Effects of carbohydrate and chromium ingestion during intermittent high-intensity exercise to fatigue

Purpose: This study was designed to test the hypothesis that addition of chromium (Cr) to a carbohydrate-electrolyte drink would enhance the reported benefits of carbohydrate on exercise capacity during intermittent high-intensity shuttle running. Methods: Eight physically active men performed 3 exercise trials while ingesting 6% carbohydrate-electrolyte (CHO), CHO plus chromium picolinate (400 mug) (CHO + Cr+3), or placebo (P) using a double-blind, counterbalanced design. Each trial consisted of 5 x 15 min bouts of shuttle running (walk, sprint, and run at 95 and 55% of estimated (V) over dot O-2max, separated by 3-min rest). This was followed by a fatigue test (running alternating 20-m lengths at 55 and 95% of estimated (V) over dot O-2max until fatigue). Results: During the standardized shuttle running, blood glucose was higher with both CHO and CHO + Cr+3 than P. Plasma free fatty acid was higher in P than both CHO and CHO + Cr+3 at 75 min of exercise and at fatigue. In the fatigue test, subjects ran longer with both CHO and CHO + Cr+3 than P. Conclusions: The data confirm an ergogenic benefit of ingesting CHO during exercise designed to imitate sports like basketball, soccer. and hockey, but do not support the hypothesis that the addition of Cr would enhance this effect.