Does trunk muscle mass measured by DXA reflect trunk muscular strength? — The International Society for the Study of the Lumbar Spine
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  3. Does trunk muscle mass measured by DXA reflect trunk muscular strength?

Does trunk muscle mass measured by DXA reflect trunk muscular strength? (#114)

Masaru Tanaka 1 2 , Masahiro Kanayama 1 , Fumihiro Oha 1 , Yukitoshi Shimamura 1 , Takeru Tsujimoto 1 , Yuichi Hasegawa 1 , Tomoyuki Hashimoto 1 , Hidetoshi Nojiri 3 , Muneaki Ishijima 3
  1. Spine Center, Hakodate Central General Hospital, Hakodate, Hokkaido, Japan
  2. Department of Orthopaedic Surgery, Juntendo Nerima Hospital, Nerima, Tokyo, Japan
  3. Department of Orhopaedic Surgery, Juntendo University, Bunkyo, Tokyo, Japan

INTRODUCTION

To date, it has been shown that muscle cross-sectional area is a major predictor of force production, while the relationship between muscular strength and muscle volume measured by whole-body dual-energy X-ray absorptiometry (DXA) was unclear. We investigated that the relation between DXA-derived regional muscle mass and muscular strength.

METHODS

A total of 48 healthy volunteers participated in this study. They were 22 men and 26 women with a mean age of 47.1±11.9 years, and underwent whole-body DXA and muscle strength measurements. Each part of the muscle mass was defined as the respective value of lean body mass measured by DXA. Each muscular strength was defined as the average value of three times measurements. We investigated (1) relation between upper limb muscle mass (ULM) and grip strength, (2) relation between lower limb muscle mass (LLM) and knee extensor/flexor strength, and (3) relation between trunk muscle mass (TM) and trunk extensor/flexor strength separately in men and women. In the region of upper and lower limbs, left and right mean values were compared respectively. Spearman's rank correlation coefficient was employed for statistical comparison, and P < 0.05 indicated statistical significance.

RESULTS

ULM was 2.65kg in men and 1.60kg in women. LLM was 8.17kg in men and 5.65kg in women. TM was 23.45kg in men and 18.14kg in women. Grip strength was 394N in men and 237N in women. Knee extensor strength was 508N in men and 308N in women. Knee flexor strength was 210N in men and 151N in women. Trunk extensor strength was 602N in men and 359N in women. Trunk flexor strength was 498N in men and 267N in women. ULM and grip strength were moderately correlated in men (r = 0.60, P < 0.0001), and strongly correlated in women (r = 0.76, P < 0.0001). LLM and knee extensor strength were weakly correlated in men (r = 0.43, P = 0.0038), and moderately correlated in women (r = 0.54, P < 0.0001). LLM and knee flexor strength were not correlated in men (r = 0.23, P = 0.1370), and weakly correlated in women (r = 0.39, P = 0.0047). There was no correlation between TM and trunk extensor strength both in men (r = -0.04, P = 0.8762) and women (r = 0.19, P = 0.3443). TM and trunk flexor strength were not correlated in men (r = 0.12, P = 0.6096), and weakly correlated in women (r = 0.44, P = 0.0232).

DISCUSSION

In the evaluation of DXA-derived regional muscle mass and muscular strength, correlation between ULM and grip strength, and correlation between LLM and knee extensor strength were statistically significant. Alternatively, TM and trunk extensor/flexor strength were not correlated except TM and trunk flexor strength in women. These data suggested that ULM was closely related to grip strength, and LLM was closely related to knee extensor strength, whereas TM was not related to trunk muscular strength. Additionally, higher correlation coefficients in women showed that DXA-derived muscle mass and correspondence muscular strength were more closely related in women.

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