WoCA Projects, Building Communities Through Exhibitioning: Curating and Creating Spaces for Women Artists of Color
Deemer, Sarah E.
MetadataShow full item record
There is a strong positive relationship between exercise intensity and pulsatile GH release. It has yet to be determined if high-intensity interval exercise (HIE) can influence pulsatile GH secretion, especially overnight, which accounts for the majority of daily GH release. The purpose of this study was to determine if HIE significantly increased GH secretion compared to continuous moderate-intensity exercise (MOD), or no exercise (CON) in young women. Five young, sedentary women (mean ± SD age: 22.6 ± 1.3 years; BMI: 27.4 ± 3.1 kg/m2; body fat: 39.2 ± 1.7%; VO 2max: 29.4 ± 5.7 ml/kg/min) were studied on three different occasions during the follicular phase of their menstrual cycle (CON: no exercise; MOD: 30-min of continuous cycling at 50% of peak power determined from the VO 2max test; and HIE: 4 30-s “all-out” sprints with 4.5 min of recovery between each sprint). Each trial was randomly assigned and separated by a minimum of one month. For each visit, participants reported to the lab at 1700 hr, exercised from 1730 – 1800 hr, and remained in the lab until 0700 hr the following morning. The overnight GH secretory profile of each trial was determined from 10-min sampling of venous blood from 1730 – 0600 hr (12.5 h) using deconvolution analysis. Deconvolution GH parameters were log transformed prior to statistical analyses. Calculated GH AUC (0 – 120 min) was significantly greater in HIE (1018.2 ± 576.1 ng/mL/120 min) than CON (181.7 ± 138.9 ng/mL/120 min, p = .04), but not MOD (544.7 ± 160.7 ng/mL/120 min). Total GH secretory rate (ng/mL/12.5 h) was significantly different between CON (1040.3 ± 242.0) and HIE (1831.2 ± 873.8, p = .05), but MOD (1429.2 ± 206.0) was not different from CON (p = .08). For these untrained, overweight, sedentary young women, a single bout of exercise was insufficient to significantly affect overnight pulsatile GH secretion. Aerobic fitness, prior training, as well as several metabolic factors associated with obesity (e.g., increased insulin and circulating free fatty acids), can also influence GH secretion and should be taken into account as potential mediators of the GH response to exercise.