Hormonal Responses to Consecutive Carbohydrate Ingestions during Heavy-Resistance Exercise

Jung HL, Ryu JS, Kang HY. Hormonal Responses to Consecutive Carbohydrate Ingestions during Heavy-Resistance Exercise. JEPonline 2018;21(5):97–108. The purpose of this study was to study investigates plasma hormonal responses to consecutive carbohydrate supplementations during heavy-resistance exercise. Ten male students randomly received either exercise treatment (8 RM) or exercise/carbohydrate (8 RM/CHO). The 8 RM/CHO group ingested carbohydrate (1.2 g·kg⁻¹) between resistance exercise sessions. Each session consisted of 5 sets of leg press exercise with a maximum of 8 reps (8 RM), and there were four sessions during the 2hr experimental period. Blood samples were drawn immediately before exercise (0) and in 15-min intervals during the 2hr period. Plasma total testosterone, cortisol, human growth hormone (hGH), insulin, and glucose concentrations were determined. The plasma glucose level was significantly higher in 8 RM/CHO at 15, 30, 45, 60, and 90 min versus 8 RM (P<0.05). Testosterone level decreased significantly in 8RM/CHO (P<0.05) through the end of the experimental period, but there was no change in 8 RM. Plasma insulin level was significantly elevated in 8 RM/CHO (P<0.05) until the end of the experimental period, but there was no change in 8 RM. Plasma hGH level in 8 RM was significantly elevated between 30 and 90 min (P<0.05), but this elevation was completely blocked in 8 RM/CHO. There was no significant difference in the cortisol level between the two treatment methods. These results suggest that the consecutive ingestion of carbohydrate during resistance exercise reduced the level of total testosterone, blocked the elevation of hGH, and increased the insulin level.