Maximum grip strength is not related to bone mineral density of the proximal femur in older adults

In the past decade there have been numerous publications reporting a signif icant and direct relationship between handgrip strength and bone mineral de nsity (BMD) of the proximal femur in older adults. The present report chall enges the appropriateness of the methods, and thus the conclusions used in these studies. Specifically, these studies failed to control for the concom itant influence of body weight on both BMD and muscle strength. In the pres ent study, maximum handgrip strength was measured using a conventional hand -held hydraulic dynamometer. Bone mineral density of the proximal femur was measured using dual-energy X-ray absorptiometry (DXA). Using allometric sc aling, the influence of body weight on the value of maximum handgrip streng th was removed for the data of the women. A small, but significant relation ship between BMD of the proximal femur and maximum handgrip strength was fo und that accounted for about 6% of the total variation. The relationship be tween BMD of the proximal femur and unscaled maximum handgrip strength was not significant for the men. The findings diminish the confidence in a prot ective effect of skeletal muscle on some nonadjacent skeletal structures an d suggest that these relationships may benefit from being revisited. The re sults highlight the utility of allometric scaling in analyses in which the relationship between a physiological variable and a body dimension variable can be nonlinearly and simultaneously influenced by other body dimension v ariables that are not considered in the analysis and therefore are statisti cally uncontrolled.