Sex Differences In Total Pyy And Glp-1 After Moderate-intensity Continuous And Sprint Interval Cycling Exercise.

Abstract

Exercise is often used as a weight-loss strategy, however, exercise interventions are sometimes less effective in females than males for improving body composition. One possible explanation is that exercise affects appetite regulating hormones differently in males and females such that females increase post-exercise energy intake. Recently, sprint interval training was shown to reduce body fat in females despite relatively low energy expenditure during exercise. PURPOSE: To examine sex differences in circulating anorexigenic hormones and perceived hunger following an acute session of sprint interval training (SIT) and moderate-intensity continuous training (MICT). METHODS: Twenty-one active participants (11 females in early follicular phase) participated in 3 sessions in a randomized crossover design: 1) MICT, 30 min cycling at 65% VO2max; 2) SIT, 6 x 30 sec “all-out” cycling sprints with 4 min recovery periods (27 min total); and 3) control (CTRL; no exercise). Participants arrived at the lab fasted and consumed a standardized breakfast 1 hour before exercise. Blood samples were collected pre-exercise, immediately and 90 min post-exercise for the measurement of total peptide tyrosine tyrosine (PYY) and glucagon-like peptide-1 (GLP-1). Subjective perceptions of hunger were assessed using a visual analogue scale before breakfast and before all blood draws. Hormone data were analysed as change in concentration from baseline. Changes in hormones and hunger were analysed using a 3 x 3 x 2 mixed factor (session x time x sex) repeated measures ANOVA. RESULTS: Increases in GLP-1 and PYY were greater during the MICT session (P<0.05) and SIT session (P<0.01) compared to CTRL. Total PYY increased more immediately post-exercise in males than females (P=0.030). GLP-1 increased only 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, but there were no sex differences. CONCLUSION: Total PYY and GLP-1 appear to respond similarly to submaximal and supramaximal exercise, however, these results suggest they may respond differently to exercise in males and females over 90 min. The post-exercise hormonal response we observed in females would not be expected to create a compensatory increase in energy intake.