Acute psychological benefits of aerobic exercise: A field study into the effects of exercise characteristics
Mária Rendi 1 1
Faculty of Phys. Ed. Sport Sci., Semmelweis University, Budapest, Hungary Attila Szabo 2, *
2
National Institute for Sport Talent Care and Sport Services, Budapest, Hungary Now at: Institute of Psychology, Eötvös Loránd University, Budapest, Hungary Tamás Szabó 2
2
National Institute for Sport Talent Care and Sport Services, Budapest, Hungary Attila Velenczei 2
2
National Institute for Sport Talent Care and Sport Services, Budapest, Hungary Árpád Kovács 2
2
National Institute for Sport Talent Care and Sport Services, Budapest, Hungary
* Correspondence: Dr. Attila Szabo (Ph.D.) E-mail:
[email protected] This is a pre-publication version of the finaal paper published in Psychology, Health & Medicine. Please cite this paper as:
Rendi, M., Szabo, A., Szabó, T., Velenczei, A., & Kovács, Á. (2008). Acute psychological benefits of aerobic exercise: A field study into the effects of exercise characteristics. Psychology, Health & Medicine, 13(2), 180-184.
2 Abstract Eighty volunteers were tested in their natural exercise environment consisting of a fitness centre they regularly attended. Half of the sample exercised on a stationary bicycle whereas the other half on a treadmill. All participants filled-in the Exercise Induced Feeling Inventory (EFI - Gauvin & Rejeski, 1993) before and after their 20 minutes of exercise that was performed at self-selected workload. The results revealed that exercise intensity and the other parallel measures like heart rate, perceived exercise intensity, and estimates of burned calories were higher in participants who ran in contrast to those who cycled. There were no differences in self-reports of enjoyment of the exercise sessions and in the psychological improvements from pre- to post-exercise between the groups. It is concluded that significant psychological improvements occur even after a 20-minute bout of exercise and these changes are independent of the workload or exercise intensity. Keywords: Aerobic exercise, Affect, Mood, Psychological well-being, Workload Introduction The acute psychological benefits of aerobic exercise are well established in the extant literature. Two unresolved issues revolve around the workload or intensity of exercise and modality or form of exercise. Some researchers found evidence in favour of high intensity exercise (Barabasz, 1991; Cox et l., 2006; Daley & Welch, 2003; Watanabe et al., 2001), yet others proposed that low or moderate intensities of exercise yield most psychological benefits (Bixby & Lockbaum, 2006; Plante & Rodin, 1990; Steptoe & Cox, 1988; Tate & Petruzzello, 1995). Nevertheless, a few scholars found no relationship between the exercise intensity and psychological gains (Parfitt et al., 2000; Szabo, 2003). The latter findings could be related to the preferred workload employed in those studies in which choice or preference (Ekkekakis et al., 2006) and the ensuing enjoyment (Motl et al., 2000; Zervas et at., 1993) are present in contrast to an experimenter imposed workload in studies setting the exercise intensity for the participants. Indeed, Szabo (2003) showed in both field and laboratory work that self-selected workloads in running/jogging yield substantial psychological benefits that are unrelated to the intensity (speed/time) of the run. While it is generally agreed that aerobic exercise generates the most psychological benefits, little research effort was invested in the comparing two or more forms of aerobic exercise. Snowball and Szabo (1998) found that ergometer cycling, rowing and treadmill running at a constant exercise workload yielded equal psychological benefits. However, at self-selected workloads the mode of exercise often also influences the intensity of exercise. For example, average walking, swimming, cycling, or running workloads may differ for the everyday exercisers under self-selected workload conditions. The aim of the current research was to determine the acute psychological effects of running and cycling at participant-selected workloads and to establish a posteriori whether the preferred workload is related to the magnitude of the expected positive psychological benefits of exercise. Measures and Procedure Eighty volunteers (mean age 35 years ± SD = 8.1 years) were recruited from among the regular users of a large urban fitness centre. Seventy-six participants were males and four were females.1 They were randomized into a cycling and a running group. The volunteers completed the Exercise-Induced Feeling Inventory (EFI - Gauvin & Rejeski, 1993) within five minutes before and after their 20-minute exercise, at self-selected workloads, on either a stationary cycle or a treadmill. All participants wore a “Polar Favor” heart rate monitor for
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3 subsequent determination of exercise heart rates and exercise intensity expressed in terms of percent of maximal heart rate. In addition, perceived exercise workload and enjoyment of the exercise session were measured with 7- and 5-point Likert scales. Finally, distance travelled and weight-corrected calories-burned were read directly from the display of the exercise equipments. All testing took place in the participants’ natural (fitness suite) exercise environment while the experimenters ensured that the participant does not engage in any form of interaction with others. Apart from convenience, it was conjectured that carrying out the study in the field would increase the external validity of the findings. Results Initially the exercise-relevant measures were compared between the running and the cycling group by using a multivariate analysis of variance (MANOVA). This test yielded a statistically significant multivariate main effect for exercise groups (Wilks’ Lambda = .034, F (6, 73) = 349.22, p < .0001). These results are further illustrated in Table 1. The effects sizes (Cohen’s d) were calculated where statistically significant differences were found between the two groups. The calories-burned, although weight-corrected, were considered as estimates only because of relatively imprecise nature of this reading on gym equipments.
Table 1: The table presents the means and standard deviations (SD) for the six exerciserelated measures for the running and cycling exercise groups along with the F-values, probability levels (p), and effect sizes (d).
Exercise-Relevant Measures
Exercise heart rate Exercise Intensity (Percent (%) of maximal heart rate) Distance completed (km) Calories burned (estimate only) Perceived exercise workload (max. 7) Perceived exercise enjoyment (max. 5)
Mean / SD Running (n = 40)
Mean / SD Cycling (n = 40)
F(1,78)
p
d
156.5 (13.6)
132.8 (16.5)
49.1
.001
1.57
83.6 (6.3)
73.0 (8.9)
37.7
.001
1.37
3.2 (0.9) 257.1 (51.4) 4.1 (1.0)
6.66 (1.1)
237.2
.001
3.41
162.0 (20.3)
118.0
.001
2.43
3.5 (1.)
7.2
.009
0.60
4.1 (0.7)
4.3 (0.6)
1.8
NS
-
* NS = not significant Psychological data obtained with the EFI were analysed with group (running, cycling) by period (pre-, post-exercise) mixed model repeated measures multivariate analysis of variance (RM-MANOVA). This test only yielded a period multivariate main effect (Wilks’ Lambda = .203, F (4, 76) = 74.6, p < .0001). Since no group main effect or interaction was revealed, the period main effect was followed up with univariate repeated measures analyses of variances to examine which of the four dependent measures contributed to the multivariate main effect. The results of these tests, along with the means, standard deviations (SD) and the calculated effect sizes (d), are illustrated in Table 2.
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4 Table 2: The table presents the means and standard deviations (SD) for the four dependent measures on the EFI derived before and after exercise (n = 80) and the F values from the univariate repeated measures analyses of variances testing the differences between the two (pre- and post-exercise) periods along with the probability levels (p), and effect sizes (d).
Psychological Measures (Subscales of the EFI)
Positive engagement Revitalization Tranquillity Physical exhaustion
Mean / SD Pre-exercise
Mean / SD Post-exercise
F(1,79)
p
d
8.5 (2.1) 6.8 (1.6) 7.5 (2.1) 4.4 (1.8)
10.3 (1.6) 8.8 (1.9) 9.3 (1.9) 6.9 (2.0)
92.2 93.3 66.7 64.5
.0001 .0001 .0001 .0001
0.86 1.27 0.89 1.22
Since statistically significant differences were found between the exercise intensity in running and cycling, and intensity was self-selected it is important to report the minimum and maximum values for the exercise heart rates. Accordingly, heart rates ranged from 128 beats per minute (bpm) to 182 bpm in running and from 102 bpm to 162 bpm in cycling. Fifty-one out of the 80 participants (64% of the sample) exercised at a heart rate between 128 bpm and 162 bpm representing the “common range” or the overlap between the minimum heart rate in running and the maximum heart rate in cycling. Statistical examination of the psychological data using 64% of the sample, representing those who exercised within the common range (cycling: n=25; running n=26), yielded identical results to those obtained with the 100% of the sample. To examine whether a relationship between the self-reported measures of the EFI and exercise intensity exists, difference scores were calculated by subtracting pre-exercise values from the post-exercise values. These difference scores were then correlated with the exercise intensity expressed as percent of maximal heart rate. Statistically no significant correlations were found for positive engagement, revitalization, and tranquillity. However, as expected a positive correlation was found between physical exhaustion and exercise intensity (r = .33, p < .003). Discussion and Conclusion Using an exercise specific psychological instrument, this field study shows that the form of the aerobic exercise does not mediate the acute psychological benefits derived from the exercise. In agreement with previous studies by Parfitt et al. (2000) and Szabo (2003), important affective benefits were noticed in all dependent measures. These changes were in the expected direction. For example, positive engagement, tranquillity, and revitalization all increased suggesting an immediate after-exercise “high” regardless whether the participants were running or cycling. Perceived physical exhaustion also increased, which was expected in light of the relatively high intensity exercise (73% and 83% of maximal heart rate reserve in cycling and running respectively). The strength of these findings is substantiated not only by the large effect sizes (refer to Table 2), but also by the fact that the results were obtained in a “natural” exercise environment, in which the participants normally work out, in contrast to the often artificial nature of a psychology laboratory. In addition to the modality of exercise, this study also shows that differences in the exercise intensities were not sufficient to produce measurable differences in psychological gains attained by the two groups. Cycling on the average was performed at lower intensity, that was justified by both physical and psychological measures (refer to Table 1), without resulting in lesser psychological benefits. Furthermore, the lack of correlation between the
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5 difference scores in the psychological variables, representing pre- to post-exercise changes, and exercise intensity also suggests that the latter is unrelated to the positive psychological benefits of acute aerobic exercise. Since the rating of enjoyment of exercise was nearly the same for the two groups, it appears that enjoyment (Zervas et al., 1993) may be important in deriving acute psychological benefits from the exercise. Assuming that freedom of choice in the selection of exercise intensity leads to greater enjoyment, which then could maximise psychological gains (Csikszentmihalyi, 1982), it is suggested that future studies examine the exercise-affect relationship in a theoretical perspective by resorting to participant-selected workloads rather than a forced exercise workload. The results of this research strongly suggest that neither the form nor the intensity of aerobic exercise impacts the acute psychological responses measured after a 20 min bout of workout in a naturalistic exercise environment. The take home message of this study appears to lend scholastic validity to the “just do it” slogan with respect to the immediate psychological benefits of exercise. Acknowledgement The authors are grateful to student L.Lynchehan for her assistance in data collection as well as the data reduction.
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6 Steptoe, A., & Cox, S. (1988). Acute effects of aerobic exercise on mood. Health Psychology, 7, 329-340. Tate, A.K., & Petruzzello, S.J. (1995). Varying the intensity of acute exercise: implications for changes in affect. Journal of Sports Medicine and Physical Fitness, 35, 295-302. Watanabe, E., Takeshima, N., Okada, A., & Inomata, K. (2001). Effects of increasing expenditure of energy during exercise on psychological well being in older adults. Perceptual and Motor Skills, 92, 288-298. Zervas, Y., Ekkekakis, P., Emmalnuel, C., Psychoudaki, M., & Kakkos, V. (1993). The acute effects of increasing levels of aerobic intensity on mood sates. Proceedings of the Eighth World Congress of Sport Psychology, (pp. 620-624). Lisbon: Portugal.
This is a pre-publication version of the finaal paper published in Psychology, Health & Medicine. Please cite this paper as:
Rendi, M., Szabo, A., Szabó, T., Velenczei, A., & Kovács, Á. (2008). Acute psychological benefits of aerobic exercise: A field study into the effects of exercise characteristics. Psychology, Health & Medicine, 13(2), 180-184.
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