Modified sprint interval training protocols. Part I. Physiological responses

Abstract

Adaptations to sprint interval training (SIT) are observed with brief (≤15-s) work bouts highlighting peak power generation as an important metabolic stimulus. This study examined the effects of manipulating SIT work bout and recovery period duration on energy expenditure (EE) during and postexercise, as well as postexercise fat oxidation rates. Nine active males completed a resting control session (CTRL) and 3 SIT sessions in randomized order: (i) 30:240 (4 × 30-s bouts, 240-s recovery); (ii) 15:120 (8 × 15-s bouts, 120-s recovery); (3) 5:40 (24 × 5-s bouts, 40-s recovery). Protocols were matched for the total duration of work (2 min) and recovery (16 min), as well as the work-to-recovery ratio (1:8 s). EE and fat oxidation rates were derived from gas exchange measured before, during, and for 3 h postexercise. All protocols increased EE versus CTRL (P < 0.001). Exercise EE was greater (P < 0.001) with 5:40 (209 kcal) versus both 15:120 (163 kcal) and 30:240 (138 kcal), while 15:120 was also greater (P < 0.001) than 30:240. Postexercise EE was greater (P = 0.014) with 15:120 (313 kcal) versus 5:40 (294 kcal), though both were similar (P > 0.077) to 30:240 (309 kcal). Postexercise fat oxidation was similar (P = 0.650) after 15:120 (0.104 g·min −1 ) and 30:240 (0.116 g·min −1 ) and both were greater (P < 0.030) than 5:40 (0.072 g·min −1 ) and CTRL (0.049 g·min −1 ). In conclusion, shorter SIT work bouts that target peak power generation increase exercise EE without compromising postexercise EE, though longer bouts promote greater postexercise fat utilization.Key words: high-intensity interval training, energy expenditure, excess postexercise oxygen consumption, fat oxidation, repeated sprint exercise, peak power generation. Mots-clés : entraînement par intervalle d'intensité élevée, dépense énergétique, consommation d'oxygène postexercice en surplus, oxydation des graisses, exercice de sprint répété, production de puissance de pointe.

Modified sprint interval training protocols. Part II. Psychological responses

“…A fourth experimental session served to determine participants' preference where they were asked to indicate the protocol they would prefer to perform again (i.e., a behavioural choice, though after selecting they were not required to perform the exercise). In our companion paper (Islam et al 2017) we report greater energy expenditure during shortened SIT bouts. In the present paper, we hypothesized that shorter intervals would elicit more positive affective responses and be evaluated more positively than the traditional SIT paradigm.…”

“…The PACES scale was modified similar to Jung et al (2014) by removing 1 irrelevant item (current absorption in the activity) and adding 2 questions (see Table 2). Participants in the current project were wearing a respiratory mask for 30 min postexercise (Islam et al 2017). Thus, to avoid any confounding factors, we waited until the mask was removed to assess perceptions of the exercise.…”

“…1. Sample timeline of experimental session relative to companion paper (Islam et al 2017). Arrows indicate measurement time points.…”

“…All participants also participated in a fourth session that served as a behavioural choice follow-up session. The relatively small sample size reflects that data collection was in conjunction with our physiological companion paper (Islam et al 2017). Participants were nonsmokers, recreationally active (≤3 sessions/week), not currently engaged in an exercise-training program at the time of data collection (or for 4 months prior), and used no dietary supplements.…”

“…This included gathering baseline height and weight, familiarization with questionnaire instruments, and practice using the self-propelled treadmill on which all training would occur (HiTrainer, Que., Canada). Prior to beginning the experimental sessions all participants performed a graded exercise test to determine V O 2max (Islam et al 2017).…”