Isometric progressive resistive exercise for osteoporosis

To assess the effect of site-specific resistive isometric exercises on muscle strengthening of 10 muscle groups over 2 months. A second study measured bone alkaline phosphatase (ALP) as a marker of bone formation and bone resorption [urine deoxypyridinoline (D-Pyr) crosslinks] in a similar cohort.

Twenty postmenopausal Caucasian women aged 56 to 69 yrs (mean 61) on a stable or no medication regimen for the previous 6 months participated in the initial exercise cohort. Twenty-one women ages 52-69 (mean 62) participated in the second cohort. All women had osteopenia (DXA T less than -1.0) or osteoporosis (DXA T less than -2.5). An inflatable ball with attached nonelastic straps provided progressive resistance. Exercises consisted of a 5 s maximum contraction against progressively increasing resistance of the ball or nonelastic straps. Muscle strengthening was measured by a hand held dynamometer at 0, 4, and 8 weeks. Twenty women completed 8 weeks of the initial study and 21 women completed the second study.

Muscles showing increased strength in the first cohort were neck extensors (p < 0.04), hand grips (p < 0.02), elbow flexors (p < 0.05), quadriceps (p < 0.04), trunk extensors (p > 0.05, not significant = NS). Elbow extensors were purposely not exercised (as a control) and showed no significant strength increase. In the second cohort, increased muscle strength was measured in the neck extensors (p < 0.001), trunk extensors (p < 0.001), and left quadriceps (p < 0.024); and bone ALP increased (p < 0.05), with no change detected in bone resorption (urine D-Pyr).

Brief progressively resisted isometric exercises for 10 min daily are an adequate stimulus for muscle strengthening of the neck, back, upper and lower extremities, and are capable of enhancing bone formation measured by bone ALP.