Klaus Boes

Characteristics of the activity-affect association in inactive people: an ambulatory assessment study in daily life.

Acute and regular exercise as well as physical activity (PA) is related to well-being and positive affect. Recent studies have shown that even daily, unstructured physical activities increase positive affect. However, the attempt to achieve adherence to PA or exercise in inactive people through public health interventions has often been unsuccessful. Most studies analyzing the activity-affect association in daily life, did not report participants’ habitual activity behavior. Thus, samples included active and inactive people, but they did not necessarily exhibit the same affective reactions to PA in daily life. Therefore the present study investigated whether the association between PA and subsequent affective state in daily life can also be observed in inactive individuals. We conducted a pilot study with 29 inactive university students (mean age 21.3u2009±u20091.7u2009years) using the method of ambulatory assessment. Affect was assessed via electronic diary and PA was measured with accelerometers. Participants had to rate affect every 2u2009h on a six item bipolar scale reflecting the three basic mood dimensions energetic arousal, valence, and calmness. We calculated activity intensity level [mean Metabolic Equivalent (MET) value] and the amount of time spent in light activity over the last 15u2009min before every diary prompt and conducted within-subject correlations. We did not find significant associations between activity intensity and the three mood dimensions. Due to the high variability in within-subject correlations we conclude that not all inactive people show the same affective reactions to PA in daily life. Analyzing the PA-affect association of inactive people was difficult due to little variance and distribution of the assessed variables. Interactive assessment and randomized controlled trials might help solving these problems. Future studies should examine characteristics of affective responses of inactive people to PA in daily life. General assumptions considering the relation between affect and PA might not be suitable for this target group.

Does a 20-week aerobic exercise training programme increase our capabilities to buffer real-life stressors? A randomized, controlled trial using ambulatory assessment.

PurposeThe cross-stressor adaptation hypothesis suggests that regular exercise leads to adaptations in the stress response systems that induce decreased physiological responses to psychological stressors. Even though an exercise intervention to buffer the detrimental effects of psychological stressors on health might be of utmost importance, empirical evidence is mixed. This may be explained by the use of cross-sectional designs and non-personally relevant stressors. Using a randomized controlled trial, we hypothesized that a 20-week aerobic exercise training does reduce physiological stress responses to psychological real-life stressors in sedentary students.MethodsSixty-one students were randomized to either a control group or an exercise training group. The academic examination period (end of the semester) served as a real-life stressor. We used ambulatory assessment methods to assess physiological stress reactivity of the autonomic nervous system (heart rate variability: LF/HF, RMSSD), physical activity and perceived stress during 2xa0days of everyday life and multilevel models for data analyses. Aerobic capacity (VO2max) was assessed pre- and post-intervention via cardiopulmonary exercise testing to analyze the effectiveness of the intervention.ResultsDuring real-life stressors, the exercise training group showed significantly reduced LF/HF (βxa0=xa0−0.15, txa0=xa0−2.59, pxa0=xa0.01) and increased RMSSD (βxa0=xa00.15, txa0=xa02.34, pxa0=xa0.02) compared to the control group.ConclusionsUsing a randomized controlled trial and a real-life stressor, we could show that exercise appears to be a useful preventive strategy to buffer the effects of stress on the autonomic nervous system, which might result into detrimental health outcomes.