The Effect of Short-Term (10- and 15-min) Running at Self-Selected Intensity on Mood Alteration

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1 Journal of PHYSIOLOGICAL ANTHROPOLOGY and Applied Human Science The Effect of Short-Term (10- and 15-min) Running at Self-Selected Intensity on Mood Alteration Teru Nabetani 1) and Mikio Tokunaga 2) 1) Graduate School of Human-Environment Studies, Kyushu University 2) Institute of Health Science, Kyushu University Abstract The primary purpose of this study was to contrast the effects of two short-duration exercises on mood changes. A secondary goal was to examine the relationship between pre-exercise and post-exercise mood states. The subjects were 15 healthy male graduate students. They were involved in a within-subject design in which each individual completed two trials of running on a treadmill, one trial for 10 minutes and the other for 15 minutes. The Mood Checklist Short-form 1 (MCL-S1) used in the present study represents the participants mood states before, during, and after exercise. This questionnaire has three sub-scales measuring (a) pleasantness, (b) relaxation, and (c) anxiety. Participants ran on a treadmill for the assigned time at a self-selected intensity after being told to run at a rate that felt good and was not painful. ANOVA results showed that both of the short bouts of exercise affected the subjects mood, because the main effect of time spent exercising was observed in all sub-scales of the MCL-S1 and there were no significant differences in trial-by-time interaction. In addition to these results, there was a significant correlation between the two trial lengths in the amount of pleasantness and the amount of anxiety felt at post-exercise. There were moderate differences in the effect size (ES) for pre- and post-exercise pleasantness and anxiety levels. These results revealed similar patterns of change. It seems reasonable to conclude, based on this study, that exercise between 10 and 15 minutes results in similar psychological benefits for the person exercising. J Physiol Anthropol 20 (4): , Keywords: short-bout exercise, duration time, preexercise mood, treadmill Introduction The promotion of exercise behavior has been identified as a key component of obtaining a better quality of life. However, the lack of time has been proposed as the main reason why individuals drop out of exercise programs (Weinberg and Gould, 1999). Recently, researchers in exercise physiology and clinical physiology have indicated that an important factor is the total volume of exercise that is undertaken throughout the day (Pate et al., 1995; ACSM, 1998). Therefore, from a fitness and health professional s perspective, it would seem important to determine the minimum exercise duration needed to acquire exercise-related benefits. Although the effect of exercise participation on psychological health has received extensive attention, the effects of specific exercise durations on psychological health have not been fully examined. In psychological health, to improve mood states has two procedures that decreased negative mood states and increased positive mood states. Within the broad category of negative affect, anxiety may be the most widely investigated psychological state in the exercise domain. Although many studies have assessed affective response to exercise duration time, most of these studies investigated the response to be more than 20 min of exercise (Berger and Owen, 1988; Berger and Owen,1998; Garvin et al., 1997; Kennedy and Newton, 1997; Petruzzello and Tate,1997; Roth, 1989). Petteruzzulo et al. (1991) reviewed the effect of exercise on anxiety and concluded that although it appears that exercise durations longer than 20 min are most effective for reducing anxiety, further systematic research is required for bouts lasting less than 20 min. In studying anxiety, Thayer (1987) and Steptoe and Cox (1988) have reported the effects of short-bout exercise that is 10 min and 8 min, respectively. However, these studies did not settings different condition of time duration. Thus these studies lacked the appropriate

2 234 Short-Term Running and Mood Alteration experimental design for comparing the effect of time duration on mood. Furthermore, research on positive affect often fails to grasp the psychological effect of exercise duration. To our knowledge, there has been little attention in examining the effect of short bouts of exercise on mood alteration. O Connor et al. (1995) and Rejeski et al. (1995) suggested that the psychological benefits accrued from acute physical activity are influenced by pre-exercise levels of the psychological parameters under investigation. However, it is unclear whether this was true for exercise lasting less than 20 minutes. Given that recent health recommendations have advocated brief exercise, in our present study, exercise trials are set at a minimum of 10 min as shorter exercise bouts and 15 min compared to less than 20 min which is thought as beneficial exercise. In this study we explored (1) the effects of two shortterm exercise durations (10 and 15 min) on mood changes, and (2) the relationship between pre-exercise and post-exercise and mood states. Methods Participants The study participants were 15 healthy male graduate school students whose mean age (± SD) was 23.4 (± 1.5) years and whose body mass index (BMI) was 22.2 (± 2.5). Participants were neither sedentary individuals nor trained athletes. They participated in a within-subject design in which each individual completed two trials, one 10-min run and one 15-min run on a treadmill at random. All participants gave written informed consent and reported that they were in good health. Measurement We used the Mood Check List-Short form 1 (MCL-S1) (Hashimoto and Tokunaga, 1996) to evaluate each participant s mood states before, during, and after exercise. This questionnaire consists of 12 items using sub-scales to assess levels of pleasantness, relaxation, and anxiety. The main question asked, How do you feel right now? and each mood response option is accompanied by a 7-point scale ranging from 1 Very much so to 7 Not at all. Scoring the MCL-S1 consists of adding the points; a high score on the pleasantness and relaxation scales indicates a positive mood, whereas a high score in anxiety represents a negative mood. The MCL-S1 has been reported to have internal consistency reliabilities, with α=.903 for pleasantness, α=.913 for relaxation, and α=.765 for anxiety (Hashimoto and Tokunaga, 1996). In this study, to examine the internal consistency of the sub-scales of the MCL-S1, Cronbach alpha coefficients were calculated for the 10-min trial and 15-min trial assessment. The results indicated that each dimension appeared to possess adequate internal consistency, as the range of coefficients for pleasantness, relaxation, and anxiety were α= , α= , and α= in the measured time course (pre-exercise, 6 min, 10 min, and post-exercise), respectively. Procedure Participants were initially given a brief description of the study and an outline of their expected involvement. They were prepared for the exercise with the application of three disposable pre-gelled surface electrodes with a modified bipolar lead in the V5 position. ECG was monitored continuously during exercise by a telemeter unit (FUKUDA DENSHI/DS-882), and heart rate (HR) was recorded every minute. Immediately prior to exercise, participants completed the MCL-S1. Then the participants ran on a treadmill (WOODWAY; ELG-2) for the assigned time at a self-selected intensity, which was whatever level of exercise felt good and was not painful. Typically, researchers examining the impact of acute exercise on psychological benefits employ a relatively objective measure of exercise intensity, such as percentages of estimated maximal oxygen uptake (%VO2max) and maximal heart rate (%HRmax )( Petruzzello et al., 1991). Although these procedures ensure that exercise intensity is equivalent across participants, it is difficult to monitor whether the majority of exercisers work out at an accurately measured exercise intensity without the aid of laboratory equipment. These physiological parameters are not necessarily an indication of optimal mood state in each individual exerciser. To enhance the probability that exercise may be perceived as enjoyable, the treatment involved a focus on self-selected exercise intensity. Thus, we allowed participants to opt for self-select intensity. The time course is presented in Fig. 1. In the first 5 min of each exercise trial, the participant had to choose an exercise intensity (i.e., the treadmill speed) that would be followed for the rest of the trial. The MCL-S1 was assessed at the 6-min and 10-min mark during the exercise trial. Subjects were asked questionnaire items by the experimenter during the exercise trial, and the subjects answered each item. After completion of each trial the MCL-S1 was readministered within 2 min. Therefore, the measurement of post-exercise was completed at 12 min (10-min trial), and 17 min (15-min trial). Taking a within-subject design, the two trials were carried out on another day in the present study. Statistical analysis In the present study, the analytical plan involved two distinct phases. Initially, to determine mood changes between before, during, and after exercise, MCL-S1 data were analyzed using a two-factor (trial and time) analysis

3 Nabetani, T et al. 235 Fig. 1. The time course for the experiment, in which the upper line indicates the 15-min trial and the lower line indicates the 10-min trial. Thick lines indicate during running and broken lines mean in recover. of variance (2-way ANOVA) with the Greenhouse-Geisser modification, giving the result based on Mauchly s test of sphericity. Statistical significance was set at p<0.05. Then, when appropriate, a Scheffe s multiple comparison was used post-hoc test. Corrected effect size (ES) was used in this paper to remove positively biased small samples. A virtually biased estimate of ES can be modified by multiplying the ES by the correction coefficient that Hedges (1981) demonstrated. The second phase of analysis used Pearson s correlation analysis to determine whether affective state at pre-exercise associated with affective response at post-exercise for pleasantness, relaxation, and anxiety. SPSS 10.0J for Windows was used to analyze the data for this study. Results Treadmill Running speed was ± 21.6 m/min in the 10-min trial and ± 14.7 m/min in the 15-min trial. HR at the end of exercise was ± 13.8 bpm in the 10-min trial and ± 13.4 bpm in the 15-min trial. The workload of these trials were estimated at about 80%HRmax. From this viewpoint, these workloads were lower than previous research (Hashimoto et al., 1991) that used to opt for self-selected intensity. The paired t- test for the intensity and HR showed no significant difference between the two trials. In other words, the two trials did not reflect significantly different intensities of exercise. Affective response Fig. 2 shows the MCL-S1 sub-scale ratings before, during, and after exercise for the two trials. An analysis of variance (2 trials 4 times) with repeated measures on the time factor was calculated to examine each sub-scale of MCL-S1 response to exercise. The results for ANOVA are presented in Table 1. Pleasantness: The results indicated the main effect for the trial (F (1,14)=4.80, p=.05 and time F (1.73, 24.29)=7.65, p=.01). However, there was no interaction for the trial-by-time. Although a post-hoc test showed no significant difference in the experience of pleasantness in the 10-min trial, there are significant differences in the 15-min trial between pre-exercise and post-exercise (p<.01), between the 6-min mark and post-exercise (p<.01), and between the 10-min mark and post-exercise (p=.01). Because of the relatively small sample size, within-trial ESs for pleasantness were calculated. The ESs were.86 (10-min test) and.62 (15-min test).

4 236 Short-Term Running and Mood Alteration The ES for changes in relaxation was.33 for the 10-min trial and.07 for the 15-min trial. Anxiety: The results indicated main effects for trial (F (1,14)=4.65, p=.05) and time (F (1.56, 21.77)=6.60, p=.01), whereas trial-by-time interaction was not significant. Post-hoc tests revealed a significant difference from pre-exercise to 10 min (p=.03) and from pre-exercise to post-exercise (p=.02) in the 10-min trial, and there are significant differences from pre-exercise to 6 min (p=.04), from pre-exercise to 10 min (p=.01), and from pre-exercise to post-exercise (p<.01) in the 15-min trial. The ES for changes in anxiety were.61 for the 10- min trial and.51 for the 15-min trial. From a statistical viewpoint, at least, the results suggested that mood states were influenced by exercise. In the categories of pleasantness and anxiety, the differences of pre- and postexercise were of a moderate ES. Relationship between two trials at post-exercise: Correlation coefficients were calculated to determine the relationship between the 10-min trial and the 15-min trial at pre-exercise and post-exercise for the three MCL-S1 sub-scales, pleasantness, relaxation, and anxiety. Table 2 shows the correlation coefficients for the three sub-scales at post-exercise. There are significant correlations in the pleasantness scale and the anxiety scale. In other words, there was a similarity between the 10-min trial and 15- min trial in mood states at post-exercise. Fig. 2. Changes of mood in short-bout running in relation to time course. These graphs indicate the sub-scales for pleasantness, relaxation, and anxiety at the top, middle, and bottom, respectively. In pleasantness and relaxation scales, high score means positive mood states. On the other hand, high score means negative mood states in anxiety scale. Each figures on the error bar indicated the ES (effect size). Data are presented as average value ± SD min, min. Relaxation: The results indicated no main effect for trial and trial-by-time interaction. However, there was a main effect for time (F (1.89, 26.44)=4.34, p=.03). A posthoc test showed that there were no significant differences in the 10- and 15-min trail trials about time factor, respectively. The ES was calculated within each trial. Effect of pre-exercise mood states Correlation analyses were executed to examine the effect of pre-exercise mood states on the amount of mood change. Table 3 shows the correlation coefficients for the between change of mood state (post-exercise minus preexercise) and the pre-exercise mood state in each trial. Results indicated that in the 15-min trial, there are significant negative correlations in the pleasantness scale and anxiety scale, and in the 10-min trial there are significant negative correlations in the anxiety scale only. When the data for the two trials are considered together, there are significant negative correlations in the pleasantness score and the anxiety score. These negative correlations in the present study suggest that the mood changes are influenced by preexercise level. The results indicate that the lower the mood state when pre-exercise begins, the greater the improvement of mood by post-exercise. Discussion The primary purpose of this study was to examine whether short bouts of exercise, up to 15 min long, had measurable psychological benefits. We found that both 10- and 15-min bouts of exercise affected mood, as shown by the fact that all sub-scales of the MCL-S1 exhibited a main effect for time and there was no interaction for trial-

5 Nabetani, T et al. 237 Table 1 Results of ANOVA about sub-scales of MCL-S1 pleasantness relaxation anxiety trial effect F=4.80* F=4.65* time effect interaction F=7.65** F=4.34* F=6.60** post-hoc 10-min trial15-min trial 10-min trial15-min trial 10-min trial15-min trial pre vs 6 min * pre vs 10 min * ** pre vs post ** * ** 6 min vs 10 min 6 min vs post ** 10 min vs post ** **: P<.01, *: P<.05. Table 2 Correlation coefficients between 10- and 15-min trial at post-exercise r pleasantness 0.69 ** relaxation 0.40 anxiety 0.63 ** **: P<.01. Table 3 Correlation coefficients for between change of mood state and pre-exercise score in 10-min and 15- min trial 10-min 15-min total Pleasantness ** 0.59** Relaxation Anxiety 0.77** 0.85** 0.80** **: P<.01. by-time. The ES for the increase in pleasantness in this study was.62 in the 10-min trial and.86 in the 15-min trial. The ES for changes in relaxation was.33 for the 10- min trial and.07 for the 15-min trial, and the ES for changes in anxiety was.61 for the 10-min trial and.51 for the 15-min trial. Although these findings cannot be compared easily with other studies, in the behavioral science, ESs equal to.20,.50, and.80 represented small, medium, and large differences, respectively (Thomas and Nelson, 1996). From this point of view, at least, in pleasantness and anxiety, the ESs on pre-post exercise difference were moderate in both trials. We should note especially that the ES for the increase in pleasantness was.86 in the 15-min trial. In addition to these findings, correlation coefficients for the pleasantness scale and anxiety scale were significant in post-exercise. Judging from the above, it seems that there are similar effects of the 10-min trial and the 15-min trial in the pattern of changes in the pleasantness scale and anxiety scale. As with the traditional assumptions regarding the effects of exercise intensity, the long-held belief regarding the role of the duration of the exercise bouts has been that it must exceed a relatively demanding threshold in order for the exercise bouts to produce significant affective benefits. A review by Petruzzello et al. (1991) revealed by meta-analysis that exercise lasting 0 to 20 min (ES=.04) resulted in significantly lower effect sizes than did exercise lasting 21 to 30 min (ES=.41) in anxiety. This result suggested that exercise needs to occur for at least 20 min to produce anxiety-reducing effects. However, in this study, the ES in the anxiety scale was.61 in the 10-min trial and.51 in the 15-min trial, which establishes that short-bout exercise can have an anxiolytic effect. Steptoe and Cox (1988) reported that high-intensity exercise led to increases in tension, anxiety, and fatigue, whereas positive mood (vigor and exhilaration) changes were seen following low-intensity exercise only. Moreover, Rudolph and Butki (1998) compared the effects of treadmill running with ratings of perceived exertion (RPE) of 13 ( somewhat hard ) for 10, 15, and 20 min, using the Subjective Exercise Experiences Scale (SEES) and self-efficacy. Their study results indicate that 10 min of aerobic exercise is sufficient to increase selfefficacy and to enhance positive well-being in moderately active individuals, which seems to refute the assumption of a threshold duration required for exercise-associated affective changes to occur. The present results agree with those obtained by Rudolph and Butki (1998) and are good evidence that short bouts of exercise might be effective for mood alteration. The present study also showed that mood alteration has a tendency to change gradually with time course. As observed in Fig. 2, the assumption of threshold duration becomes more open to question. In this study, there is not critical point, but mood alteration is gradually during exercise. The secondary purpose of the present study was to examine the relationship between pre-exercise and post-

6 238 Short-Term Running and Mood Alteration exercise in mood states. Because the results indicated there was a significant negative correlation between preexercise mood states and the amount of mood change (post-exercise minus pre-exercise), the results in the present study support previous research (O Connor et al., 1995; Rejeski et al., 1995) that the psychological benefit accrued from acute physical activity, such as an exercise of 10-min and 15-min duration, is influenced by preexercise levels. Blumenthal et al. (1988) observed that only clinically depressed patients experienced a decrease in depression after exercise training. Furthermore, Lennox et al. (1990) reported that exercise training had no impact on the moods of individuals selected from a non-clinical population. These findings suggest that individuals with lower average mood states are likely to improve their mood more after exercise than are individuals with higher average mood states. In the present study, the results also suggested that the psychological benefit accrued from acute physical activity are influenced by pre-exercise level. One limitation of this study was the lack of a placebo control group. Therefore, we cannot be sure that a placebo effect did not influence the outcome of the study. In replications of this work it would be wise to include a placebo control. A second limitation of this study was the choice of a psychological measurement tool. Since this measurement tool was developed in Japan, its reliability and validity have not been proven in other countries. Thus, it provides no justification for international adaptation; however, it seems reasonable to suppose that this measurement tool is appropriate for making conclusions about a Japanese study population. In addition, it needs further consideration regarding the relationship between physiological response, such as HR during exercise trial, and mood alteration. We may leave the details to further study. We conclude that mood states in pleasantness and anxiety were improved by short bouts of exercise such as 10 min and 15 min. In addition to this, the psychological benefits of 10 min of exercise and 15 min of exercise appear to be similar. And it is also clear that mood changes were influenced by pre-exercise mood states in short-bout exercise. Since short bouts of exercise can be accumulated throughout the day to achieve health benefits, these findings indicate that this activity can play a critical role in adherence to an exercise regime. This information may contribute to establishing a healthy exercise routine that will improve people s quality of life. Summary Fifteen healthy male graduate school students participated in this study as subjects. The tasks were 10 min and 15 min of running on a treadmill with mood checks at pre-exercise, during exercise, and post-exercise. The results are summarized as follows: 1. There are main effects for time in the 10-min trial and 15-min trial. The ES levels were more than moderate in the pleasantness scale and the anxiety scale. 2. Results of correlation analysis suggested that there is a similarity between the 10-min trial and the 15-min trial in post-exercise mood states in the pleasantness scale and the relaxation scale. 3. There are significant negative correlations between pre-exercise mood state and difference scores of mood state (post-exercise score minus pre-exercise score). This indicates that the lower the mood state at preexercise, the more improved the mood state at postexercise. References American College of Sports Medicine (1998) The recommended quantity and quality of exercise for developing and maintaining cardiorespiratory and muscular fitness, and flexibility in healthy adults. Med Sci Sports Exerc 30: Berger BG, Owen DR (1988) Stress reduction and mood enhancement in four exercise modes: swimming, body conditioning, hatha yoga, and fencing. Research Q Exerc Sport 59: Berger BG, Owen DR (1998) Relation of low and moderate intensity exercise with acute mood change in college joggers. Percept Mot Skills 87: Blumenthal JA, Emery CF, Rejeski WJ (1988) The effect of exercise training on psychosocial functioning after myocardial infraction. J Cardiopulmonary Rehabil 8: Garvin AW, Koltyn KF, Morgan WP (1997) Influence of acute physical activity and relaxation on state anxiety and blood lactate in untrained college males. Int J Sports Med 18: Hashimoto K, Saito A, Tokunaga M, Isogai H, Takayanagi S (1991) The effect of stress reduction following exercise and sport activity (2): On mood change by acute self-paced jogging (in Japanese). J Health Sci 13: 1-7 Hashimoto K, Tokunaga M (1996) Reliability and validity of the mood check list-short form (MCL-S,1) measuring the mood state during exercise (in Japanese). J Health Sci 18: Hedges LV (1981) Distribution theory for Glass s estimator of effect size from a series of experiments. J Ed Statistics 6: Kennedy MM, Newton M (1997) Effect of exercise intensity on mood in step aerobics. J Sports Med Phys Fitness 37: Lennox SS, Bedell JR, Stone AA (1990) The effect of exercise on normal mood. J Psychosom Res 34:

7 Nabetani, T et al. 239 O Connor PJ, Pettruzzello SJ, Robinson TL (1995) Anxiety response to maximal exercise testing. Br J of Sports Med 29: Pate RR, Pratt M, Blair SN, Haskell WL, Macera CA, Bouchard C, Buchner D, Ettinger W, Heath GW, King AC, Kriska A, Leon AS, Marcus BH, Morris J, Paffenbarger Jr. RS, Patrick K, Pollock ML, Rippe JM, Sallis J, Wilmore JH (1995) Physical activity and public health: A recommendation from the Centers for Disease Control and Prevention and the American College of Sports Medicine. JAMA 273: Petruzzello SJ, Landers DM, Hatfield BD, Kubitz KA, Salazar W (1991) A meta-analysis on the anxietyreducing effects of acute and chronic exercise: Outcomes and mechanisms. Sports Med 11: Petruzzello SJ, Tate AK (1997) Brain activation, affect, and aerobic exercise: An examination of both stateindependent and state-dependent relationships. Psychophysiology 34: Rejeski WJ, Gauvin L, Hobson, ML, Norris JL (1995) Effect of baseline responses, in-task feelings, and duration of activity on exercise-induced feeling states in women. Health Psychol 14: Roth DL (1989) Acute emotional and psychophysiological effects of aerobic exercise. Psychophysiology 26: Rudolph DL, Butki BD (1998) Self-efficacy and affective responses to short bouts of exercise. Journal of Applied Sport Psychol 10: Steptoe A, Cox S (1988) Acute effects of aerobic exercise on mood. Health Psychology 7: Thayer RE (1987) Energy, tiredness, and tension effects of a sugar snack versus moderate exercise. J Pers Soc Psychol 52: Thomas JR, Nelson JK (1996) Becoming acquainted with statistical concept. In Research methods in physical activity. Champaign, IL: Human Kinetics, Weinberg RS, Gould D (1999) Exercise behavior and adherence. In Foundation of sport and exercise psychology. 2nd ed. Champaign, IL: Human Kinetics, Received: October 18, 2000 Accepted: May 7, 2001 Correspondence to: Teru Nabetani, 6-1 Kasuga Park, Kasuga City, Fukuoka , Japan terunabe@ihs.kyushu-u.ac.jp