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 · 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 1−1 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 · 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.
Fahey, Hoffman, and Colvin are with the Exercise Physiology Lab, Dept. of Physical Education, California State University, Chico, Chico, CA 95926. Lauten is with the Dept. of Radiology at Chico Community Hospital, Chico, CA 95926.