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.
Hallmark
M A
MA
Department of Kinesiology, University of Maryland, College Park, USA.
Reynolds
T H
TH
DeSouza
C A
CA
Dotson
C O
CO
Anderson
R A
RA
Rogers
M A
MA
D000328:Adult; D001823:Body Composition; D002857:Chromium / Q000494:pharmacology*; D004311:Double-Blind Method; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000187:drug effects*; D014891:Weight Lifting / Q000502:physiology*
D002857:Chromium