Null effect of ginsenoside Rb1 on improving glycemic status in men during a resistance training recovery

BACKGROUND Ginsenoside Rb1, a principle active ingredients of Panax ginseng, has been shown to lower blood glucose in animals and increase insulin secretion in cultured insulinoma cells. The aim of this study was to determine the effects of daily ginsenoside Rb1 supplementation on circulating glucose and insulin levels in men during a 5-day recovery period after an acute bout of resistance exercise. METHODS Twelve gymnasts (20.5 ± 0.3 years of age) participated in this double blind placebo-controlled crossover trial. They were challenged by a lower-limb resistance exercise at a weight load of 85 % one-repetition maximal (1-RM) for 10 repetitions, six sets of the movement. Rb1 (1 ng/kg) or Placebo was orally delivered to participants daily during a 5-day recovery period after challenge. Circulating insulin, glucose and heart rate variability (HRV) were measured under fasted condition in the morning at Days 1, Day 3, and Day 5 during recovery. RESULTS No significant effect of Rb1 on circulating glucose and insulin levels were found among participants during the 5-day recovery period. A persistent elevation in sympathetic nervous activity, indicated by increased HRV-low frequency/high frequency (HRV-LF/HF) power, during the Rb1 trial was observed. CONCLUSIONS The result of the study suggests that the null effect of Rb1 supplementation on lowering glucose and insulin levels of participants may be associated with chronic sympathetic activation.