Submitted to: International Journal of Sport Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/20/2003
Publication Date: 3/20/2004
Citation: Campbell, W., Lyndon, J., Ostlund, R., Anderson, R.A., Farrell, P., Evans, W. 2004. Exercise Metabolism. International Journal of Sport Nutrition. 14:430-442. Interpretive Summary: Poor control of blood sugar and lack of sufficient resistive exercise or weight training are serious problems in elderly people. Resistive training , chromium picolinate supplementation, and selected inositols, also known as muscle sugars, may all influence insulin-and blood sugar. The urinary excretion of the muscle sugars are higher in persons with poor versus good control of blood sugars. This study was designed to determine the combined effects of resistive training and chromium picolinate supplementation on the excretion of different forms of muscle sugars and to document the safety of chromium picolinate. Thirty-two older, moderately obese, non-diabetic, people ,17 M 15 F, 62 +/- 4 yr , performed weight bearing exercise twice weekly for 12 weeks, and were randomly assigned to groups that consumed either 924 g Cr/d as chromium picolinate or a placebo. A 20% increase in whole body strength in all subjects and a 47-fold increase in urinary chromium excretion in the chromium group attested to the effectiveness of the resistive training and chromium supplementation. With strength training, insulin decreased by 19 % but chromium did not affect any measure of glucose metabolism. The urinary excretions of muscle sugars also were not changed with strength training or chromium. Sensitive indexes of kidney and liver functions were also unchanged by chromium. Lack of a response to chromium appeared to be due to the high basal intake of the subjects. This study is a particular interest to the millions of people taking chromium supplements since these data demonstrate the safety of chromium even at levels more than 20-fold the new adequate intakes.
Technical Abstract: Resistive exercise training (RT), chromium picolinate (Cr-pic) supplementation, and selected inositols may all influence insulin-mediated glucose metabolism. One aim of this study was to assess the effects of 12 weeks of RT and Cr-pic on the 24-hour urinary excretions of myo-inositol, D-chiro-inositol, and pinitol. Since the potential for high-dose Cr-pic supplementation to adversely effect kidney and liver functions in humans has been questioned, a second aim was to assess clinical indexes of kidney and liver function. Thirty-two older, moderately obese, non-diabetic, people,17 M and 15 F, 62 +/- 4 yr, body mass index 29.1 2.5 kg/m2, performed RT twice weekly for 12 weeks, and were randomly assigned to groups that consumed either 924 g Cr/d as Cr-pic or a placebo. A 20% increase in whole body strength in all subjects and a 47-fold increase in urinary chromium excretion in the Cr-RT group attested to the effectiveness of the RT and Cr-pic supplementation, respectively. With RT, insulin decreased by 19% but Cr-pic did not affect any measure of glucose metabolism. The urinary excretions of myo-inositol, D-chiro-inositol, and pinitol were not changed with RT or influenced by Cr-pic. Serum indexes of kidney and liver functions were not changed by supplemental chromium. In summary, a RT program decreased the insulin response but not the urinary excretions of myo-inositol, D-chiro-inositol, or pinitol. High-dose Cr-pic supplementation did not influence the excretion of these inositols and the selected indexes of kidney and liver function substantiating the safety of supplemental chromium.