Increased Muscular Strength Decreases Risk for Metabolic Syndrome

“In addition to improvements in skeletal muscle strength, endurance, power, and neuromuscular function, resistance exercise contributes to the prevention and management of atherosclerotic coronary heart disease, hypertension, diabetes, and overweight and mild obesity.”

Increased muscular strength is associated with a decreased risk for developing the metabolic syndrome, though perhaps not beyond that of cardiorespiratory fitness, according to the results of a prospective cohort study.

Radim Jurca, MD, from The Cooper Institute in Dallas, Texas, writes that, “Little is known, however, whether the health benefits of resistance exercise are independent of, or additive to, those already established for large muscle dynamic aerobic activity.”

Between 1980 and 2003, 3,233 men, aged 20 to 80 years, who were initially free of metabolic syndrome had 2 or more clinical examinations, including baseline muscular strength and cardiorespiratory fitness assessment. Muscular strength was quantified by combining body weight-adjusted 1-repetition maximal measures for leg and bench presses; and cardiorespiratory fitness was evaluated by maximal treadmill test. Mean duration of follow-up was 6.7 ± 5.2 years.

During follow-up, 480 men developed metabolic syndrome, defined on the basis of National Cholesterol Education Program–Adult Treatment Panel III criteria. Cox regression analysis adjusted for age revealed that the hazard ratios of metabolic syndrome associated with the incremental categories of muscular strength were 1.00 (referent), 0.88 (95% confidence interval [CI], 0.69 – 1.12), 0.77 (95% CI, 0.60 – 0.98), and 0.54 (95% CI, 0.42 – 0.71), respectively (P < .0001 for trend).

The inverse trend persisted even after adjusting for smoking, alcohol intake, number of baseline metabolic syndrome risk factors, family history of diabetes, hypertension, and premature coronary disease (P = .004), but it was weakened (P = .06) after further adjustment for cardiorespiratory fitness.

Compared with the lowest strength category, the highest strength category was associated with 44% and 39% lower risk (P < .05 each) of incident metabolic syndrome in men with normal weight (body mass index [BMI], <25 kg/m2) and overweight or obese men (BMI, >/=25 kg/m2), respectively. Incident rates were also inversely associated within age strata (20 – 39 years; P < .001; 40 - 49 years; P < .01; and >/=50 years; P < .05).

“Muscular strength was inversely associated with metabolic syndrome incidence, independent of age and body size,” the authors write. “Potential benefits of greater muscular strength presumably through resistance exercise training should be considered in primary prevention of metabolic syndrome.”

“Randomized controlled trials among diverse populations are needed to examine the possible role of resistance exercise training in preventing the development of metabolic syndrome and related disease outcomes,” the authors conclude. “Until such trials are completed, clinicians may wish to consider counseling their patients on the importance of aerobic physical activity and resistance exercise training for the primary prevention of metabolic disorders.”

Med Sci Sports Exerc. 2005;37:1849-1855