Effects of chromium and resistive training on muscle strength and body composition

Sixteen untrained males (23 ± 4 yr), were studied to determine the effects of chromium (Cr) supplementation (200 μg · d-1) and a 12-wk resistive exercise training program on muscle strength, body composition, and Cr excretion. The subjects trained 3 times per week with two sets of 8-10 repetitions at 90% of 1 repetition maximum using Keiser variable resistance machines. Food records were used to estimate Cr intake (36μg · d-1), energy intake, and the percent kJ from protein. The resistive training program resulted in significant increases in total body muscular strength in both the Cr and placebo groups (24% and 33%; P< 0.05). Body weight, percent body fat, lean body mass, and skinfold thicknesses were unchanged in either group after resistive training. Cr excretion increased in the Cr group after 6 wk of Cr supplementation (0.15± 0.08 vs 1.52 ± 1.26 μg · d-1; P< 0.01) and remained higher at 12 wk of training (2.03 ± 1.73). These results indicate that Cr supplementation, in conjunction with a progressive, resistive exercise training program, does not promote a significant increase in strength and lean body mass, or a significant decrease in percent body fat. Cr supplementation results in a significant increase in Cr excretion that is not altered by resistive training.