Document Type

Thesis

Degree Name

Master of Science (MSc)

Department

Kinesiology and Physical Education

Faculty/School

Faculty of Science

First Advisor

Dr. Tom Hazell

Advisor Role

Supervisor

Abstract

Interleukin-6 (IL-6) stimulates the release of appetite-regulating hormones in animals and associates with decreased energy intake in humans. Thus, IL-6 may contribute to the intensity- dependent effects of exercise on appetite-related parameters. The purpose of this study was to examine the effects of exercise intensity on IL-6, appetite-regulating hormones, and appetite perceptions. Eight active young males completed four sessions: 1) Moderate-intensity continuous training (MICT; 30 min running, 65% VO2max); 2) High-intensity continuous training (HICT; 30 min running, 85% VO2max); 3) Sprint interval training (SIT; 4 x 30 sec “all-out” running bouts separated by 4 min recovery); 4) Control (CTRL; no exercise). Blood samples were obtained immediately pre- and post-exercise, as well as 30- and 90-min post-exercise for the measurement of acylated ghrelin, active glucagon-like peptide-1 (GLP-1), and IL-6. Appetite perceptions were assessed at the same time-points using a visual analog scale. Energy intake was recorded for a 3-day period beginning on the day before each session. Acylated ghrelin and appetite were suppressed after HICT (P<0.005) and SIT (P<0.002), though more so after SIT compared to MICT (P<0.042). Active GLP-1 concentrations increased immediately after MICT (P<0.001) and 30 min after HICT (P<0.001) and SIT (P=0.005). Intensity-dependent increases in IL-6 coincided with decreases in acylated ghrelin and correlated negatively with appetite after HICT. Though not correlated, simultaneous increases in GLP-1 and IL-6 were observed 30 min after HICT and SIT. Free-living energy intake was reduced on the day after HICT compared to both MICT (P=0.028) and CTRL (P=0.020). These findings support an intensity-dependent paradigm for appetite-regulation that is strongly associated with changes in acylated ghrelin and may be mediated by IL-6.

Convocation Year

2016

Convocation Season

Fall

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