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Exercise interventions are often less effective at improving body composition for females than males, potentially due to post-exercise hormonal responses that increase energy intake in females. Recently, sprint interval training was shown to effectively reduce body fat in females despite being relatively low during exercise energy expenditure. To determine whether any sex difference in total PYY, GLP-1 or perceived hunger exists following moderate-intensity continuous exercise (MICT) and sprint interval exercise (SIT) Twenty-one active participants (11 females) participated in three sessions in a randomized crossover design: (1) MICT, 30-min cycling at 65% VO2max; (2) SIT, 6 × 30 s “all-out” sprints with 4-min recovery periods; (3) control (CTRL; no exercise). Blood samples were collected pre-exercise, immediately and 90 min post-exercise for the measurement of total PYY and GLP-1. Subjective perceptions of hunger were assessed using a visual analogue scale pre-breakfast and before all blood samples. Concentrations of total PYY and GLP-1 were greater during MICT (P = 0.05) and SIT (P = 0.005) compared to CTRL. Total PYY increased more immediately post-exercise in males than females (P = 0.030). GLP-1 only increased in females following MICT (P = 0.034) and SIT (P = 0.024) compared to CTRL. Perceived hunger was lower immediately post-MICT (P = 0.016) and SIT (P = 0.006) compared to CTRL. These results suggest that total PYY and GLP-1 respond differently to exercise in males and females over 90 min following various exercise intensities. The observed post-exercise hormonal response would not be expected to create a compensatory increase in energy intake in females.

Sprint interval training (SIT) can elicit improvements in aerobic and anaerobic capacity. While variations in SIT protocols have been investigated, the influence of social processes cannot be overlooked. As research supports the use of groups to influence individual cognitions and behaviours, the current project assessed the effectiveness of a group-based intervention with participants conducting SIT. Specifically, 53 amateur athletes (age, 21.9 ± 2.9 years; 53% females) took part in a 4-week training program (3 sessions per week, 30-s “all-out” efforts with 4 min active recovery, repeated 4–6 times per session), and were assigned to “true group”, aggregate, or individual conditions. Results indicated no significant differences between groups for the physiological measures. With regards to training improvements from baseline for all participants— regardless of condition — significant main effects for time were identified for maximal oxygen uptake (2.5–2.8 mL·kg−1·min−1, p < 0.001, η2 = 0.03), time-trial performance (14–32 s, p < 0.001, η2 = 0.37), and anaerobic power (1.1–1.7 k·h−1, p < 0.001, η2 = 0.66). With regards to the psychological measures, significant main effects between groups were found for motivation (p = 0.033, η2 = 0.13), task self-efficacy (p = 0.018, η2 = 0.15), and scheduling self-efficacy (p = 0.003, η2 = 0.22). The true group experienced greater improvements in motivation than the individual condition, but the aggregate and individual conditions demonstrated greater increases in task and scheduling self-efficacy. Though the SIT paradigm employed induced training improvements similar to previous work, the group intervention was not able to further these improvements.