Submitted to: American Journal of Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/27/1998
Publication Date: N/A
Citation: N/A Interpretive Summary: Aging leads to loss of muscle mass and strength which is associated with decreased mobility. Resistance exercise and chromium have both been shown to increase these variables. This study was conducted to determine if chromium supplementation increased the effects of resistance exercise on lean body mass and related variables of older men, 56 to 69 years. Twelve weeks of resistive exercise increased fat-free mass, muscle mass and related variables but additional effects due to supplemental chromium were not significant. However, dietary intake of control diets of these subjects was two to three times the normal US intake and may have minimized the effects of supplemental chromium. In summary, these data demonstrate that, even in older men, resistive exercise increases muscle size, strength and power but the additional proposed effects of supplemental chromium were not confirmed. These results are of benefit to the millions of senior citizens who do or will suffer the consequences of reduced muscle size and power associated with aging.
Technical Abstract: The effects of chromium picolinate (Cr-pic) supplementation and resistance training (RT) on skeletal muscle size, strength, and power, and whole body composition were examined in 18 men, age range 56-69 y. The men were randomly assigned (double-blind) to groups (n=9) that consumed either 17.8 umol Cr/d (924 ug Cr/d) as Cr-pic or a low-Cr placebo for 12 wk while participating twice weekly in a high-intensity RT program. Cr-pic increased urinary Cr excretion about 50-fold (P<0.001). RT-induced increases in muscle strength (P<0.001) were not enhanced by Cr-pic. Arm pull muscle power increased with RT at 20% (P=0.016), but not at 40%, 60%, or 80% of the one repetition maximum (1RM), independent of Cr-pic. Knee extension muscle power increased with RT at 20%, 40%, and 60% (P<0.001), but not at 80% of 1RM, and the placebo group gained more muscle power than the Cr-pic group (RT-by-Suppl. interaction, P<0.05). Fat-free mass (P<0.001), protein plus mineral mass (P<0.001), muscle mass (P<0.001), and type II fiber area (P<0.05), increased with RT in these body weight-stable men, independent of Cr-pic. In conclusion, high-dose chromium picolinate supplementation did not enhance muscle size, strength or power development or lean body mass accretion by older men during a resistance training program which had significant, independent effects on these measures.