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Self-selected or imposed exercise? A differentapproach for affective comparisonsBruno Ribeiro Ramalho Oliveiraa, Andréa Camaz Deslandesb, Fábio Yuzo Nakamurac, BrunoFerreira Vianad & Tony Meireles Santose

a Physical Education Department, President Antônio Carlos University, Barbacena, Brazilb Psychiatry Institute, Federal University of Rio de Janeiro, Rio de Janeiro, Brazilc Physical Education and Sport Center, Londrina State University, Londrina, Brazild Biomedical Engineering Program-COPPE, Federal University of Rio de Janeiro, Rio deJaneiro, Brazile Physical Education, Pernambuco Federal University, Recife, BrazilPublished online: 30 Oct 2014.

To cite this article: Bruno Ribeiro Ramalho Oliveira, Andréa Camaz Deslandes, Fábio Yuzo Nakamura, Bruno Ferreira Viana& Tony Meireles Santos (2014): Self-selected or imposed exercise? A different approach for affective comparisons, Journal ofSports Sciences, DOI: 10.1080/02640414.2014.968191

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Self-selected or imposed exercise? A different approach for affectivecomparisons

BRUNO RIBEIRO RAMALHO OLIVEIRA1, ANDRÉA CAMAZ DESLANDES2, FÁBIO YUZONAKAMURA3, BRUNO FERREIRA VIANA4 & TONY MEIRELES SANTOS5

1Physical Education Department, President Antônio Carlos University, Barbacena, Brazil, 2Psychiatry Institute, FederalUniversity of Rio de Janeiro, Rio de Janeiro, Brazil, 3Physical Education and Sport Center, Londrina State University,Londrina, Brazil, 4Biomedical Engineering Program-COPPE, Federal University of Rio de Janeiro, Rio de Janeiro, Braziland 5Physical Education, Pernambuco Federal University, Recife, Brazil

(Accepted 18 September 2014)

AbstractThe aim of this study was to compare the psychological and physiological responses of self-selected and imposed sessions ofequivalent intensities and durations and allowing to participants a free control of pace during the self-selected session.Seventeen participants completed three sessions on a cycle ergometer. Participant’s VO2Peak and lactate threshold weremeasured during an incremental exercise test. During the second and third sessions, participants could view a virtual cycliston a monitor. During the self-selected session, participants were allowed free control of the intensity and duration. Toensure that the imposed session replicated the self-selected session in intensity, participants were instructed to follow anadditional virtual cyclist, which was displayed on a monitor using the CompuTrainer 3D software. Power output andphysiological and psychological variables were recorded during the sessions. A two-way ANOVA showed no effect ofcondition for power output (P = 0.940), heart rate (HR) (P = 0.965), VO2 (P = 0.898), blood lactate (P = 0.667), FeelingScale (P = 0.877), Felt Arousal Scale (P = 0.924) and CR100 (P = 0.939). A paired t-test showed no significant difference inPhysical Activity Enjoyment Scale scores between sessions (P = 0.054). In contrast to previous studies, the self-selectedsession did not provide better affective responses than the imposed session with same intensity and duration.

Keywords: pleasure, autonomy, circumplex, aerobic exercise

Introduction

The results of previous studies have discussed a rela-tionship between adherence to aerobic exercise andacute affective responses (Ekkekakis, 2009; Lind,Ekkekakis, & Vazou, 2008; Williams, 2008) and thatself-selected exercise elicits improved affectiveresponses more frequently than does imposed exercise(Rose & Parfitt, 2007, 2012; Sheppard & Parfitt,2008). Because participants in self-selected exercisehave the freedom to choose an exercise intensity thatprovides personal satisfaction, the improved affectiveresponses may be the result of the participant’s per-ceived sense of autonomy (Deci & Ryan, 2000), well-being and enjoyment (Ekkekakis, 2009). This freedomis not observed during imposed exercise because par-ticipants must follow prescribed training variables. Inaddition to the sense of autonomy that comes with thefreedom to choose the exercise intensity, it is importantto consider the potential physiological differences that

may occur when exercise is freely chosen (self-selected) or performed at an imposed constant pace.It has been shown that exercise with a freely chosenpacemay be less physically challenging than exercise ofthe same intensity with an imposed constant pace(Lander, Butterly, & Edwards, 2009), providinganother possible explanation for the improved affectiveresponses observed in self-selected exercise sessions.

Despite the reported relationship between self-selected exercise and positive affective responses,it is possible that a participant’s lack of knowledgeabout how to adjust their exercise session maylead them to exert at intensities or for durationsthat are inappropriate for their fitness level(Johnson & Phipps, 2006). However, in a long-itudinal study of sedentary women enrolled in anexercise programme with self-selected intensity,Parfitt, Alrumh, and Rowlands (2012) showedthat the time required to reach the ventilatory

Correspondence: Tony Meireles Santos, Physical Education, Pernambuco Federal University, Recife, Brazil. E-mail: tony.meireles@ufpe.brPresent address of Bruno Ribeiro Ramalho Oliveira is Psychiatry Institute, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.

Journal of Sports Sciences, 2014http://dx.doi.org/10.1080/02640414.2014.968191

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threshold increased. This supports the use of aself-selected strategy for the improvement of phy-sical fitness because exercise performed at inten-sities above the ventilatory threshold negativelyinfluences the affective responses. Therefore, anincrease of ventilatory threshold allows an indivi-dual to exercise at higher intensities while main-taining positive affective responses.

To confirm the effects of self-selected exercise onaffective responses, several studies have comparedthe benefits of both self-selected and imposed exer-cise strategies (Lind et al., 2008; Parfitt, Rose, &Markland, 2000; Rose & Parfitt, 2007). However,these studies compared self-selected and imposedexercise sessions that differed in intensity.Furthermore, these studies used standardisedimposed durations (≈ 20 min), thus allowing parti-cipants to self-select only the intensity of their exer-cise. Because intensity can widely influence affectiveresponses (Ekkekakis, Hall, & Petruzzello, 2008),this variable must be equalised to compare theaffective responses elicited by self-selected andimposed exercise (Ekkekakis, 2009). In addition,in the aforementioned studies (Lind et al., 2008;Parfitt et al., 2000; Rose & Parfitt, 2007), exerciseintensity could be adjusted at specific times. Forexample, in the study by Rose and Parfitt (2007),participants could request a change of intensityevery 5 min, changing the natural and spontaneouspacing that typically occurs during exercise.Because pacing is adjusted continuously duringexercise (St Clair Gibson et al., 2005), this strategyis limiting, especially because it was performed atthe verbal command of the participants and exe-cuted externally by the investigator responsible forthe activity.

Therefore, previous findings demonstratingimproved affective responses during self-selectedcompared to imposed exercise sessions have notbeen adequately tested, raising questions aboutthe conclusions that have heretofore been drawn.The aim of this study was to compare the psycho-logical responses of participants during self-selected and imposed exercise sessions of equiva-lent intensities and durations. In addition, physio-logical responses were measured to compare themetabolic effects of these exercise sessions.Methodological aspects described (previouslydefined duration, pacing adjustment every 5 minand differing intensities) raise questions about thisrelation. Despite these questions, however, andbased on the assumption that there are psycholo-gical benefits to a perceived sense of autonomy, itwas hypothesised that self-selected exercise wouldelicit improved affective responses and that thephysiological responses would be similar in bothexercise sessions.

Methods

Participants

Eighteen men, ages 18 to 40 years old and recruitedfrom a university, were invited to participate in thisstudy. Participants with no musculoskeletal injuriesand a resting blood pressure of <140/90 mmHg wereclassified as “low risk” (ACSM, 2010). Participantswho used medications during the study period orperformed self-selected exercise with a duration<10 min were excluded from the study. Of the 18participants enrolled, one was excluded for failing tocomplete all of the sessions. The research protocolwas approved by the Ethics Committee on HumanResearch at GF University (protocol #160.2011).

Experimental design

Participants completed a total of three exercise ses-sions on a cycle ergometer (RacerMateCompuTrainer, Seattle, USA). Prior to the firstexercise session, the participants signed a consentform, completed a risk stratification questionnaire(ACSM, 2010) and were instructed about the meth-odological procedures and the differences betweenimposed and self-selected exercises. Participantswere asked about their physical activity habitsregarding the type of exercise they usually per-formed: no exercise, self-selected exercise, imposedexercise or both (self-selected and imposed exer-cise). For each participant, resting heart rate (HR),blood pressure and anthropometric variables wererecorded and an incremental exercise test was per-formed to determine the lactate threshold (LT), peakoxygen consumption (VO2Peak), peak HR and peakpower. During the second and third sessions, theparticipants performed a self-selected and animposed exercise, respectively. In the self-selectedexercise session, participants were allowed to selectthe intensity and duration of their exercise. Theimposed exercise, performed during the third ses-sion, was identical to the self-selected exercise per-formed during the second session. The participantswere not informed about the intensity or duration ofthe activity during either session and were instructedto exercise at a continuous pace. Physiological andpsychological variables were recorded before, duringand after each exercise session. The power outputwas recorded using the CompuTrainer 3D software(RacerMate 3D Software, Seattle, USA). The inter-val between exercise sessions was no less than twoand no more than 7 days.

Anthropometric measurements. Body mass and heightwere measured (Filizola model 31, Filizola S.A., SãoPaulo, Brazil) to determine body mass index for eachparticipant. Body fat percentage was estimated by

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measuring skinfold thickness (chest, thigh andabdominal) using a skinfold calliper (Slim Guide,Rosscraft Innovations, Inc., Vancouver, Canada).The recommendations of the American College ofSports Medicine (ACSM, 2010) were followed fortechnical procedures.

Incremental exercise test. Resting HR and blood pres-sure were recorded for each participant after lying ina supine position for 10 min. To measure LT invenous blood, the initial power output was set at 50watts (W) and was increased by 30 W every 4 min, aspreviously recommended (Yoshida, 1984). To main-tain the power output selected for each test stage, theergometer cycle modifies the resistance according tothe cadence; participants were instructed to maintaina cadence between 70 and 90 rpm. A blood sample(25 μL) was collected from the earlobe after the first3.5 min of each test stage to measure the bloodlactate concentration (Yellow Springs 1500 Sport,YSI Inc., Ohio, USA). The exercise test was per-formed until the participant experienced volitionalexhaustion. The LT was determined using the max-imal distance method (Cheng et al., 1992; Machado,Nakamura, & Moraes, 2012). The ventilatory vari-ables were recorded using a gas analyser (CortexMetalizer II, Cortex Biophysik GmbH, Leipzig,Germany), after performing the manufacturerrecommended calibration procedure, and the aver-age of the last three values recorded was used todetermine the VO2Peak. The HR was continuouslyrecorded during the test (RS800CX, Polar ElectroOY, Kempele, Finlândia).

Exercise sessions. In the self-selected exercise session,participants determined the intensity and duration oftheir exercise. The following instructions were givento the participants: “You should perform exercise ofa continuous nature. The intensity and duration ofthe exercise will be defined by you and none of thetraining variables will be imposed on you in thisexercise session.” Thus, the continuous exercisewas performed at a freely chosen pace. Participantswere allowed to change the rear and/or front gearsand the pedal cadence. The time at which thesechanges were made, as well as the gears used, wasrecorded by the researcher overseeing the test.During the exercise session, participants were ableto view a virtual cyclist on a computer monitor usingthe CompuTrainer 3D software (RacerMate 3DSoftware, Seattle, USA); however, they could notview the data recorded by the software (e.g. poweroutput, speed, rpm, time). The 200 mile, software-generated, virtual track was completely flat andappeared to be an open loop, which prevented parti-cipants from creating associations between the num-ber of laps completed and the end of the exercise

session. The length of the track ensured that theparticipant initiated the end of the exercise sessionand was not influenced by the end of the virtualtrack.

The imposed exercise session, performed duringthe third visit, replicated the self-selected exercisesession, performed during the second visit. As inthe self-selected exercise session, a computer moni-tor, placed in front of the participant, displayed atrack with two virtual cyclists positioned side-by-side, one representing the participant during thecurrent, imposed exercise session (cyclist number1) and the other representing, and performed by,the participant during the self-selected exercise ses-sion (cyclist number 2). Participants were instructedto keep both cyclists, number 2 and number 1, side-by-side during the course of the exercise session.Researchers controlled the gears and changed themin the same manner and at the same time that theparticipant did during the self-selected exercise ses-sion. To ensure that the exercise duration was thesame for both sessions, participants were instructedto finish the imposed exercise session after receivinga command from the researcher overseeing the ses-sion. Participants could end the exercise session ear-lier, however, if they experienced any cardiovascularor pulmonary discomfort and/or musculoskeletalpain. Participants were not informed that the twoexercise sessions would be similar to avoid influen-cing participants’ perceptions prior to the exercisesession.

Psychological and physiological measurements. TheCategory Ratio (CR100) scale was used to measurethe rating of perceived exertion (RPE) (Borg & Borg,2001). Measures of arousal and valence were used toscore affective responses before, during and after theexercise sessions. Arousal was measured using theFelt Arousal Scale (FAS), which consists of six itemsscored on a scale from 1 (Low arousal) to 6 (Higharousal) (Svebak & Murgatroyd, 1985). Valence wasmeasured using the Feeling Scale (FS), which con-sists of 11 items scored on a scale from −5 (Verybad) to +5 (Very good) (Hardy & Rejeski, 1989).The Physical Activity Enjoyment Scale (PACES), abipolar scale with 18 items rated on a scale from 1 to7, was used to measure perceived enjoyment(Kenzierski & DeCarlo, 1991). A Portuguese versionof PACES was used after a back translation wasperformed (Beaton, Bombardier, Guillemin, &Ferraz, 2000). A pilot study from our researchgroup, with 9 participants performing aerobic exer-cise in a cycle ergometer, showed an averageCronbach’s alpha coefficient of 0.91. The FS andFAS affective measures were selected because of thepsychological construct targeted in the present study(core affect), as well as their simplicity, validity,

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reliability and practical application (single-itemscale).

Five minutes before beginning an exercise session,participants completed the FAS and FS. Restingblood lactate concentration was measured immedi-ately before each exercise session. During the exer-cise session, physiological (HR) and psychologicalvariables (FS, FAS and CR100) were measured atminutes 4, 8, 13, 19, 22, 27, 33, 36, 42, 49, 52, 56and 63. Blood lactate concentration was measured atminutes 4, 8, 13, 19, 27, 36, 49 and 56.Measurements were taken at non-standardisedtimes to prevent the participants from associatingthe measurement times with the exercise duration.The power output and the VO2 were continuouslymeasured during the exercise sessions. After theexercise sessions, participants completed the FSand FAS (0, 5 and 15 min post-exercise), thePACES (10 min post-exercise to allow participantsto leave the cycle ergometer and remove the gasanalyser mask) and the CR100 scale (15 min post-exercise), to measure the session RPE (Kilpatrick,Robertson, Powers, Mears, & Ferrer, 2009). Theblood lactate concentration was measured immedi-ately after the exercise session (0 min post-exercise).

Statistical analysis. Because the exercise duration wasdifferent for each participant, the duration and allcollected variables were divided into quartiles toreduce and equalise the data to four mean values.For example, a participant who exercised for 63 min,with a total of 13 time point measurements, had anaverage of 3–4 measurements for each quartile. Aftertesting the normality of the data, a two-way ANOVAwas performed to compare the effects of conditionand time, with repeated measures for the time factor.The Mauchly’s sphericity test was performed and theGreenhouse–Geisser correction was applied whensphericity was not found. The PACES scores,which were measured only once after each exercisesession, were compared using a paired t-test.Statistical significance was established at P < 0.05.For the post hoc analysis, the significance was cor-rected by dividing 0.05 by the number of time pointsfor each variable, yielding the following significancevalues: HR, FS and FAS (P = 0.006); blood lactate(P = 0.008); CR100 (P = 0.01); and power output,pedal cadence and VO2 (P = 0.012). To determinethe magnitude of the differences between self-selected and imposed exercise on FS, FAS andPACES, we used an effect size analysis with theself-selected session as the reference condition. Thestandardised mean difference (SMD) was inter-preted as recommended by Hopkins (Hopkins,2002). The FS and FAS results were analysedusing the circumplex model of affect (Russell,1980) as described by Ekkekakis and Petruzzello

(2002). The analyses of significance were performedusing SPSS software v. 20 (SPSS, Inc., Chicago,USA), and the effect size analyses were performedusing Stata software v. 12 (StataCorp LP, CollegeStation, USA).

Results

Descriptive results

The participants’ characteristics are reported inTable I. All participants were physically active withthe usual type of exercise reported as follows: 9 self-selected exercise, 4 imposed exercise and 4 both self-selected and imposed exercise. Power outputshowed a significant time effect (F(1.907, 61.020) =23.152, P < 0.001, ƞ2 < 0.001, ɛ = 0.636); however,there was no significant interaction (F(1,907, 61.020) =0.003, P = 0.996, ƞ2 < 0.001, ɛ = 0.636) or effect forcondition (F(1, 32) = 0.006, P = 0.940, ƞ2 < 0.001,ɛ = 0.636). Similarly, the pedal cadence showed asignificant time effect (F(1.799, 53.983) = 5.789,P = 0.007, ƞ2 = 0.162, ɛ = 0.600) but no significantinteraction (F(1.799, 53.983) = 0.673, P = 0.499,ƞ2 = 0.022, ɛ = 0.600) or effect for condition (F(1, 30)

= 0.281, P = 0.600, ƞ2 = 0.009, ɛ = 0.600). Theseresults are shown in Figure 1.

Participants exercised at an average intensity of56.2% of peak power (s = 14.1%; minimum = 33.4%,maximum = 86.0%) for an average duration of38.9 min (s = 14.8 min; minimum = 19.1,maximum = 63.0 min).

Physiological variables

There was no significant HR interaction (F(3.362,

107.598) = 0.219, P = 0.902, ƞ2 = 0.007, ɛ = 0.480)or effect for condition (F(1, 32) = 0.002, P = 0.965,ƞ2 < 0.001, ɛ = 0.480) although there was a signifi-cant effect for time (F(3.362, 107.598) = 209.335,

Table I. Participant’s characteristics.

Variables Mean (s)

Age (years) 31 (7)Height (cm) 173.6 (4.7)Body mass (kg) 72.4 (7.0)Body mass index (kg · m−2) 24.0 (1.9)% body fat 9.6 (4.7)HRPeak (bpm) 175 (13)LT (W) 164.4 (29.9)LT (W · kg−1) 2.3 (.5)LT (% peak power) 61.4 (3.5)Peak power (W) 268.6 (51.6)Peak power (W · kg−1) 3.7 (.8)VO2Peak (mL · kg−1 · min−1) 48.7 (9.7)

Note: HRPeak – peak heart rate; LT – lactate threshold; W – watts;VO2Peak – peak oxygen consumption.

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P < 0.001, ƞ2 = 0.867, ɛ = 0.480). Oxygen consump-tion showed no significant interaction (F(1.783,

46.360) = 0.368, P = 0.670, ƞ2 = 0.014, ɛ = 0.594)or effect for condition (F(1, 26) = 0.017, P = 0.898,ƞ2 = 0.001, ɛ = 0.594) but did show a significanttime effect (F(1.783, 46.360) = 38.490, P < 0.001,ƞ2 = 0.597, ɛ = 0.594). Blood lactate concentrationshowed no significant interaction (F(1.587,

50.786) = 0.030, P = 0.946, ƞ2 = 0.001, ɛ = 0.317)or effect for condition (F(1, 32) = 0.189, P = 0.667,ƞ2 = 0.006, ɛ = 0.317). Similar to HR and oxygenconsumption, blood lactate concentration did showa significant time effect (F(1.587, 50.786) = 14.445,P < 0.001, ƞ20.311, ɛ = 0.317). These results arereported in Table II.

Psychological variables

The FS results showed no statistically significantinteraction (F(3.621, 115.864) = 0.102, P = 0.975,ƞ2 = 0.003, ɛ = 0.517) or effect for either condition(F(1, 32) = 0.024, P = 0.877, ƞ2 = 0.001, ɛ = 0.517)or time (F(3.621, 115.864) = 3.511, P = 0.012,ƞ2 = 0.099, ɛ = 0.517). The SMD for FS are

reported in Table III. The FAS results also showedno significant interaction (F(3.204, 103.783) = 0.978,P = 0.411, ƞ2 = 0.030, ɛ = 0.463) or effect for

Table II. Comparison of physiological variables of self-selectedand imposed exercise sessions.

ConditionsPost hoc t

Self-selected Imposed(within differences

Variables Mean (s) Mean (s) t for both conditions)

HRPre 62.0 (11.5) 65.5 (9.2) 0.54 AllQ1 117.4 (17.9) 118.8 (19.1) 0.21 Pre to Q4;

Post 5, 15Q2 127.3 (20.4) 127.2 (22.6) 0.01 Pre; Q1; Q4;

Post 5, 15Q3 136.2 (19.6) 136.9 (22.0) 0.11 Pre; Q1;

Post 5, 15Q4 139.8 (20.7) 138.6 (24.5) 0.19 Pre; Q1; Q2;

Post 5, 15Post 0 133.4 (22.9) 130.4 (25.7) 0.47 Pre; Post 5, 15Post 5 81.9 (15.0) 82.3 (16.2) 0.06 Pre to Post 0Post 15 82.1 (11.6) 82.3 (13.8) 0.03 Pre to Post 0

VO2

Q1 23.2 (5.9) 23.9 (7.1) 0.22 AllQ2 28.8 (7.8) 28.3 (8.8) 0.17 Q1; Q4Q3 31.4 (8.0) 30.6 (8.7) 0.25 Q1Q4 31.5 (7.4) 30.6 (8.7) 0.28 Q1; Q2

LactatePre 1.0 (.3) 1.2 (.4) 0.28 Q3 to Post 0Q1 1.6 (1.1) 1.7 (1.3) 0.25 Q3; Q4Q2 2.0 (1.5) 2.2 (1.8) 0.34 –

Q3 2.5 (1.9) 2.8 (2.3) 0.53 Pre; Q1Q4 3.0 (2.5) 3.2 (3.0) 0.31 Pre; Q1Post 3.0 (2.7) 3.3 (3.1) 0.44 Pre

Note: Q – quartile.

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Figure 1. Mean and standard deviation (s) of power output andpedal cadence in each quartile for self-selected and imposed exer-cise sessions. PP: mean peak power; LT: mean lactate threshold;Q1 was different from all quartiles for power output in bothconditions.

Table III. Magnitude of the differences between affectiveresponses in self-selected and imposed conditions.

Affective variables SMD CI95% Classification

FSPre 0.103 (−0.570 to 0.775) TrivialQ1 0.260 (−0.415 to 0.936) SmallQ2 −0.093 (−0.765 to 0.580) TrivialQ3 0.066 (−0.607 to 0.738) TrivialQ4 0.098 (−0.575 to 0.770) TrivialPost 0 0.067 (−0.606 to 0.739) TrivialPost 5 −0.065 (−0.738 to 0.607) TrivialPost 15 0.067 (−0.605 to 0.739) TrivialPooled SMD 0.063 (−0.175 to 0.301) Trivial

FASPre 0.211 (−0.463 to 0.885) SmallQ1 0.245 (−0.430 to 0.920) SmallQ2 0.041 (−0.631 to 0.713) TrivialQ3 0.513 (−0.171 to 1.197) SmallQ4 0.204 (−0.470 to 0.878) SmallPost 0 −0.352 (−1.029 to 0.326) SmallPost 5 −0.244 (−0.919 to 0.431) SmallPost 15 −0.187 (−0.861 to 0.487) TrivialPooled SMD 0.053 (−0.186 to 0.292) Trivial

Note: SMD – standardised mean difference; Q – quartile; CI95% –

95% confidence intervals.

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condition (F(1, 32) = 0.009, P = 0.924, ƞ2 < 0.001,ɛ = 0.463); however, a significant time effect wasobserved (F(3.204, 103.783) = 20.758, P < 0.001,ƞ2 = 0.393, ɛ = 0.463). The SMD for FAS betweenself-selected and imposed exercise sessions areshown in Table III. Finally, the CR100, similarly,showed no significant interaction (F(2.229, 71.335)

= 0.433, P = 0.672, ƞ2 = 0.013, ɛ = 0.557) or effectfor condition (F(1, 32) = 0.006, P = 0.939,ƞ2 < 0.001, ɛ = 0.557); however, there was a signifi-cant effect for time (F(2.229, 71.335) = 34.911,P < 0.001, ƞ2 = 0.522, ɛ = 0.557). These resultsare reported in Table IV. Although the differencein the PACES scores between self-selected(95.8 ± 14.5) and imposed (102.4 ± 13.8) exercisewas not statistically significant (t = 2.0 andP = 0.054), there was a small effect size(SMD = 0.466; CI95% = −0.216 to 1.148) indicatinga trend towards higher PACES scores for imposedexercise.

The circumplex model showed a similar pattern inboth experimental conditions (self-selected andimposed). In both exercise sessions, the affectivestates were Unactivated Pleasant in the early stages(pre and Q1), Activated Pleasant in the intermediateand end stages (Q2, Q3 and Q4) and, again,Unactivated Pleasant in the post-exercise stages (0,5 and 15 min). These results are shown in Figure 2.

Discussion

The objective of the present study was to comparethe physiological effects and affective responses ofparticipants performing self-selected and imposedexercise sessions of equal intensities and durationsthat allowed continuous adjustment of pace. To ourknowledge, no other study has equalised the inten-sities of the self-selected and imposed exercise

sessions while allowing participants to control theexercise duration and continuously modify theirpace. The main finding of this study is that theexercise condition had no effect on affectiveresponses. The results indicate that an imposed exer-cise session can elicit affective responses similar tothose observed in self-selected exercise sessions.

Table IV. Comparison of psychological variables of self-selectedand imposed exercise sessions.

Conditions

Self-selected Imposed Post hoc t(within differences

Variables Mean (s) Mean (s) t for both conditions)

CR100Q1 23.7 (12.0) 26.2 (13.4) 0.40 AllQ2 33.9 (11.7) 36.1 (18.8) 0.35 Q1; Q3; Q4Q3 42.4 (17.7) 42.0 (20.8) 0.07 Q1; Q2Q4 47.4 (22.7) 47.2 (25.7) 0.03 Q1; Q2Post 41.6 (16.7) 39.6 (19.1) 0.31 Q1

FSPre 1.9 (1.9) 2.1 (1.7) 0.27 –

Q1 2.0 (1.3) 2.3 (1.7) 0.40 –

Q2 2.0 (1.4) 1.8 (1.6) 0.21 –

Q3 1.6 (2.0) 1.6 (2.4) 0.03 –

Q4 1.4 (2.4) 1.5 (2.5) 0.27 –

Post 0 2.2 (1.7) 2.3 (1.8) 0.18 –

Post 5 2.5 (1.8) 2.4 (2.1) 0.18 –

Post 15 2.7 (1.8) 2.8 (1.7) 0.18 –

FASPre 2.2 (1.3) 2.4 (1.3) 0.29 Q2 to Post 0Q1 3.2 (1.0) 3.4 (1.1) 0.63 Pre; Q2; Q3Q2 3.9 (.8) 3.9 (1.1) 0.02 Pre; Q1; Post 5, 15Q3 3.9 (.8) 4.3 (1.1) 1.20 Pre; Q1; Post 5, 15Q4 4.0 (1.2) 4.3 (1.2) 0.57 Pre; Post 5, 15Post 0 3.5 (.9) 3.2 (1.5) 0.86 PrePost 5 3.0 (1.3) 2.7 (1.5) 0.72 Q2; Q3; Q4Post 15 2.8 (1.3) 2.5 (1.5) 0.57 Q2; Q3; Q4

Note: Q – quartile.

Self-selected Imposed6.0

ActivatedUnpleasant

270° 270°

90° 90°

180° 180°0° 0°

Q4 Q2

Q1P1

P2

P3

Pre

Q3

Q4Q2

Q1P1

P2

P3Pre

Q3

ActivatedPleasant

UnactivatedUnpleasant

UnactivatedPleasant

ActivatedUnpleasant

ActivatedPleasant

UnactivatedUnpleasant

UnactivatedPleasant

3.5

1.0

–5.0 5.0

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–2.5 2.50.0 –5.0 5.0

FS

–2.5 2.50.0

FAS

Figure 2. Circumplex model of affect during self-selected and imposed exercise sessions. Q: quartile; P1: post 0 min; P2: post 5 min; P3:post 15 min.

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Therefore, the exercise mode (self-selected orimposed) is not the key factor to consider whenprescribing aerobic exercise; rather, the intensityand duration of the exercise are more important.Despite this finding, however, it is important to con-sider several other aspects that may influence anindividual’s personal satisfaction with exercise, suchas environmental conditions (Coon et al., 2011) andsocio-economic and cognitive factors (Rhodes,Warburton, & Murray, 2009).

Previous studies (Parfitt, Rose, & Burgess, 2006;Parfitt et al., 2000; Rose & Parfitt, 2007, 2012;Sheppard & Parfitt, 2008) limited their findings bythe differences in the intensity of both self-selectedand imposed exercise sessions. They therefore com-pared exercise conditions that were essentially differ-ent. Most studies have consistently demonstratedbetter affective responses for self-selectedapproaches, possibly because these studies havecompared different exercise intensities. The presentstudy placed participants in a real self-selected con-dition in which they could adjust their pacing strat-egy continuously throughout the exercise session.Other studies (Parfitt et al., 2006, 2000; Rose &Parfitt, 2007, 2012; Sheppard & Parfitt, 2008) haveallowed participants only partial control by permit-ting them to make adjustments every 5 min. Thiscondition compromises the findings observed inthese studies.

One of the concepts that ostensibly supports theuse of self-selected exercise is the sense of perceivedautonomy (Deci & Ryan, 2000). Our results suggestthat perceived autonomy has no influence on affec-tive responses to imposed or self-selected exerciseand that an imposed exercise regimen of an intensityand duration appropriate to the individual can pro-duce affective responses that are similar to thoseobserved during self-selected exercise. However, aself-selected exercise session can be used to rapidlyidentify the optimal exercise intensity that will pro-duce positive affective responses in an individual.This could be attributed to the wide range intensitiesthat the individuals may select during self-selectedexercise sessions. In contrast, during imposed exer-cise sessions, participants usually perform at a con-stant pace. In a previous study, Johnson and Phipps(2006) suggested that self-selected exercise shouldbe avoided because individuals may under- or over-estimate their actual physical fitness. The partici-pants in the present study, however, performedself-selected exercise sessions at an average intensityof 56.2% (s = 14.1%) of peak power and for anaverage duration of 38.9 min (s = 14.8 min), whichare within the range recommended by the ACSM foraerobic exercise (ACSM, 2010). It is important toconsider that 13 of the 17 participants in the presentstudy had experience with self-selected training

sessions, and thus, results may be different forother populations, including people who are seden-tary or perform only imposed exercise. Additionally,few studies have investigated the chronic effects ofself-selected exercise on physiological variables(Butcher et al., 2008; Parfitt et al., 2012). Althoughthere is little knowledge about the chronic effects ofself-selected exercise on physical fitness variables, ithas been postulated that any physical activity is pre-ferable to a sedentary lifestyle (Chodzko-Zajko et al.,2009).

Although it was not the focus of this study, sig-nificant effects of time for power output, physiologi-cal variables (HR, VO2 and blood lactate) andpsychological variables (FAS and CR100) werefound. These results indicate that the power outputchanges, initiated by participants during the self-selected exercise modulated their physiological andpsychological responses. This result could beexplained by the Dual-Mode Theory, which pro-poses that exercise intensity mediates the influenceof cognitive and interoceptive cues on affectiveresponses (Ekkekakis, 2003). Aerobic trainingrecommendations for continuous exercise usuallyinclude a fixed intensity for the exercise session(ACSM, 2010; Garber et al., 2011; Santos, Gomes,Oliveira, Ribeiro, & Thompson, 2012). Our results,however, suggest that aerobic exercise practitionersprefer to change their power output during aerobicexercise sessions. Future aerobic training recom-mendations should consider including pacing char-acteristics similar to those used in this study.Furthermore, it is possible that an individual couldmodify an imposed exercise regimen to better meettheir needs. Therefore, it is possible that a mixedapproach (imposed and self-selected) could be abeneficial approach to developing of future aerobictraining recommendations.

The present study has limitations that should beconsidered when interpreting the results. Womenwere not included in this study because of the pos-sible influence of the menstrual cycle hormones onphysiological and affective responses. The use of amask for gas analysis, the blood collection and theapplication of scales and questionnaires may havereduced the external validity of the results.However, these measurements were performed dur-ing both experimental conditions, thus ensuring theequality of the self-selected and imposed conditions.Moreover, the use of both experimental conditionsincreased the internal validity of the study. Theimposed exercise session utilised a “game model”in which the participant followed an avatar that wasvirtually represented on a computer monitor. The“game model” may have increased the dissociativethought, possibly as a result of lower attentionalfocus on physical sensations and higher attentional

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focus on the non-exercise related stimuli, leading toan increase in the affective responses of participants(Rose & Parfitt, 2010). This potential influence ofthe “game model” on the enjoyment responses isconsistent with the results for the PACES score(P = 0.054 and small effect size). However, despitethis limitation, the methodology used in this studyallowed participants free control of their pace, acritical limitation of previous studies. The criteriaused by each participant to end the self-selectedexercise session (for example, fatigue, discomfort,pain or thirst) were not determined. Future studiesshould include this information because it could helpfitness professionals to understand an individual’sreasons for ending an exercise session. Althoughthe inclusion of an imposed exercise session per-formed at a constant pace could have providedimportant results, previous studies have alreadyshown negative affective responses under these con-ditions when compared to self-selected exercise ses-sions (Rose & Parfitt, 2007, 2012; Sheppard &Parfitt, 2008). Finally, the use of an experimentaldesign with no randomisation of the exercise ses-sions is a limitation of the study. This design, how-ever, was necessary to equalise the experimentalconditions.

Conclusion

In summary, when exercise intensity and durationare equalised, the strategy chosen for the aerobicexercise session (self-selected or imposed) does notinfluence the psychological responses of participants.The improved psychological responses for self-selected exercise reported in previous studies arelikely due to optimising physiological adjustmentsperformed by each participant rather than the psy-chological effects of perceived autonomy. In the pre-sent study, each participant had only one self-selected exercise session. Future studies shouldinvestigate the effects of several self-selected exercisesessions on the affective responses of participants. Itis possible that participants will self-select differentintensities and durations in each exercise session,which could lead to different affective responsesfrom those observed in the present study.

Funding

The authors acknowledge the financial support fromCNPq.

Conflict of interest

The authors declare that they have no conflict ofinterests.

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