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.
Exercise Physiology Laboratory, Department of Kinesiology, University of Maryland, College Park, MD; and Vitamin and Mineral Nutrition Laboratory, Beltsville Human Nutrition Research Center, USDA, Beltsville, MD
Submitted for publication October 1993.
Accepted for publication February 1995.
The Cr picolinate supplement and placebo capsules were generously supplied by Nutrition 21, San Diego, CA. We appreciate the technical assistance of Noella Bryden in performing the urinary Cr assay and thank Sacared Bodison, M.D., from the Student Health Center and Colleen Farmer, Ph.D., from the Wellness Research Laboratory for the use of their facilities.
Address for correspondence: Marc A. Rogers, Ph.D., Department of Kinesiology, University of Maryland, College Park, MD 20742-2611; E-mail:MR68@UMAIL.UMD.EDU.