Effects of blocked and periodic interval training on cardiorespiratory fitness and affective responses among college students

William Ryota Yaku

doi:10.7273/000006983

Physical activity (PA), defined as any bodily movement produced by the contraction of skeletal muscle that increases energy expenditure above a basal level, is negatively associated with adverse health outcomes and positively associated with health and fitness. However, 46% of all American adults are not meeting aerobic PA guidelines (i.e., 150 minutes of moderate-intensity activity, 75 minutes of vigorous-intensity activity, or equivalent combination), and of those not meeting guidelines, more than half do not engage in any purposeful aerobic PA whatsoever. Perceived lack of time is the most cited barrier to PA in young adults and may partially explain the above findings. Interval training (IT) has emerged as an effective, time-efficient mode of exercise to potentially attenuate the time barrier, thus enabling young adults to meet PA guidelines. The purpose of this study was to compare different weekly frequencies of interval training on cardiorespiratory fitness adaptations and affective responses among university students. Fourteen students were recruited and randomly assigned into a six-week exercise intervention group. The “blocked” group (HIIT1) performed the weekly recommended exercise volume in one session every week. The “periodic” group (HIIT3) performed the same volume spread out across three weekly sessions. The intensity of the intervention sessions was set at 80% of V̇O2max for each participant. Baseline and post-intervention graded exercise testing were conducted to compare differences in cardiorespiratory fitness (V̇O2max) improvements. Affective responses were assessed by rating of perceived exertion (RPE) and the Feeling Scale (FS) and were measured within the intervention. Both groups experienced significant (p < 0.05) increases in V̇O2max, with the greatest effect observed in the HIIT3 group (HIIT1, +8.2% ± 6.8%; HIIT3, +11.3% ± 9.2%; p = 0.04). RPE average across the intervention was significantly higher in the HIIT1 group (HIIT1: 6.3 ± 2.1, HIIT3: 3.2 ± 2.3, p < 0.001). FS score session averages, on the other hand, were lower for HIIT1 than HIIT3 (HIIT1: -0.2 ± 1.4, HIIT3: 3.5 ± 0.6, p < 0.001). Interestingly, neither RPE nor FS scores changed across the intervention in the HIIT3 group (p > 0.05 for both), whereas the HIIT1 group experienced decreases in RPE (-2.4 ± 0.4, p = 0.02) and increases in FS score (+3.6 ± 0.8, p = 0.008). The present study demonstrated that the V̇O2max improvement was greater in the HIIT3 group compared to the HIIT1 group even with matched relative intensity and weekly exercise volume. Additionally, the HIIT3 group had more adaptive affective responses throughout the intervention. These findings suggest that spreading a weekly volume of exercise across multiple days may be superior to completing it in one session in terms of both cardiorespiratory fitness improvement and affective responses.

Effects of blocked and periodic interval training on cardiorespiratory fitness and affective responses among college students

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