Muscle strength and areal bone mineral density at the hip in women: a cross-sectional study.

Julie A Pasco,Sharon L Brennan-Olsen,Kara L Holloway,Mark A Kotowicz,David J Moloney

doi:10.1186/s12891-015-0586-2

Julie A Pasco, Sharon L Brennan-Olsen + Show 3 more

Open Access

https://doi.org/10.1186/s12891-015-0586-2

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Abstract

BackgroundMuscle strengthening exercises are promoted for building and maintaining a healthy skeleton. We aimed to investigate the relationship between muscle strength and areal bone mineral density (BMD) at the hip in women aged 26–97 years.MethodsThis cross-sectional study utilises data from 863 women assessed for the Geelong Osteoporosis Study. Measures of hip flexor and abductor strength were made using a hand-held dynamometer (Nicholas Manual Muscle Tester). The maximal measure from three trials on each leg was used for analyses. BMD was measured at the hip using dual energy x-ray absorptiometry (DXA; Lunar DPX-L). Total lean mass, body fat mass and appendicular lean mass were determined from whole body DXA scans. Linear regression techniques were used with muscle strength as the independent variable and BMD as the dependent variable. Models were adjusted for age and indices of body composition.ResultsMeasures of age-adjusted hip flexor strength and hip abductor strength were positively associated with total hip BMD. For each standard deviation (SD) increase in hip flexor strength, the increase in mean total hip BMD (SD) was 10.4 % (p = 0.009). A similar pattern was observed for hip abductor strength, with an increase in mean total hip BMD of 22.8 % (p = 0.025). All associations between hip muscle strength and total hip BMD were independent of height, but were nullified after adjusting for appendicular lean mass or total lean mass.ConclusionsThere was a positive association observed between muscle strength and BMD at the hip. However, this association was explained by measures of lean mass.

Highlights

Muscle strengthening exercises are promoted for building and maintaining a healthy skeleton
As a first step in exploring the muscle-bone relationship, we aimed to investigate the cross-sectional associations between hip flexor and hip abductor muscle strength and bone mineral density (BMD) at the total hip in women aged 26–97 years
Hip flexor strength was negatively correlated with age (r = −0.49, p < 0.001), positively with appendicular lean mass (r = +0.39, p < 0.001), total lean mass (r = +0.35, p < 0.001), body fat mass (r = +0.05, p = 0.132), hip abductor strength (r = +0.43, p < 0.001) and total hip BMD (r = +0.32, p < 0.001)

Summary

Introduction

Muscle strengthening exercises are promoted for building and maintaining a healthy skeleton. Meta-analyses reveal that a combination of high impact and high-magnitude loading exercises are most effective in enhancing areal bone mineral density (BMD) at the hip and spine in premenopausal women [5] and for reducing bone loss at these sites in postmenopausal women [6]. Such reviews provide evidence that regular weight bearing activities and muscle strengthening exercises have beneficial skeletal effects but what remains uncertain is whether it is an improvement in muscle strength or muscle mass that impacts on bone. As a first step in exploring the muscle-bone relationship, we aimed to investigate the cross-sectional associations between hip flexor and hip abductor muscle strength and BMD at the total hip in women aged 26–97 years

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