The effects of intermittent liquid meal feeding on selected hormones and substrates during intense weight training

This study examined the effects of feeding a liquid meal during weight training on selected hormones and substrates. Ten male subjects were given a meal (MW) or nonnutritive placebo (W) before and intermittently during a 2-hr weight training session, and a meal before and intermittently during 2 hours of rest (M). Serum insulin increased from 12.2 +/- 1.2 and 11.2 +/- 1.3 before feeding to 37.2 +/- 4.8 and 45.0 +/- 5.0 mU.ml-1 during exercise in MW and M, respectively, and remained elevated for 120 min. Insulin remained at resting levels in W throughout the experiment. Glucose increased from 5.20 +/- 0.16 and 4.82 +/- 0.20 before feeding to 6.23 +/- 0.30 and 6.0 +/- 0.36 mmol.l-1 at the beginning of exercise in MW and M. Glucose declined during the first 15 min of exercise in MW and M but remained at or above resting levels for 120 min in MW. Lactate increased above 5.9 mmol.l-1 in W and MW during exercise. Glucagon remained unchanged in all groups. Perceived exertion during exercise was 8.5 +/- 0.16 for MW and 8.3 +/- 0.18 for W. Feeding a liquid meal before and during weight training exercise can increase serum insulin and maintain blood glucose for a prolonged period.