Medicine & Science in Sports & Exercise:
Bone and Aletered Mechanical Loading: Basic Science Approaches
McCarty, H L.1; Story, R1; Reed, A H.1; Evans, G L.1; Turner, R T.1; Westerlind, K C. FACSM1
1AMC Cancer Research Center, Denver, CO and Mayo Clinic, Rochester, MN
Alcohol consumption results in marked reductions in bone formation and bone mass. Previous evidence suggests that running does not attenuate the effects of alcohol. Rather, alcohol consumption may accentuate the inherent skeletal risks (e.g., microcracks, stress fractures) associated with running. Resistance exercise has been reported to result in increased bone mass yet the interaction w/alcohol consumption has not been evaluated.
To assess the independent and interactive effects of resistance training and alcohol consumption on the skeleton. It was hypothesized that resistance training would mitigate the negative effects of alcohol.
Forty-eight 6 mos-old male Sprague-Dawley rats were stratified by wt and randomized to exercise (EX), exercise with alcohol diet (EX-etoh), sedentary (SED), or sedentary with alcohol diet (SED-etoh) groups. Alcohol-fed rats received Bio-Serv Liquid Rat Diet LD '82 (35% of kcal from alcohol). Control animals were pair fed a liquid diet with maltose-dextrin as caloric substitute. Resistance training consisted of performing “squats” wearing a weighted vest. Over the 6-wk training period, animals performed 30 reps/session, 3 sessions/wk. Loads were increased weekly from 20% bw to 120% bw (final vest wt – 602g). Fluorochrome labels were administered prior to starting the training and 10 and 2 d prior to sacrifice for static and dynamic bone histomorphometry.
In cortical bone, alcohol consumption resulted in reduced bone formation and increased medullary area. Resistance training attenuated the reduction in periosteal bone formation in the alcohol groups (29.3% EX-etoh vs. 18.3% SED-etoh; p = 0.03). This is in contrast to our previous study in which running exercise did not attenuate the alcohol-associated reduced bone formation. In the cancellous bone, alcohol consumption resulted in markedly reduced bone formation rates (−85%; p < 0.01). However, in contrast to the cortical bone, 6 wks of resistance training did not mitigate the negative effects of alcohol.
Alcohol and resistance training appear to have independent tissue-specific effects on bone formation and bone mass. Supported by DOD-DAMD 17-98-1-8517, NASA, and the Mayo Foundation.