Relationship of muscle strength of back and upper extremity with level of physical activity in healthy women.

The objective of this study was to evaluate any correlation between the muscle strength of the upper extremity (appendicular muscles) and that of the back extensors (axial muscles) in postmenopausal women. Back extensor strength and power grip of the dominant hand were measured in 68 healthy postmenopausal women. The level of physical activity was determined according to a scale (score, 0-18) that considered vocational and avocational activities. Statistical analysis demonstrated a significant positive correlation between back extensor strength and power grip (r = 0.46, P less than 0.001) and back extensor strength and level of physical activity (r = 0.37, P less than 0.002). The correlation between level of physical activity and power grip was much less significant (r = 0.25, P less than 0.05) than that between physical activity and back strength. These data suggest that, in healthy individuals, stronger grip may also indicate stronger back extensor muscles. They also demonstrate that physical activity contributes significantly to the back extensor strength and, to a lesser degree, to the strength of the upper extremities.