A Prospective Study of Weight Training and Risk of Type 2 Diabetes Mellitus in Men
Is there a role for weight training in the primary prevention of type 2 diabetes mellitus (T2DM)?
A prospective cohort study was conducted in 32,002 men (ages 40-75 years) from the Health Professionals Follow-up Study, observed from 1990 to 2008. The authors analyzed the association of weight training with risk of T2DM in men, and the influence of combining weight training and aerobic exercise. Weekly time spent on weight training and aerobic exercise (including brisk walking, jogging, running, bicycling, swimming, tennis, squash, and calisthenics/rowing) was obtained from questionnaires at baseline and biennially during follow-up. Relative risks (RRs) of T2DM by categories of weight training and aerobic exercise were estimated using time-dependent Cox proportional hazards regression stratified jointly by age (in months) at the start of follow-up and the year of questionnaire return.
A total of 96% were white, 15% had a family history of diabetes, and participants were otherwise low risk for diabetes based on body mass index and nutrition. At baseline, mean aerobic exercise frequency was 3.2 hours/week, other physical activity 9 MET-hours/week, and14% did some weight training, which increased to 29% by 2006. Weight training at least 150 minutes/week at baseline was associated with more aerobic exercise, less smoking, and a healthier diet. During 508,332 person-years of follow-up (18 years), 2,278 new cases of T2DM were documented. In multivariable-adjusted models, there was a dose-response relationship between an increasing amount of time spent on weight training or aerobic exercise and lower risk of T2DM (p < 0.001 for trend). Engaging in weight training or aerobic exercise for at least 150 minutes per week was independently associated with a 34% lower risk of T2DM (95% confidence interval [CI], 7%-54%) and 52% (95% CI, 45%-58%), respectively. Men who engaged in aerobic exercise and weight training for at least 150 minutes per week had the greatest reduction in T2DM risk (59%; 95% CI, 39%-73%).
The authors concluded that weight training was associated with a significantly lower risk of T2DM, independent of aerobic exercise. Combined weight training and aerobic exercise conferred a greater benefit.
Weight training is a good alternative for individuals who have musculoskeletal or other limitations for aerobic exercise. There was not a significant attenuation of the benefit for preventing T2DM with weight training after additional adjustment for BMI, but there was in men 65 years and with a family history of T2DM; findings that need to be clarified in studies appropriately powered. The decrease in T2DM with resistance training is thought to be related to the benefits of increasing muscle mass, which increases glucose utilization and insulin sensitivity. Further similar studies need to be done in cohorts with a higher risk for diabetes. While this study was limited to predominantly middle-aged white men, until there is evidence to the contrary, there is no reason to not make similar recommendations to other ethnic groups and women.
Keywords: Risk, Follow-Up Studies, Exercise, Insulin Resistance, Smoking, Primary Prevention, Glucose, Resistance Training, Body Mass Index, Middle Aged, Racquet Sports, Cardiovascular Diseases, Diet, Confidence Intervals, Diabetes Mellitus
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