Compare the effect of high-intensity interval and moderate-intensity continuous exercise on sleep characteristics, appetite-related hormones and eating behaviour. 11 overweight, inactive men completed two consecutive nights of sleep assessments to determine baseline (BASE) sleep stages and arousals recorded by polysomnography (PSG). On separate afternoons (1400-1600h), participants completed a 30min exercise bout: 1) moderate-intensity continuous exercise (MICE; 60% VȮ 2peak ) or 2)

more »

... ty interval exercise (HIIE; 60s work at 100% VȮ 2peak : 240s rest at 50% VȮ 2peak ), in a randomised order. Measures included appetite-related hormones (acylated ghrelin, leptin, peptide tyrosine tyrosine) and glucose pre-exercise, 30min post-exercise, and the next morning post-exercise; PSG sleep stages, actigraphy (sleep quantity and quality), and self-reported sleep and food diaries were recorded until 48h post-exercise. There was no between-trial differences for time in bed (p=0.19) or total sleep time (p=0.99). For HIIE, stage N3 sleep was greater (21 ± 7%) compared to BASE (18 ± 7%; p=0.02). Also, number of arousals during rapid eye movement sleep were lower for HIIE (7 ± 5) compared to BASE (11 ± 7; p=0.05). Wake after sleep onset was lower following MICE (41min) compared to BASE (56min; p=0.02). Acylated ghrelin was lower and glucose higher at 30min post-exercise for HIIE compared to MICE (p≤0.05). There were no significant differences in total energy intake between conditions (p≥0.05). HIIE appears more beneficial than MICE for improving sleep quality and inducing favourable transient changes in appetiterelated hormones in overweight, inactive men. However, energy intake was not altered regardless of exercise intensity. There was no trial × time interaction for perceived hunger (p = 0.29; Figure 3A ) or fullness (p = 0.73; Figure 3B ). However, there was a main effect of time for both trials whereby hunger was higher and fullness was lower the morning after-exercise compared with pre-exercise ratings (p ≤ 0.02). The hormone and glucose responses to MICE and HIIE are shown in Figure 4 . There was a trial × time interaction for acylated ghrelin, with post hoc analyses revealing significantly higher acylated ghrelin preexercise for HIIE compared to MICE (p = 0.001), and lower ghrelin at 30 min post-exercise for HIIE compared to MICE (p = 0.03; Figure 4A ). There was also a trial × time interaction for glucose, with higher concentrations at 30 min post-exercise for HIIE compared to MICE (p = 0.02; Figure 4D ). There was no trial × time interaction for leptin or PYY total (p > 0.05), although there was a main effect of time for leptin with higher concentrations the morning post-exercise compared to 30 min post-exercise (p = 0.05; Figure 4B ). Flint, A., Gregersen, N.T., Gluud, L.L., Møller, B.K., Raben, A., Tetens, I., et al. 2007. Associations between postprandial insulin and blood glucose responses, appetite sensations and energy intake in normal weight and overweight individuals: a meta-analysis of test meal studies. Br. J. Nutr. 98(1): 17-25. . 2000. Reproducibility, power and validity of visual analogue scales in assessment of appetite sensations in single test meal studies. Int. J. Obes. Relat. Metab. Disord. 24(1): 38-48. , et al. 2007. Aerobic high-intensity intervals improve VO 2max more than moderate training. Med. Sci. Sports Exerc. 39(4): 665. Hirshkowitz, M., Whiton, K., Albert, S.M., Alessi, C., Bruni, O., DonCarlos, L., et al. 2015. National Sleep Foundation's sleep time duration recommendations: methodology and results summary. Sleep Health, 1(1): 40-43.