscript. The other authors have no conflict of interest to declare. 493

494

Funding: No funding was used for conducting this meta-analysis. 495

496

497

42

498

Author’s contributions (following ICMJE recommendations) 499

Authors Substantial contributions to the conceptualization or design of the study; OR the

acquisition, analysis, or

interpretation of data

Drafting the manuscript; OR

revising the manuscript critically for important intellectual

content

Final approval

of the version to

be published

Agreement to be accountable for all

aspects of the work, and to ensure that issues

related to the accuracy or integrity of any part of

the work are appropriately

investigated and resolved José Afonso √ √ √ √

Rodrigo Ramirez-Campillo

√ √ √ √

João Moscão √ √ √ √ Tiago Rocha √ √ √ √

Rodrigo Zacca √ √ √ √ Alexandre Martins √ √ √ √ André A. Milheiro √ √ √ √

João Ferreira √ √ √ √ Hugo Sarmento √ √ √ √ Filipe Manuel

Clemente √ √ √ √

Acknowledgements Role Richard Inman Language editing and proof reading. Pedro Morouço Thorough pre-submission scientific review of the manuscript. Signed consent form

below. Daniel Moreira-

Gonçalves, Fábio Yuzo Nakamura plus

two experts who wished to remain

anonymous.

Review of inclusion criteria and included articles, and proposal of additional articles to be included in the systematic review and meta-analysis.

Signed consent forms below.

500

501

43

502

REFERENCES 503

1. ACSM. ACSM’s Guidelines for Exercise Testing and Prescription (10th Ed.): Wolters 504

Kluwer; 2018. 505

2. de Zoete RM, Armfield NR, McAuley JH, Chen K, Sterling M. Comparative 506

effectiveness of physical exercise interventions for chronic non-specific neck pain: a 507

systematic review with network meta-analysis of 40 randomised controlled trials. Br J Sports 508

Med. 2020 Nov 2. 509

3. Morris PE, Berry MJ, Files DC, Thompson JC, Hauser J, Flores L, et al. Standardized 510

Rehabilitation and Hospital Length of Stay Among Patients With Acute Respiratory Failure: 511

A Randomized Clinical Trial. Jama. 2016 Jun 28;315(24):2694-702. 512

4. Gross AM, Wolters PL, Dombi E, Baldwin A, Whitcomb P, Fisher MJ, et al. 513

Selumetinib in Children with Inoperable Plexiform Neurofibromas. N Engl J Med. 2020 Apr 514

9;382(15):1430-42. 515

5. Learmonth ID, Young C, Rorabeck C. The operation of the century: total hip 516

replacement. Lancet. 2007 Oct 27;370(9597):1508-19. 517

6. Pozzi F, Plummer HA, Shanley E, Thigpen CA, Bauer C, Wilson ML, et al. Preseason 518

shoulder range of motion screening and in-season risk of shoulder and elbow injuries in 519

overhead athletes: systematic review and meta-analysis. Br J Sports Med. 2020 520

Sep;54(17):1019-27. 521

7. Moreno-Pérez V, Del Coso J, Raya-González J, Nakamura FY, Castillo D. Effects of 522

basketball match-play on ankle dorsiflexion range of motion and vertical jump performance in 523

semi-professional players. J Sports Med Phys Fitness. 2020 Jan;60(1):110-8. 524

8. Downs J, Wasserberger K, Oliver GD. Influence of a Pre-throwing Protocol on Range 525

of Motion and Strength in Baseball Athletes. Int J Sports Med. 2020 Aug 26. 526

44

9. Li Y, Koldenhoven RM, Jiwan NC, Zhan J, Liu T. Trunk and shoulder kinematics of 527

rowing displayed by Olympic athletes. Sports Biomech. 2020 Jul 17:1-13. 528

10. Blazevich A, Cannavan D, Waugh CM, Miller SC, Thorlund JB, Aagaard P, et al. 529

Range of motion, neuromechanical, and architectural adaptations to plantar flexor stretch 530

training in humans. J Appl Physiol. 2014;117(5):452-62. 531

11. Guissard N, Duchateau J. Effect of static stretch training on neural and mechanical 532

properties of the human plantar-flexor muscles. Muscle Nerve. 2004 Feb;29(2):248-55. 533

12. Lima CD, Brown LE, Li Y, Herat N, Behm D. Periodized versus Non-periodized 534

Stretch Training on Gymnasts Flexibility and Performance. Int J Sports Med. 2019 535

Nov;40(12):779-88. 536

13. Behm DG, Kay AD, Trajano GS, Blazevich AJ. Mechanisms underlying performance 537

impairments following prolonged static stretching without a comprehensive warm-up. Eur J 538

Appl Physiol. 2020 Nov 11. 539

14. Deyo RA, Walsh NE, Martin DC, Schoenfeld LS, Ramamurthy S. A controlled trial of 540

transcutaneous electrical nerve stimulation (TENS) and exercise for chronic low back pain. N 541

Engl J Med. 1990 Jun 7;322(23):1627-34. 542

15. Lamb SE, Williamson EM, Heine PJ, Adams J, Dosanjh S, Dritsaki M, et al. Exercises 543

to improve function of the rheumatoid hand (SARAH): a randomised controlled trial. Lancet. 544

2015 Jan 31;385(9966):421-9. 545

16. Kokkonen J, Nelson AG, Eldredge C, Winchester JB. Chronic static stretching 546

improves exercise performance. Med Sci Sports Exerc. 2007;39(10):1825-31. 547

17. Santos C, Beltrão NB, Pirauá ALT, Durigan JLQ, Behm D, de Araújo RC. Static 548

Stretching Intensity Does Not Influence Acute Range of Motion, Passive Torque, and Muscle 549

Architecture. J Sport Rehabil. 2020;29(1):1-6. 550

45

18. Iwata M, Yamamoto A, Matsuo S, Hatano G, Miyazaki M, Fukaya T, et al. Dynamic 551

stretching has sustained effects on range of motion and passive stiffness of the hamstring 552

muscles. J Sports Sci Med. 2019;18(1):13-20. 553

19. Lempke L, Wilkinson R, Murray C, Stanek J. The Effectiveness of PNF Versus Static 554

Stretching on Increasing Hip-Flexion Range of Motion. J Sport Rehabil. 2018;27(3):289-94. 555

20. Ford GS, Mazzone MA, Taylor K. The effect of 4 different durations of static hamstring 556

stretching on passive knee-extension range of motion. Journal of Sports Rehabilitation. 557

2005;14(2):95-107. 558

21. Frasson VB, Vaz MA, Morales AB, Torresan A, Telöken MA, Gusmão PDF, et al. Hip 559

muscle weakness and reduced joint range of motion in patients with femoroacetabular 560

impingement syndrome: a case-control study. Braz J Phys Ther. 2020 Jan-Feb;24(1):39-45. 561

22. Pettersson H, Boström C, Bringby F, Walle-Hansen R, Jacobsson LTH, Svenungsson 562

E, et al. Muscle endurance, strength, and active range of motion in patients with different 563

subphenotypes in systemic sclerosis: a cross-sectional cohort study. Scand J Rheumatol. 2019 564

2019/03/04;48(2):141-8. 565

23. Takeda H, Nakagawa T, Nakamura K, Engebretsen L. Prevention and management of 566

knee osteoarthritis and knee cartilage injury in sports. Br J Sports Med. 2011 Apr;45(4):304-9. 567

24. Racil G, Jlid MC, Bouzid MS, Sioud R, Khalifa R, Amri M, et al. Effects of flexibility 568

combined with plyometric exercises vs. isolated plyometric or flexibility mode in adolescent 569

male hurdlers. J Sports Med Phys Fitness. 2020;60(1):45-52. 570

25. Saraiva AR, Reis VM, Costa PB, Bentes CM, Costae Silva GV, Novaes JS. Chronic 571

Effects of different resistance training exercise orders on flexibility in elite judo athletes. 572

Journal of Human Kinetics. 2014;40(1):129-37. 573

46

26. Carneiro NH, Ribeiro AS, Nascimento MA, Gobbo LA, Schoenfeld BJ, Achour A, et 574

al. Effects of different resistance training frequencies on flexibility in older women. Clin Interv 575

Aging. 2015;10:531-8. 576

27. Ylinen J, Takala EP, Nykänen M, Häkkinen A, Mälkiä E, Pohjolainen T, et al. Active 577

neck muscle training in the treatment of chronic neck pain in women: a randomized controlled 578

trial. Jama. 2003 May 21;289(19):2509-16. 579

28. Valamatos MJ, Tavares F, Santos RM, Veloso AP, Mil-Homens P. Influence of full 580

range of motion vs. equalized partial range of motion training on muscle architecture and 581

mechanical properties. Eur J Appl Physiol. 2018 Sep;118(9):1969-83. 582

29. Marušič J, Vatovec R, Marković G, Šarabon N. Effects of eccentric training at long-583

muscle length on architectural and functional characteristics of the hamstrings. Scand J Med 584

Sci Sports. 2020 Jul 24. 585

30. Bourne MN, Duhig SJ, Timmins RG, Williams MD, Opar DA, Al Najjar A, et al. 586

Impact of the Nordic hamstring and hip extension exercises on hamstring architecture and 587

morphology: implications for injury prevention. Br J Sports Med. 2017 Mar;51(5):469-77. 588

31. de Boer MD, Morse CI, Thom JM, de Haan A, Narici MV. Changes in antagonist 589

muscles' coactivation in response to strength training in older women. J Gerontol A Biol Sci 590

Med Sci. 2007 Sep;62(9):1022-7. 591

32. Silva-Batista C, Mattos EC, Corcos DM, Wilson JM, Heckman CJ, Kanegusuku H, et 592

al. Resistance training with instability is more effective than resistance training in improving 593

spinal inhibitory mechanisms in Parkinson's disease. J Appl Physiol (1985). 2017 Jan 594

1;122(1):1-10. 595

33. Kubo K, Ishigaki T, Ikebukuro T. Effects of plyometric and isometric training on 596

muscle and tendon stiffness in vivo. Physiol Rep. 2017 Aug;5(15). 597

47

34. Alexander NB, Galecki AT, Grenier ML, Nyquist LV, Hofmeyer MR, Grunawalt JC, 598

et al. Task-specific resistance training to improve the ability of activities of daily living-599

impaired older adults to rise from a bed and from a chair. J Am Geriatr Soc. 2001;49(11):1418-600

27. 601

35. Aquino CF, Fonseca ST, Goncalves GG, Silva PL, Ocarino JM, Mancini MC. 602

Stretching versus strength training in lengthened position in subjects with tight hamstring 603

muscles: a randomized controlled trial. Man Ther. 2010 Feb;15(1):26-31. 604

36. Leite T, De Souza Teixeira A, Saavedra F, Leite RD, Rhea MR, Simão R. Influence of 605

strength and flexibility training, combined or isolated, on strength and flexibility gains. J 606

Strength Cond Res. 2015;29(4):1083-8. 607

37. Caputo GM, Di Bari M, Naranjo Orellana J. Group-based exercise at workplace: short-608

term effects of neck and shoulder resistance training in video display unit workers with work-609

related chronic neck pain-a pilot randomized trial. Clin Rheumatol. 2017 Oct;36(10):2325-33. 610

38. Higgins JP, Thomas J, Chandler J, Cumpston M, Li T, Page MJ, et al. Cochrane 611

Handbook for Systematic Reviews of Interventions (2nd Ed.). Chichester (UK): John Wiley & 612

Sons; 2019. 613

39. Moher D, Liberati A, Tetzlaff J, Altman DG. Preferred reporting items for systematic 614

reviews and meta-analyses: the PRISMA statement. PLoS Med. 2009 Jul 21;6(7):e1000097. 615

40. Bleakley C, MacAuley D. The quality of research in sports journals. British Journal of 616

Sports Medicine. 2002;36(2):124. 617

41. Sterne JAC, Savović J, Page MJ, Elbers RG, Blencowe NS, Boutron I, et al. RoB 2: a 618

revised tool for assessing risk of bias in randomised trials. Bmj. 2019;366:l4898. 619

42. Skrede T, Steene-Johannessen J, Anderssen SA, Resaland GK, Ekelund U. The 620

prospective association between objectively measured sedentary time, moderate-to-vigorous 621

48

physical activity and cardiometabolic risk factors in youth: a systematic review and meta-622

analysis. Obes Rev. 2019 Jan;20(1):55-74. 623

43. Drahota A, Beller E. RevMan Calculator for Microsoft Excel [Computer software]: 624

Cochrane; 2020. 625

44. Deeks JJ, Higgins JP, Altman DG. Analysing data and undertaking meta-analyses. In: 626

Higgins JP, Green S, editors. Cochrane Handbook for Systematic Reviews of Interventions: 627

The Cochrane Collaboration The Cochrane Collaboration; 2008. p. 243-96. 628

45. Kontopantelis E, Springate DA, Reeves D. A re-analysis of the Cochrane Library data: 629

the dangers of unobserved heterogeneity in meta-analyses. PLoS One. 2013;8(7):e69930. 630

46. Hopkins WG, Marshall SW, Batterham AM, Hanin J. Progressive statistics for studies 631

in sports medicine and exercise science. Med Sci Sports Exerc. 2009 Jan;41(1):3-13. 632

47. Higgins JP, Thompson SG. Quantifying heterogeneity in a meta-analysis. Stat Med. 633

2002 Jun 15;21(11):1539-58. 634

48. Egger M, Davey Smith G, Schneider M, Minder C. Bias in meta-analysis detected by a 635

simple, graphical test. Bmj. 1997 Sep 13;315(7109):629-34. 636

49. Duval S, Tweedie R. Trim and fill: A simple funnel-plot-based method of testing and 637

adjusting for publication bias in meta-analysis. Biometrics. 2000 Jun;56(2):455-63. 638

50. Shi L, Lin L. The trim-and-fill method for publication bias: practical guidelines and 639

recommendations based on a large database of meta-analyses. Medicine (Baltimore). 2019 640

Jun;98(23):e15987. 641

51. Shea BJ, Reeves BC, Wells G, Thuku M, Hamel C, Moran J, et al. AMSTAR 2: a 642

critical appraisal tool for systematic reviews that include randomised or non-randomised 643

studies of healthcare interventions, or both. Bmj. 2017 Sep 21;358:j4008. 644

49

52. Guyatt GH, Oxman AD, Akl EA, Kunz R, Vist G, Brozek J, et al. GRADE guidelines: 645

1. Introduction-GRADE evidence profiles and summary of findings tables. J Clin Epidemiol. 646

2011 Apr;64(4):383-94. 647

53. Al-Wahab MGA, Salem EES, El-Hadidy EI, El-Barbary HM. Effect of plyometric 648

training on shoulder strength and active movements in children with Erb’s palsy. Int J 649

Pharmtech Res. 2016;9(4):25-33. 650

54. Fernandez-Fernandez J, Ellenbecker T, Sanz-Rivas D, Ulbricht A, Ferrauti A. Effects 651

of a 6-Week Junior Tennis Conditioning Program on Service Velocity. J Sports Sci Med. 2013 652

Jun;12(2):232-9. 653

55. de Resende-Neto AG, do Nascimento MA, de Sa CA, Ribeiro AS, Desantana JM, da 654

Silva-Grigoletto ME. Comparison between functional and traditional training exercises on joint 655

mobility, determinants of walking and muscle strength in older women. J Sports Med Phys 656

Fitness. 2019 Oct;59(10):1659-68. 657

56. Hajihosseini E, Norasteh A, Shamsi A, Daneshmandi H, Shahheidari S. Effects of 658

strengthening, stretching and comprehensive exercise program on the strength and range of 659

motion of the shoulder girdle muscles in upper crossed syndrome. Med Sport. 2016;69(1):24-660

40. 661

57. Fukuchi RK, Stefanyshyn DJ, Stirling L, Ferber R. Effects of strengthening and 662

stretching exercise programmes on kinematics and kinetics of running in older adults: A 663

randomised controlled trial. J Sports Sci. 2016;34(18):1774-81. 664

58. Häkkinen A, Kautiainen H, Hannonen P, Ylinen J. Strength training and stretching 665

versus stretching only in the treatment of patients with chronic neck pain: A randomized one-666

year follow-up study. Clin Rehabil. 2008;22(7):592-600. 667

59. Kalkman BM, Holmes G, Bar-On L, Maganaris CN, Barton GJ, Bass A, et al. 668

Resistance training combined with stretching increases tendon stiffness and is more effective 669

50

than stretching alone in children with cerebral palsy: A randomized controlled trial. Front 670

Pediatr. 2019;7:Article 333. 671

60. Morton SK, Whitehead JR, Brinkert RH, Caine DJ. Resistance training vs. static 672

stretching: Effects on flexibility and strength. J Strength Cond Res. 2011;25(12):3391-8. 673

61. Li S, Garrett WE, Best TM, Li H, Wan X, Liu H, et al. Effects of flexibility and strength 674

interventions on optimal lengths of hamstring muscle-tendon units. J Sci Med Sport. 675

2020;23(2):200-5. 676

62. Wyon MA, Smith A, Koutedakis Y. A comparison of strength and stretch interventions 677

on active and passive ranges of movement in dancers: A randomized controlled trial. J Strength 678

Cond Res. 2013;27(11):3053-9. 679

63. Girouard CK, Hurley BF. Does strength training inhibit gains in range of motion from 680

flexibility training in older adults? Med Sci Sports Exerc. 1995 Oct;27(10):1444-9. 681

64. Raab DM, Agre JC, McAdam M, Smith EL. Light resistance and stretching exercise in 682

elderly women: effect upon flexibility. Arch Phys Med Rehabil. 1988 Apr;69(4):268-72. 683

65. Klinge K, Magnusson SP, Simonsen EB, Aagaard P, Klausen K, Kjaer M. The effect 684

of strength and flexibility training on skeletal muscle electromyographic activity, stiffness, and 685

viscoelastic stress relaxation response. Am J Sports Med. 1997 Sep-Oct;25(5):710-6. 686

66. Nóbrega AC, Paula KC, Carvalho AC. Interaction between resistance training and 687

flexibility training in healthy young adults. J Strength Cond Res. 2005 Nov;19(4):842-6. 688

67. Simão R, Lemos A, Salles B, Leite T, Oliveira É, Rhea M, et al. The influence of 689

strength, flexibility, and simultaneous training on flexibility and strength gains. J Strength 690

Cond Res. 2011 May;25(5):1333-8. 691

68. Chen Y-H, Lin C-R, Liang W-A, Huang C-Y. Motor control integrated into muscle 692

strengthening exercises has more effects on scapular muscle activities and joint range of motion 693

51

before initiation of radiotherapy in oral cancer survivors with neck dissection: A randomized 694

controlled trial. PLoS ONE. 2020;15(8):e0237133-e. 695

69. Venkataraman K, Tai BC, Khoo EYH, Tavintharan S, Chandran K, Hwang SW, et al. 696

Short-term strength and balance training does not improve quality of life but improves 697

functional status in individuals with diabetic peripheral neuropathy: a randomised controlled 698

trial. Diabetologia. 2019 2019/12/01;62(12):2200-10. 699

70. Pallarés JG, Cava AM, Courel-Ibáñez J, González-Badillo JJ, Morán-Navarro R. Full 700

squat produces greater neuromuscular and functional adaptations and lower pain than partial 701

squats after prolonged resistance training. Eur J Sport Sci. 2020 Feb;20(1):115-24. 702

71. Çergel Y, Topuz O, Alkan H, Sarsan A, Sabir Akkoyunlu N. The effects of short-term 703

back extensor strength training in postmenopausal osteoporotic women with vertebral 704

fractures: comparison of supervised and home exercise program. Arch Osteoporos. 2019 Jul 705

27;14(1):82. 706

72. Albino ILR, Freitas CdlR, Teixeira AR, Gonçalves AK, Santos AMPVd, Bós ÂJG. 707

Influência do treinamento de força muscular e de flexibilidade articular sobre o equilíbrio 708

corporal em idosas. Rev Bras Geriatr Gerontol. 2012;15:17-25. 709

73. LeCheminant JD, Hinman T, Pratt KB, Earl N, Bailey BW, Thackeray R, et al. Effect 710

of resistance training on body composition, self-efficacy, depression, and activity in 711

postpartum women. Scand J Med Sci Sports. 2014 Apr;24(2):414-21. 712

74. Jones KD, Burckhardt CS, Clark SR, Bennett RM, Potempa KM. A randomized 713

controlled trial of muscle strengthening versus flexibility training in fibromyalgia. J 714

Rheumatol. 2002 May;29(5):1041-8. 715

75. Nelson RT, Bandy WD. Eccentric Training and Static Stretching Improve Hamstring 716

Flexibility of High School Males. J Athl Train. 2004;39(3):254-8. 717

52

76. Wyon MA, Felton L, Galloway S. A comparison of two stretching modalities on lower-718

limb range of motion measurements in recreational dancers. J Strength Cond Res. 2009 719

Oct;23(7):2144-8. 720

77. Guyatt GH, Oxman AD, Kunz R, Woodcock J, Brozek J, Helfand M, et al. GRADE 721

guidelines: 7. Rating the quality of evidence - inconsistency. J Clin Epidemiol. 2011 722

Dec;64(12):1294-302. 723

78. Freitas SR, Vaz JR, Gomes L, Silvestre R, Hilário E, Cordeiro N, et al. A New Tool to 724

Assess the Perception of Stretching Intensity. The Journal of Strength & Conditioning 725

Research. 2015;29(9). 726

79. Fatouros IG, Kambas A, Katrabasas I, Leontsini D, Chatzinikolaou A, Jamurtas AZ, et 727

al. Resistance training and detraining effects on flexibility performance in the elderly are 728

intensity-dependent. J Strength Cond Res. 2006;20(3):634-42. 729

80. Gérard R, Gojon L, Decleve P, Van Cant J. The Effects of Eccentric Training on Biceps 730

Femoris Architecture and Strength: A Systematic Review With Meta-Analysis. J Athl Train. 731

2020 May;55(5):501-14. 732

81. Reeves ND, Maganaris CN, Longo S, Narici MV. Differential adaptations to eccentric 733

versus conventional resistance training in older humans. Exp Physiol. 2009 Jul;94(7):825-33. 734

82. Medina-Mirapeix F, Escolar-Reina P, Gascón-Cánovas JJ, Montilla-Herrador J, 735

Jimeno-Serrano FJ, Collins SM. Predictive factors of adherence to frequency and duration 736

components in home exercise programs for neck and low back pain: an observational study. 737

BMC musculoskeletal disorders. 2009;10:Article 155. 738

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