PHYSICAL-ACTIVITY, BUT NOT AEROBIC CAPACITY, CORRELATES WITH BACK STRENGTH IN HEALTHY PREMENOPAUSAL WOMEN FROM 29 TO 40 YEARS OF AGE

The correlation of muscle strength at various sites of the axial and a ppendicular skeleton with physical activity and aerobic capacity was a ssessed in women 29 to 40 years old. Muscle strength of the spine and upper extremities was determined with strain gauges in 96 healthy whit e women, and power grip was used as an indicator of upper extremity st rength. The physical activity score, which reflected the level of dail y weight-bearing activity and was based on a standardized scale, range d from 3 to 15. Maximal oxygen uptake (aerobic capacity) was measured in 69 of the 96 subjects. The mean values for maximal oxygen uptake we re 1.9 liters/min and 27.9 ml/kg per minute when normalized for weight . In general, muscle strength was significantly correlated between axi al and appendicular sites; thus, the axial musculature usually represe nts overall muscle strength. Maximal oxygen uptake in milliliters per kilogram per minute was not correlated with back extensor strength or upper extremity strength. Physical activity score was significantly co rrelated with back extensor strength but not with maximal oxygen uptak e (aerobic capacity) either in liters per minute or in milliliters per kilogram per minute. Thus, maximal oxygen uptake is an invalid marker for level of daily weight-bearing physical activity.