Abstract
Regular exercise fosters fitness-enhancing benefits. We assume that exercise interventions become successful and sustainable if physiological benefits of exercise are also subjectively perceivable. The goal of this study was to examine how young inactive adults physiologically respond to an exercise intervention and how those responses are subjectively experienced. Furthermore, we aimed to assess whether the sequence of two distinct endurance-based exercise modes has an impact on physiological and subjectively experienced physical fitness. Thirty-one young inactive adults were assessed for this substudy of the larger iReAct study. Participants were randomly assigned to a high-intensity interval training (HIIT) or a moderate-intensity continuous training (MICT) group for 6 weeks and subsequently switched groups for a second training period. Physiological fitness data was collected at baseline, follow-up I, and follow-up II using a graded cardiopulmonary exercise test. Subjectively reconstructed (i.e., retrospective constructions) experiences relating to physical fitness were assessed at follow-up II using a biographical mapping method. A repeated-measures one-way ANOVA on each training group was performed to see whether physiological and subjectively experienced fitness differed across training periods. The rate of change between all variables was calculated for the first and the second training period in order to compare the agreement between physiological and subjective fitness improvements. Participants increased their fitness across the intervention period both physiologically and subjectively. However, the rate of change depended on the sequence of the two training modes. While VO2max increased significantly in both training periods in the MICT-HIIT sequence, a significant increase in VO2max in the HIIT-MICT sequence was only observed in the HIIT period. Participants similarly perceived those increases subjectively in their exercise-related physical fitness, although they experienced a significant decrease in the second period of the HIIT-MICT sequence. For subjectively perceived physical fitness relating to everyday activities, significant increases were only observed for the first period of the MICT-HIIT sequence. Young inactive adults can improve both their physiological and their subjectively perceived fitness through regular exercise. However, exercise modes and their sequence can make a substantial difference regarding measured and perceived physical fitness. Additionally, despite a favorable tendency toward HIIT over MICT, inter- and intra-individual variability, particularly in the subjective experiences of fitness, reiterates the necessity of individualized approaches to exercise.
Highlights
Researchers have described exercise as a “polypill” acknowledging its positive impact on biopsychosocial health and the decisive role it has come to play in both prevention and therapy (Fiuza-Luces et al, 2013; Rebelo-Marques et al, 2018)
Pairwise post-hoc analyses showed a significant difference from baseline to follow-up I in the HIITMICT group after high-intensity interval training (HIIT) (+ 16.0 ± 7.3%, p < 0.001), but no significant differences were found from follow-up I to followup II
Our analyses have shown that VO2max and perceived exerciserelated physical fitness significantly improved both in the HIITMICT and the MICT-HIIT group indicating that inactive young adults can physiologically and subjectively benefit from a structured exercise intervention
Summary
Researchers have described exercise as a “polypill” acknowledging its positive impact on biopsychosocial health and the decisive role it has come to play in both prevention and therapy (Fiuza-Luces et al, 2013; Rebelo-Marques et al, 2018). While dose-response-effects of exercise on health and fitness are well-established on a physiological level (Maturana et al, 2020), it is less clear whether and to which extent individuals who exercise subjectively experience those changes in their physical fitness over time. One reason might be a lack of knowledge about how physiological training effects of exercise correlate with the subjective experience of exercise. While several studies that assessed the relationship between actual (i.e., “objectively” measured) and perceived (i.e., self-reported) physical fitness report significant correlations for cardiorespiratory fitness measures and selfperceptions of endurance and fitness (Germain and Hausenblas, 2006; Monroe et al, 2010), there are no studies that examine how physiological adaptations to an exercise intervention relate to subjective perceptions of these adaptations over time
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
