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

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 micrograms.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 (approximately 36 micrograms.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 micrograms.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.

对16名未经训练的男性（23±4岁）进行了研究，以确定补充铬（每日200微克）以及为期12周的抗阻运动训练计划对肌肉力量、身体成分和铬排泄的影响。受试者每周训练3次，使用凯泽可变阻力器械，以1次最大重复量的90%进行2组，每组8 - 10次重复。通过食物记录来估算铬摄入量（约每日36微克）、能量摄入以及来自蛋白质的千焦百分比。抗阻训练计划使铬补充组和安慰剂组的全身肌肉力量均显著增加（分别为24%和33%；P < 0.05）。抗阻训练后，两组的体重、体脂百分比、瘦体重和皮褶厚度均无变化。铬补充组在补充铬6周后铬排泄增加（0.15±0.08微克/日对比1.52±1.26微克/日；P < 0.01），并且在训练12周时仍保持较高水平（2.03±1.73微克/日）。这些结果表明，铬补充结合渐进性的抗阻运动训练计划，并不会使力量和瘦体重显著增加，也不会使体脂百分比显著降低。铬补充会使铬排泄显著增加，且抗阻训练不会改变这种情况。