The effect of hydroxy-beta-methylbutyrate and caffeine supplementation on growth hormone levels following resistance exercise in obese women

Objectives: Growth hormone (GH) response in obese individuals is limited during acute exercise. The aim of the present study was to investigate the effect of HMB and caffeine supplementation on GH concentrations following intense resistance exercise in obese women.
Methods & Materials: Eleven obese women (age 45.4±4.8 years, weight 98.1±8.3 kg, height 162.1±4.7 m, and body fat percentage 42.4±4.5) volunteered to participate in this study. Subjects performed an acute resistance exercise test at 80% intensity for one repetition maximum in four conditions of placebo (P), 3 g HMB (H), 6 mg/kg body weight caffeine (C), and a combination of HMB and caffeine (HC). HMB was consumed 30 min and caffeine 1 h before the test. Blood samples were collected before supplementation or placebo, immediately after exercise, and 30 min after exercise.
Results: The mean GH concentration in the H condition was significant (F=23.27, p=0.001) and in which GH was significantly higher than resting levels (p=0.001) and 30 minutes after exercise (p=0.003). GH did not change significantly in other conditions including C, P and HC conditions (p>0.05). The changes in mean insulin and glucose levels in the different test conditions were not significant (p>0.05).
Conclusion: HMB supplementation may be associated with increased GH levels during intense resistance exercise in obese women. Caffeine probably does not affect the GH response in obese women. HMB and caffeine supplementation do not affect insulin and glucose levels.