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Thomas D. Fahey, Karen Hoffman, William Colvin and Gregory Lauten

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 · ml1 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 · I1 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.

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Thomas D. Fahey, James D. Larsen, George A. Brooks, William Colvin, Steven Henderson and Darrel Lary

Five trained, fasted male cyclists rode a cycle ergometer three times at 50% of VO2,max for 180 min. Using a balanced order, double-blind procedure,subjects were given either a solution containing polylactate (PL: 80% polylactate, 20% sodium lactate, in 7% solution with water), glucose polymer (GP: multidextrin in 7% solution with water), or control (C: water sweetened with aspartame) 5 min before exercise and at 20-min intervals during exercise. Venous blood samples were taken at rest and at 20-min intervals during exercise. In general, PL and GP rendered similar results except that pH and bicarbonate (HCO3) were higher in PL. There were no differences between treatments in perceived exertion, sodium, potassium, chloride, lactate, heart rate, oxygen consumption, rectal temperature, or selected skin temperatures. These data show that polylactate may help maintain blood glucose and enhance blood buffering capacity during prolonged exercise and could be a useful component in an athletic fluid replacement beverage.