PHYSICAL ACTIVITY DOSE FOR AFFECTIVE RESPONSE IN ACTIVE WOMEN WITH 5+ HOURS OF DAILY SEDENTARY TIME: A PILOT STUDY

Abstract

The majority of U.S. adults are not sufficiently active to reap health benefits. Affective response to physical activity may be a predictor of long-term adherence to an active lifestyle, with positive affect predicting greater physical activity participation than negative affect. While individual differences exist, the current belief is that moderate intensity activity (below the ventilatory threshold) is more likely to produce positive affect than vigorous intensity activity (at or above the ventilatory threshold). However, few studies assess affect beyond 60 minutes postexercise. Therefore, it is unknown how long exercise-induced affective improvements may be sustained, and whether duration of affective improvement is impacted by exercise dose. PURPOSE: The purpose of this study was to examine affective response following four different exercise conditions: 30 minute duration / high intensity, 30 minute duration / moderate intensity, 10 minute duration / high intensity, and 10 minute duration / moderate intensity, to determine which combination of intensity and duration is followed by the longest lasting improvement in affect among healthy females who meet 2008 physical activity guidelines, but are also sedentary at least 5 hours per day. METHODS: This study used a repeated measures, counter-balanced design in which every study participant completed four different exercise sessions on four different days and completed hard copy questionnaire assessments of affect before, during, and immediately after each exercise session, as well as online (mobile accessible) assessments of affect 1 hour, 3 hours, and 5 hours after exercise. Participants additionally completed affect assessments at corresponding timepoints to the exercise conditions, during two non-exercise control days. For exercise conditions, each participant was assigned a high intensity and moderate intensity heart rate range to stay within, based on individual maximum heart rate reserve (HRR). HHR was calculated using age-predicted maximum heart rate and devicemeasured resting heart rate (using Polar heart rate monitors). Affect was assessed using the Feeling Scale and the Subjective Exercise Experience Scale. RESULTS: Participants were six active females aged 23.7 [more-or-less] 3.1 years who met or exceeded the 2008 physical activity guidelines of the United States Department of Health and Human Services, but also accumulated at least 5 hours of sedentary time per day. A within-subjects repeated measures ANOVA was conducted to test the main effects of exercise condition and passage of time on Feeling Scale score, Positive Well-Being, Psychological Distress, and Fatigue. Results indicated a significant effect for Time (np² = .65, p = .006) on Feeling Scale score and a significant effect for both Time (np² = .46, p = .01) and Condition (np² = .41, p = .03) on Positive Well-Being. There were no significant effects for Time (np² = .16, p = .45) or Condition (np² = .23, p = .23,) on Fatigue and no significant effects for Time (np² = .24, p = .26) or Condition (np² = .08, p = .59) on Psychological Distress. Effect size calculations revealed large (d[greater-than or equal to].80) improvements in mean Feeling Scale score at every post-exercise timepoint (compared to baseline), following all exercise conditions except the 10 minute, moderate intensity condition. Although the repeated measures ANOVA showed no significant effects of exercise condition or passage of time on Psychological Distress, effect size calculations revealed large (d[greater-than or equal to].80) improvements in Psychological Distress following the 10 minute, high intensity exercise condition specifically. These improvements were apparent at every post-exercise timepoint. Improvements in Fatigue and Positive Well- Being following exercise were small to moderate. CONCLUSION: The results of this study indicate that improvements in affect may be sustained up to five hours. Effect size comparisons for mean change in affect following each exercise and control condition indicated that distinct affective states (Positive Well-Being, Psychological Distress, Fatigue) may be more sensitive to exercise dose than broadly measured affect (Feeling Scale). Additional research with a larger sample size and tight monitoring of control conditions is suggested.