THE EFFECTS OF EXERCISE TRAINING ON

MENTAL WELL-BEING IN THE NORMAL POPULATION:

A CONTROLLED TRIAL

JENNIFER MOSES, ANDREW STEPTOE,* ANDREW MATHEWS and SARA EDWARDS

(Received 14 April 1988; accepted in revised form 20 July 1988)

Abstract-This study was designed to compare the effects of two aerobic training programmes of differing intensities on mood and mental well-being with those of a credible attention-placebo condition. One hundred and nine sedentary adult volunteers from the local population were assigned to four conditions: high intensity aerobic training, moderate intensity aerobic training. attention-placebo and waiting list. Training was carried out over a 10 week period. Subjects were assessed before and after training with psychological measures and the I2 min walk-run test. and follow-up evaluations were undertaken after 3 months. Ninety-four subjects began the programme and the adherence rate averaged 80%. with no significant differences in number of drop-outs between conditions. Appropriate changes in estimated maximum oxygen consumption were observed in the three active conditions with the I2 min walk-run test. Psychological benefits were seen with the moderate exercise condition but not in the high exercise or attention- placebo conditions. These effects were manifest immediately after training on measures of tension/anxiety and confusion, and at follow-up on measures of perceived coping ability. The mechanisms underlying this pattern of results are discussed and the relative importance for health of vigorous activity and physical fitness is considered.

INTRODUCTION

THE VIEW has emerged over recent years that exercise training has a positive effect on mood and mental well-being [ 11. This pattern is of clinical interest for a number of reasons. Firstly, exercise training may be useful in the management of depressed patients [2] and in the reduction of psychological distress in the normal population (31. Secondly, it has been suggested that physical training helps people to cope with stress more effectively, and to recover from the adverse effects of negative life events [4, 51. Finally, exercise has become established as a method of reducing

coronary risk [6] and treating hypertension [7]. However, adherence to exercise programmes tends to be poor [8]. If lack of enjoyment is one of the factors underlying poor adherence, studying the effects of exercise on well-being might permit the development of training methods that encourage more persistent behaviour change.

Much of the early evidence relating physical activity and fitness with improved mental well-being in normal populations was correlational or cross-sectional in nature, with non-random assignment of subjects and other methodological problems [9-111. Data from randomised trials comparing exercise with no treatment have been less consistent [12-141. Several studies contrasting exercise training with conditions designed to control for subject expectancies and group participation have also been reported. McCann and Holmes [3] compared aerobic

‘Address correspondence to this author at: Department of Psychology, St George’s Hospital Medical School, University of London. Cranmer Terrace. Tooting, London SW17 ORE. U.K.

47

48 JENNIFER MOSES el al.

training with relaxation and found that depression was only reduced in the former. Unfortunately, there were more supervised classes in the exercise condition, so differences in the amount of attention paid to the groups may have been present. This problem also confounds Goldwater and Collis’s comparison of high and low intensity exercise training [15]. Long [16] assigned subjects to aerobic and stress inoculation groups, and found that both conditions were associated with a greater decrease in self-reported tension and improvement in self-efficacy than waiting list control. Pre-treatment differences in aerobic fitness between groups render this study difficult to interpret. No differences in anxiety, depression and other moods were observed by Sinyor et al. [17] in a comparison of aerobic training, anaerobic training and waiting list control groups. Improvements in perceived self-mastery were found in the aerobic condition, but pre-treatment differences were present on this measure. A further comparison of exercise training with relaxation and no treatment has been reported by Roth and Holmes [5]. Subjects in this study were selected on the basis of high levels of recent negative life events. Aerobic training was associated with greater reductions in depression than the other conditions. but there were no differences in measures of anxiety or physical symptoms.

The controlled studies on normal populations have evidently not shown a clear pattern of results. Their generalisability is also uncertain. Most have used college students as subjects, and these may not be representative of the population at large. Furthermore, the issue of appropriate control procedures has not been resolved satisfactorily. It has been suggested that the positive psychological effects of exercise are not due to increased activity or fitness, but to a greater sense of mastery, positive expectancies and the non-specific effects of group participation [13], counselling and socialisation [14] or placebo responses ilS]. Another factor that must be taken into account is the type of psychological measure used, since many of the more positive observations have emerged not on mood assessments, but measures of perceived self-efficacy and ability to cope [13, 16, 171.

The present study was designed to assess the effects of aerobic exercise on psychological well-being in the light of these considerations. Volunteers were recruited from the local population and were screened for current depression. previous psychiatric disturbance, adverse medical history and high levels of physical activity. They were assigned to experimental conditions at random within the constraints of matching on important factors such as age, sex, habitual exercise level and time of year. In addition to testing the effectiveness of aerobic training per

se, two alternative hypotheses were investigated: (1) The psychological responses to exercise training are due to the non-specific effects of participating in a structured programme in which subjects progress towards physical achievement goals. This hypothesis was tested by comparing aerobic training with an attention-placebo condition developed to be comparable in terms of programme structure and intensity. Expectancies in the different conditions were carefully assessed. (2) The psychological responses to exercise training are due to increases in levels of physical activity rather than to improved aerobic fitness. This distinction is important, since LaPorte and co-workers [19, 201 have argued that health benefits may arise from increased physical activity rather than greater fitness. Leon et ul. [21] observed that moderate leisure time physical activity was

Effects of exercise on mental well-being 49

associated with reduced coronary morbidity and mortality, but that high levels of exercise conferred no additional benefit. Aerobic fitness and the responses to training appear to have strong hereditary components [22], so it is questionable whether increased fitness is an appropriate target for population studies. The issue was tested by comparing an aerobic conditioning programme with a moderate intensity aerobic programme that was expected to produce only marginal changes in cardiorespiratory fitness. It was reasoned that if psychological benefits accrued from increased fitness itself, then they should only be present in the high intensity condition. If, however, they result from increased activity levels,-then they-might be present in both varying extent.

aerobic programmes, possibly to a

METHODS

Design Sedentary adult volunteers from the local population were assigned to one of four conditions: high

exercise, moderate exercise, attention-placebo and waiting list. Two groups were run in each condition. one beginning in the winter and the second in the summer months. Training was carried out over a 10 week period and consisted of one supervised and three unsupervised sessions per week in each condition. Subjects were assessed individually in the laboratory before training with psychological and psychophysiological evaluations and a submaximal exercise test. and after training (or an equivalent period in the waiting list condition) with psychological and psychophysiological measures. The active training groups also carried out a Cooper 12 min walk-run test at the beginning and end of training in order to estimate changes in fitness. Subsequently, subjects in the waiting list condition were offered the moderate exercise programme. Participants were followed up 3 months post training. with assessments of fitness and psychological state.

Subjects Four hundred and six local residents answering advertisements about a ‘health and fitness project’

were sent a questionnaire to complete. Respondents were considered eligible to participate if they were aged 18~0, reported low levels of habitual activity. no medical problems likely to interfere with training, no hypertension. no psychiatric history, scored below 11 on the depresston subscale of the Hospital Anxiety and Depression Scale (HAD) [23] and if they were not more than 25% above their ideal weight (based on the Metropolitan Tables) [24]. More than 200 individuals were eligible. of whom 109 were invited to participate in the study. They were allocated at random to the four conditions while maintaining a balance for sex. age, weight. habitual activity level. cigarette smoking. instructor (two instructors were involved). venue (two venues were used) and time of year (summer or winter). Ninety- four subjects completed the pre-training laboratory session and began the programme in earnest; the remaining 15 people failed to participate due to scheduling difficulties or changed personal circumstances. The number of subjects in each condition at different stages of the study is summarised in Table I. The data reported here are based on 75 subjects for the pre/post-training analyses. and 58 subjects for the prel3 month follow-up’analyses. There were no significant differences in the proportion of dropouts in the four conditions.

TABLE I.-NUMBER OF SIJBJECTS IN THE FOUR EXPERIMENTAL CONDITIONS AT DIFFERENT STAGES OF THE STUDY

High exercise Moderate exercise Attention-placebo Waiting list Waiting list subjects in

moderate exercise programme

Structured sample

29 29 27 24

Pre-training

25 22 23 24 15

Post-training

18 I9 18 20 12

3 month follow-up

16 17 15

10

so JENNIFER MVSES et al.

P.~~c/~ologicnl I~IC(ISIIT~.S. The principal measures used to evaluate the effects of the experimental conditions on psychological well-being were the Profile of Mood States (POMS) 1251. and a scrics of scales developed in this project for the evaluation of perceived coping ability and physical well-being. The POMS consists of 65 adjectives. each of which is rated on a five-point scale ranging from 0 = ‘not at all’ to 4 = ‘extremely’. It has been factor and analyzed into six subscales: tension/anxiety, depression/ dejection. anger/hostility. vigouriactivity. fatigue/inertia. and confusion. The inventory was modified b! reducing the number of adjectives contrlhuting to each suhscale to six b) selecting the items that loaded most highly on each subscale according to published information on the construction of the measure. This procedure has previously been used in studies of acute psychological responses to exercise [?h].

The measure of perceived coping ability and physical well-being consisted of 36 items that were arranged in the same format as the POMS. These items were selected from the literature concerning responses to exercise. and were intended to assess coping ability, feelings of mastery and subjective changes that accompany exercise. Factor analysis with varimax rotation was performed on questionnaires completed by I02 volunteers. Three factors emerged with Eigen values greater than 2.0 and together these explained 45.2”/, of the variance. A further factor analysis wa\ performed forcing a three factor solution. and items loading > ? 0.10 were included in the final solution. The three factors are summarised in Table II. Factor I (tentatively labelled ‘perceived coping assets’. I4 items) predominantI> contain4 positive coping statements and feelings about the self. Factor 2 (labelled ‘perceived coping deficits‘, ten items) consists of negative feelings and indications of poor competence. The third factor (six items) consists of item\ concerning perceived physical status and has been labrlled ‘physical well- being’. The remaining six items from the questionnaire were excluded from the anslysis. The infernal reliability of the scales showed satisfactory levels of consistency across items and separate presentations of the questionnaire (Cronbach’a oi = 0.73). Seventy-five subjects completed the questionnaire on two occasions separated by an interval of 7-3 weeks. and the internal consistency wa\ satisfactory on both occasions (Cronbach.5 01 = 0.76 and 0.7X. respectixcly).

TARLF II.--SrRLTI I:RI1 OF S(‘-\l E\ (‘ON< FKNIYC; PtRC’FI\ ED C.OI’INC; AlSILl I Y -\NI) PrRC.1 I\‘FI) I’H’r\I(‘AI 51:\IL’5

Item Item Loading

Factor I: perceived coping assets

Self-confident 0.62 Achievin! something 0.35 Enthusiastic 0.63 OvercomIng difficulties 0.61 Uplifted t1.58 Getting close to goal\ 0.55 Proud of self 0.70 Well-organised 0.53 Elated 0.9 Competent 0.71 Invigorated 0.51 Under control O.h2 Coping 0.55 Attractive O.Jl

Factor 2: perceiced coping dcticitq

Easily irritated 0.59 Dl\treascd (1.6.5 Disappointed with self 0.19 Bothered 0.65 Calm ~0.55 Overwhelmed 0.52 Drained 0.64 Under too much pressure 0.67 Easily upset 0.5x Run down 0.50

Factor 3: phys;lcal Nell-being

Refreshed 0.42 Supple 0.60 Healthv 0.7!, Fit 0.78 Strong’ 0.64 Well 0.54

Expectations concerning the programmes were assessed with five questions. asking aubJects to what extent they believed that training would improve their level of fltnesa. health and sense of well-being, the extent to which they expected to enjoy participating and whether they would recommend the programme to a friend. Each item way rated on a five-point scale with higher scores representing more positive expectations (maximum 25).

Effects of exercise on mental well-being 51

A number of other psychological measures were also included in this study. The HAD scale [23] wa\ administered in order to screen out subjects with high initial levels of depression. Type A coronary- prone behaviour was measured using the Framingham Scale [27]. Although there are many reservations concerning questionnaire measures of type A behaviour. the Framingham Scale is the only measure to date that has been found to predict future coronary heart disease among women. The scale was scored to produce a value between 0 and I. a high score indicating type A responses. Habitual physical activity level (HAL) during occupational and leisure time was assessed using a questionnaire adapted from the study conducted by the Health Insurance Plan of Greater New York [2X]. These scales assess typical activities during the working day and in leisure time. and are each classified into four activity categories. Finally, perceived self-efficacy was assessed using the measure devised by Coppel [29].

Firnrss ,neausres. Two measures of aerobic fitness were obtained during the study. Subject< in all f&r conditions underwent a submaximal graded exercise test in the laboratory before training. Exercise was performed on a Monark 864 weight cycle ergometer while the electrocardiogram was monitored using chest leads (V4) and respiratory parameters were measured using a Vol.Ox system (Bioscience). The electrocardiogram. respiration rate, minute volume and oxygen extraction were monitored on-line by a CED/LSI mini-computer. R-R intervals were detected to an accuracy of 2 msec and converted into heart rate (in b.p.m.) for subsequent analysis. Oxygen consumption (in mlikgimin) was calculated on the basis of oxygen extraction and minute ventilation. All subjects undertook exercise at three or four work loads each for 4 min. depending on their physical status. Following trials at 2SW and SOW. the work level for the third exercise load was set at 7SW if heart rate (HR) exceeded 65% estimated maximum (HR,,,,,,) on the SOW trial, or 1OOW if heart rate was below this level. The work level for the fourth trial was decided on the following algorithm: if load 3 at 75W and heart rate > 65% HR,.,,, then load 4 was IIIOW. If load 3 at 1OOW and heart rate < 65% HR,,,,, then load 4 was 7SW. If heart rate > 65% HR,,,,,,, then load 4 was 1SOW. The exercise test was terminated if heart rate reached 80% HR ,,).,,, and no higher loads were attempted. Data from all available work loads were entered into a regression analysis in order to predict maximal oxygen uptake based on estimated maximal heart rate according to the procedures described by The American College of Sports Medicine (ACSM) [30].

The second measure of physical fitness was the Cooper 12 min walk-run test [31]. This test was completed by the three active training groups only. before and after training and was carried out on an all-weather running track. Subjects were asked to walk or run as far as they could within a I2 min period. The distance covered was measured and converted using standardized scales to a predicted maximal oxygen uptake (in mlikgimin) corrected for age and sex.

Other measures. Body weight and percent body fat were assessed. Holtain calipers were used to measure skinfold thickness from the biceps. triceps. subscapula and supra-iliac sites of the body. Two measures per site were recorded. with a third measure taken if the difference between the first readings exceeded 0.5 mm. Mean values were summed and converted to percentage body fat in relation to age and sex according to data presented by Durnin and Womersley [32].

Twining programm~ The training conditions each consisted of a IO week course with one supervised and three

unsupervised sessions per week. Each was structured so that individuals entered the schedule at a level appropriate for their initial fitness. and progressed towards more demanding levels over the programme. Sessions in all conditions included identical warm-up and coo-down exercises lasting S-10 min. but differed in the intensity of the training’phase.

H&h esercise. This condition was structured to fulfil the recommendations of the ACSM [30] that the development of cardio-respiratory fitness requirca exercising on 3-S day\ per week with IS-60 min of continuous aerobic activity at 6(~90% of HR,,;,, using large muscle groups. A walk-jog programme was devised involving continuous exercise of 30 min at an intensity sufficient to elevate HR to 7&7S% of

HR,,.,,.

Moderntr e.wrcise. This condition involved aerobic exercise at a level expected to produce only minimal improvements in cardiorespiratory fitness. being on the threshold of the criteria described by the ACSM. It was based on sessions of 20 min continuous walking or jogging at an intensity sufficient to elevate HR to 60% of HR,,,,,.

Atrention-placebo. Subject5 in this condition performed strength. mobility and flexibility exercises during the training phaTe of each session. and carried out slow. discontinuous exercise for at least 30 min at an intensity that did not elevate HR above 50% HR,,,,,,.

52 JENNIFER MOSES er al.

Subjects were provided with detailed training manuals that outlined the rationale of the programme. the structure of training and how to deal with problems that might occur. Careful attention was paid in each group to helping participants to integrate training sessions into their daily routines. Immediate and long-term goals were set in terms of improvements in endurance in high and moderate exercise conditions. and flexibility and suppleness in the attention-placebo condition. Supervised session\ were similar in intensity and duration to those in the home training programme. but involved a varied set of circuit training and pop mobility exercises. together with discussion of the programme and its goals. Subjects were taught to monitor their own HR in order to ensure that they remained within prescribed training limits during unsupervised sessions. Weekly diaries were distributed in which details of the duration of each training session were listed. together with ratings of exertion on the Borg scale [X31. These diaries were discussed at supervised training sessions and used to adjust activity levels for subjects in each condition, and to identify problems of adherence.

Procedure Potential participants who answered advertisements concerning the programme were sent general

details together with a questionnaire. The questionnaire concerned background information, smoking. disabilities. recent illnesses. dieting. reasons for wanting to participate. together with items assessing habitual physical activity. Following provisional allocation to experimental conditions. subjects attended individually for a ‘computerised fitness test’. They brought with them the complete HAD scale and. if this together with a detailed interview concerning medical and psychiatric history revealed no grounds for exclusion, they proceeded to fill in the POMS with additional scales, the Self-Efficacy Scale. Framingham type A questionnaire and HAL. Body weight was measured and skinfold thickness assessed. They also underwent a psychophysiological assessment in the laboratory during which autonomic reactions to stressful tasks were assessed; these data will be described elsewhere as they are not relevant to the main hypotheses being considered here. The subject then moved to the ergometry laboratory where the graded submaximal exercise test was carried out. Participants who still fulfilled selection criteria after these assessments were then given a detailed summary of the experimental condition to which they had been assigned. After reading this they filled out the first expectancy measure, and the schedule for the training group was described. Subjects in the waiting list condition were informed that a place in the programme was not at present available for them, but that they would be contacted in a few weeks.

Laboratory testing for each experimental group of 1 I-IX people took 2-3 weeks to complete. After this. the group met in an orientation session in which the details of the programme were described and practical questions concerning location. equipment and clothing were discussed. The first of the ten supervised sessions was conducted at a local running track, and the first 12 min test was carried out on this occasion. A second expectancy measure was completed. The post-training 12 min test was carried out during the tenth supervised session.. Subjects then returned to the laboratory for the post-training assessment over the next 2 weeks. This was similar to that conducted pre-training. except that the HAD. type A questionnaire and HAL were not re-administered. During the post-training 12 min test and laboratory session, subjects completed further ratings using the expectancy mcasurc. Subjects in the waiting list condition were recalled after an equivalent 11 week interval. They were told that space wa\ now available for them. but that in view of the delay it was ncccssary to conduct a further laboratory assessment. These people were then offered the moderate exercise programme. and were reassessed afterwards with the same psychological measures as the other groups.

Subjects in all conditions were followed up after a X-month period during vvhich no contact was made. They were administered the questionnaires containing the POMS and measures of perceived coping ability. a further assessment of HAL. and carried out a final I2 min test.

Dais reduction and analysis The six POMS and three additional scales were scored to produce responses ranging from 0 to 24.

Frequency analysis indicated that the six scales containing negative self-report items (tension/anxiety. depression/dejection, anger/hostility. fatigue/inertia, confusion and perceived coping deficits) and the physical well-being scale were negatively skewed due to a predominance of low scores. These scales were therefore log transformed before analysis.

Participants were considered to have adhered to the programme if their diary records and attendance at supervised sessions indicated that they had completed 70% of scheduled assignments. Group comparability at the beginning of the study was assessed with one-way analysis of variance. Changes in fitness and psychological measures over the course of the programme were assessed using repeated measures analysis of variance with one between-subject factor (group) and one within-subject factor (time). Changes in the three training conditions at follow-up were assessed with group as the between- subject factor and time (pre. follow-up) as the within-subject factor; in this case. those members of the waiting list condition who completed the moderate exercise training programme were included with the

Effects of exercise on mental well-being 53

original moderate exercise subjects. Diary records of home practice were analysed in terms of number of sessions per week, average exertion rating per week and average session duration in minutes, comparing weeks 1-5 with weeks 6-10 in repeated measures analyses of variance. In all analyses. the Greenhouse- Geisser procedure for correcting violations of the sphericity assumption in repeated measures analysis of variance was carried out where appropriate. In view of the preponderance of women in the study. analyses were carried out on the entire sample of women separately. However, the results were similar in the two cases, so data from the whole sample are reported here.

RESULTS

Group comparability Table III summarises the characteristics of subjects in the four experimental

conditions. There were between 12 and 15 women and four to six men in each condition, and average ages ranged from 37.7 to 39.9 yr. There were no significant differences in the proportion of men and women, age, body weight percentage body fat, the extent to which people differed from their ideal weight, HAL or HAD anxiety subscales. Scores on the HAL scales indicate low job and moderate leisure activity ievels. Mean type A scores on the Framingham scale are slightly higher than those reported by Haynes et al. [27], but did not differ between groups. There was a significant difference in depression as rated on the HAD subscale, F(3,70) = 4.37, p < 0.01. Breakdown analyses indicated that the mean depression score in the high exercise group was greater than that in the moderate exercise and attention- placebo, but did not differ from the waiting list condition. However, none of the subjects scored above the clinical threshold on the depression subscale. There were no significant differences in maximum oxygen consumption estimated from the submaximal ergometer test. There were between two and four cigarette smokers in each group.

The mean score on the expectancy measure taken at the end of the pre-training laboratory test was 20.1 (4 2.8), and did not differ significantly between groups. Ratings from the first supervised session were also high. At the end of training, expectancy ratings averaged 19.1 (+ 2.6). Again there were no differences between

TAHLE III.--GROUP CHARACTERISlICS

High Moderate Attention- exercise exercise ulacebo Waitine list

iex

Age (yr) Weight (kg) Body fat (%) Difference from ideal weight (kg) Habitual activity level

Job Leisure

Type A score (Framingham) Hospital Anxiety and

Depression Scale Anxietv

18 I9 12Fl6M 15Fl4M 31.7 39.1 68.5 62.0 27.3 28.2

+2.2 -0.5

I8 13Fi5M 39.9 63.1 28.8

-0.8

20 15Fi5M 39.4 63.8 27.1

t I .o

2.06 1.94 1.44 I .80 2.72 3.00 3.1 I 3.10 0.47 0.47 0.46 0.43

7.44 X.00 6.83 8.15 Depression

Max. oxygen consumption (ml/kg/min)

6.11 3.11 3.33 4.75 35.9 31.7 35.1 34.1

Sl JENNIFER MOSES rr al

groups, indicating that subjects rated all the training programmes highly, and that their expectations of the different conditions were similar.

Adherence to truining progrrrtnme.~

Analysis of the number of training sessions reported per week revealed a main effect of time, F( 1.44) = 19.5, p < 0.0001. As can be seen in Fig. 1, the number of sessions declined from an average of 3.48 over weeks l-5 to 3.05 in weeks 6-10. There were, however, no significant differences between the experimental conditions in this respect. In contrast. the analysis of exertion ratings yielded a main effect for group [F(2,42) = 3.83. p < O.OS]. Perceived exertion in the high exercise condition averaged 14.8, a level found by Hage 1341 to be equivalent to 70- 85% of HR,,,;,,. The attention-placebo group averaged 13.2. with an intermediate level in the moderate exercise condition (13.7). Although there was a tendency for ratings of exertion to increase from the first to second 5 weeks of training (see Fig. 1). this effect was not reliable [F(1.32) = 4.58, p = 0.077].

ADHERENCE TO TRAINING

4i

. .

11 1 ~. . ~. 20 _-

1-5 6- 10 I-5 6-10 WaeCS wee**

FK;. I.-Average number of seaion (top panel). exertion rating per session (middle panel) and session duration (bottom panel) in the three experimental condition< river week\ I-S and &IO of the training

programme.

Effects of exercise on mental well-being 55

Analysis of the duration of sessions showed main effects for group [F(2,51) = 14.2. p < O.OOOl] and time [F(1.51) = 5.67, p < 0.0251, together with a group by time interaction [F(2,_51) = 3.92, p < 0.051. As can be seen in Fig. 1. the high exercise group maintained a session length of 40 min. while the attention-placebo subjects practised their exercise for some 8 min longer. The moderate exercise group practised for a shorter time over weeks l-5, then increased the duration of sessions to a length similar to the high exercise group.

Aerobic fitness Analysis of maximum oxygen consumption estimated from the 12 min walk-run

showed the training effects expected for these experimental conditions, with a group by time interaction, F(3,.54) = 3.38, p < 0.025. These data are summarised in Fig. 2 with the results plotted as change scores for convenience. It can be seen that orderly improvements in aerobic fitness were observed. with the greatest changes in the high exercise condition and minimal change in the attention-placebo condition. An intermediate response was produced with the moderate intensity programme both by the original group and by the waiting list subjects when they entered this condition. Breakdown analyses indicated that the improvement produced by the high exercise group was significantly greater than that achieved by subjects in the attention-placebo condition 0, < 0.01). The differences between moderate and high exercise groups, and moderate exercise and attention-placebo groups. did not attain conventional levels of statistical significance 0, < 0.09 and 0.11, respectively). Analysis of exertion ratings taken at the end of the post-training run, co-varying for pre-training exertion, showed no significant difference between groups. The training effects were. largely maintained by the subjects who were retested at 3 months follow-up (F(4,72) = 5.11. p < O.OOl].

CHANGES IN AEROBIC FITNESS Cooper 12 min Test

. Attention-Placebo

Moderate exerclos (2)

Pre Port 3m

FIG. 2.-Mean change in estimated maximum oxygen consumption calculated from performance of the 12 min test (311 pre- and post-training and at 3 months follow-up. The moderate exercise group (1) and the waiting list subjects who subsequently participated in the moderate exercise condition (2) are plotted

separately.

56 JENNIFER MOSES et (11.

There were no significant changes in body weight or percentage body fat over the course of the programme.

Psychological responses

Prelpost-training measures. There were no significant differences before training between groups on any of the POMS, coping or self-efficacy measures. Repeated measures analysis of variance identified a significant group by time interaction for ratings on the tension/anxiety scale of the POMS [F(3,71) = 2.94, p < O.OS]. This effect is summarised in Fig. 3. It is evident that reductions in tension/anxiety were reported only by subjects in the moderate exercise condition. This pattern was confirmed by breakdown contrast analyses, where the decrease in tension/anxiety shown by the moderate exercise group was significantly different from that seen in all other conditions; the latter did not differ from each other. It would appear, therefore, that beneficial effects in terms of tension/anxiety were only seen with moderate exercise.

TENSION - .90 ;

.85 --

.70 i

ANXIETY

0 WclHlng List

.65/ Pra Pod

TIME

FIG. 3.-Mean log transformed tension-anxiety score on the POMS for the four experimental condition\ before and after training.

No significant differences between groups or over time were apparent in the analyses of depression/dejection, anger/hostility, vigour/activity, fatigue/inertia or perceived self-efficacy. However, differences over time [F(1,71) = 3.70, p < 0.061 and group by time [F(3,71) = 2.61, p < 0.061 were present on the confusion scale. The pattern here was similar to that found in tension/anxiety, with greater decreases being seen in the moderate exercise group (mean change - 0.193) than in the high exercise (-0.039), attention-placebo (-0.0003) or waiting list (+0.008) conditions.

No significant effects were found on the perceived coping scales, but the group by time interaction was significant on the physical well-being scale [F(3,71) = 3.82,

Effects of exercise on mental well-being 57

p < 0.011. All three active treatment groups showed improvements on this measure from before to after training, while ratings decreased in the waiting list group. The largest change was observed in the attention-placebo condition (+0.146), with more modest increases in the high exercise (+0.046) and moderate exercise (+ 0.046) conditions.

Follow-up measures. Analysis of follow-up data was confined to three groups and to subjects who completed assessments both at pre-training and at 3 months post- training. A number of interesting effects were observed including a significant group by time interaction on the coping deficits scale, F(2,55) = 3.45, p < 0.05. As can be seen in Fig. 4, decreases in perceived coping deficits were reported in the moderate exercise group, but not in the high exercise or attention-placebo conditions, duplicating the pattern present immediately post-training in tension/ anxiety and confusion. A similar trend was presented on ratings of depression/ dejection, F(2,55) = 3.00, p < 0.061. Finally, the group by time interaction approached significance for the perceived coping assets scale [F(2,55) = 2.56, p < 0.081 where again it appeared that positive changes were confined to subjects in the moderate exercise condition.

,951

.90 1

.75

I

COPING DEFICITS

0 High exercise

. Moderate exercise

. Attention-Placebo

.70 -

PW 3 m f/up TIME

FIG. 4.-Mean log transformed perceived coping deficits for the three active conditions before training and at 3 months follow-up

DISCUSSION

This study was designed to asess the psychological effects of exercise training in sedentary but healthy adults from an inner city population. Typically, studies in this field have been conducted with campus-based U.S. college students. Our observations may therefore be more relevant than those in previous literature for identifying responses to exercise training in urban communities. Analysis of the

58 JENNIFER MOSES rt al

reasons people gave for wanting to take part in the project indicated that wishing to improve health (94.7%). lose weight (73.7%) and relieve stress (50%). were the commonest motives. The large proportion of participants wishing to lose weight may reflect the predominance of women in the sample. The number of women taking part was in line with the ratio of women to men responding to the initial advertisement and may be a product of the cultural expectations of health and fitness programmes.

A major concern was to develop a control condition that would match exercise training as closely as possible in terms of group structure. practice schedule and expectations concerning outcomes. The fact that people progressed through the attention-placebo programme to more ‘demanding’ levels over the weeks of training was an important component, since this allowed subjects in all conditions to experience a sense of achievement at attaining intermediate goals. The ratio of group to individual training was similar in all conditions, allowing group cohesion to develop to the same extent. Expectations remained well matched throughout the study.

It had been anticipated that more drop-outs might occur in the moderate exercise condition due to difficulties in managing the programme and restricting people to exercise within prescribed limits. This was the reason why waiting list subjects were allocated to the moderate exercise condition following the initial phase of the study. Assessments of aerobic capacity on the 12 min test (Fig. 2) indicated that very similar responses were produced by subjects in the original moderate exercise condition. and by waiting list subjects who completed training. In fact, adherence was similar in all conditions, averaging 80% between pre- and post-training (94 vs 75). This level compares favourably with results published in the literature [35]: indeed, it has been argued that HGG’%, is the maximum adherence rate to be expected for structured exercise programmes, even in populations with good facilities and favourable attitudes to exercise [36].

The analyses of diary records suggest that although only one session per week was supervised, subjects did practice on their own at a frequency only slightly below that requested. Overall, the average number of sessions was just over three per week instead of four. As might be expected. frequency of practice declined over the course of the study, though remaining at the level of three per week considered critical by the ACSM [30]. The exertion ratings indicate that different degrees of effort were made in the three conditions. with the highest levels in the high exercise group. The duration of sessions was differentiated in the high and moderate conditions as expected in weeks 1-5, but for the remaining weeks the sessions were longer than required in the moderate group. The reason for this is not known. Nor is it certain why the attention-placebo group reported longer sessions throughout. This may reflect their enjoyment of these undemanding mobility and flexibility exercises, and their determination to carry out the exercises slowly.

We observed changes in aerobic fitness that matched the activity levels of the different experimental groups in the results of the 12 min walk-run test. Although this test correlates well with maximal tests in mixed populations of the type studied here [37], it is a less reliable measure of fitness than estimates based on laboratory ergometry or maximal tests. Moreover, the 12 min test was not carried out by the waiting list group, so changes in this condition were not documented.* The result

Effects of exercise on mental well-being 59

should therefore be treated with caution. It is probable that the pattern of responses on the 12 min test are products, at least in part, of specific rather than generalised changes in aerobic fitness. Subjects in the high and moderate exercise conditions followed a walk/jog training schedule, and these were the activities assessed with the 12 min test. It is a well-established principle of training that practice with a particular set of muscles will lead to specific improvements in efficiency [38, 391. The result is unlikely to have been a motivational effect. since the three training groups had similar positive beliefs concerning their programmes, and the exertion ratings following the 12 min test runs did not differ.

The most interesting result to emerge from this study is that positive psychological responses were reported by subjects in the moderate exercise condition. but not those in the high exercise or attention-placebo conditions. This effect was apparent in tension/anxiety (Fig. 3) and confusion at post-training, and in perceived coping deficits at follow-up (Fig. 4), with trends in coping assets and depression/dejection. It was not therefore confined to a single outcome meausre,

but was observed in a number of ratings of mood and perceived coping ability. This result is theoretically important, since it contradicts the hypothesis that improve- ments in psychological state would be associated with aerobic conditioning. If this were the case, the high rather than moderate exercise group would have responded. The first hypothesis was also disconfirmed, in that psychological benefits were not observed in the attention-placebo condition. It appears. therefore, that psychological responses to exercise training are not due to expectancies or other features inherent in structured activity, but only emerge when an aerobic component is also present.

The explanation for the superiority of the moderate condition in comparison with the high exercise programme is not clear. It is possible that participants in the high exercise condition found the training too demanding, and that the rigour of the schedule mitigated against any improvements in well-being. The moderate exercise condition may have been more enjoyable, permitting subjects to achieve goals of physical activity that had previously seemed beyond them, without exerting undue effort. A more positive feeling of self-control may have been engendered, with less experience of distressing bodily sensations. The result is consistent with the second hypothesis outlined in the Introduction, in showing that vigorous physical activity is more important than improvement in aerobic fitness. Other data from human and animal research and from epidemiological surveys supports this conclusion. For example, Doyne and co-workers [40] observed reductions in depression in women participating in both aerobic and anaerobic training, even though objective improvements in fitness were not recorded. Mills and Ward [41] have shown that the development of stress-induced hypertension is attenuated in rats following exercise training, but that the effect is independent of physical conditioning. Epidemiologically, the links between exercise and cardiovascular mortality suggest a protective effect of vigorous activity [19-21, 421, and it is not certain that aerobic

*It had been hoped to use data from a post-training ergometer test in order to compute changes in fitness. However, data from the post-training session were not sufficiently reliable. owing to difficulties with the measure of oxygen extraction. These results are therefore excluded from this paper.

60 JENNIFER MOSES et al.

fitness needs to be achieved, although the data are inconsistent [43]. If the psychological responses observed in the present study are shown to be robust on replication, they may have important implications for the ways in which training programmes should be devised for the general public.

Acknowlecigements-This project was supported by the Health Promotion Research Trust, U.K. The authors are grateful to Eirean James for her assistance in data collection and processing.

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