Physiological and psychological responses to six weeks of high-intensity interval and moderate-intensity continuous training in physically inactive young adults
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Master of Science (MS) in Physical Education: Exercise Science
Wellness and Movement Sciences
High-intensity interval training (HIIT) has been proposed as a public health strategy to promote physical activity; yet, there is limited evidence examining factors related to adherence to HIIT.
PURPOSE: To determine the effect of six weeks of HIIT and moderate-intensity continuous training (MICT) on physiological and psychological responses to training.
METHODS: Physically inactive young adults (n = 20; age = 21.4 ± 2.2 years) were randomized to the HIIT or MICT group. Assessments of body composition, cardiorespiratory fitness (CRF), moderate-to-vigorous physical activity (MVPA) and sedentary behavior levels were completed prior to and following the intervention. Participants completed 18 training sessions overall, with the first half of the intervention supervised and the latter half unsupervised. Within-session psychological variables were measured pre-, mid-, and post-training at each session. Across-session psychological variables were measured at the end of the first, ninth, and eighteenth training sessions. Differences were analyzed using 2 (group) x 2 (time) ANCOVAs for physiological variables, 2 (group) x 6 (time) ANCOVAs for within-session psychological variables, and 2 (group) x 3 (time) ANOVAs for across-session psychological variables.
RESULTS: CRF (Δ = 2.8 ml·kg-1·min-1; p = 0.03) and peak power output (Δ = 20.2 watts; p = 0.01) improved across the intervention with no between group differences (p > 0.05). There were no main effects of time, group, or interaction for body composition, affect, in-task enjoyment, self-efficacy, MVPA, or sedentary behavior levels (p > 0.05 for all). Perceived competence increased from weeks one (4.7 ± 0.2) to three (5.4 ± 0.1; p = 0.01) with no differences at week six (5.2 ± 0.2; p > 0.05). There was no difference in post-exercise enjoyment from weeks one to three (p = 0.07), but it declined from weeks three to six (p = 0.003) with a significant time by group interaction (p = 0.02).
CONCLUSIONS: Over six weeks of training CRF improved comparably for HIIT and MICT; however, the overall time commitment for HIIT was substantially shorter. Further, the increase observed in perceived competence across supervised training suggests it may be important to provide individualized support at the beginning of a training program to promote adherence. Overall, there is no one-size fits all exercise modality; however, HIIT may be an enjoyable, time-efficient alternative to MICT.
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Dunston, Emily R., "Physiological and psychological responses to six weeks of high-intensity interval and moderate-intensity continuous training in physically inactive young adults" (2020). EWU Masters Thesis Collection. 617.