Background: To investigate the impact on bone and muscle of pathological conditions involving only one of the upper limbs, it is important to know the physiological differences due to the dominance effect.
Aim: To evaluate any physiological differences between dominant and non-dominant upper limbs in terms of bone mineral density (BMD), muscle mass, and muscle density at different levels.
Subjects and methods: The study considered 60 right-handed healthy adults, 30 men and 30 women. Cortical BMD, muscle area, and muscle density were investigated by pQCT-XCT-3000 Stratec at the proximal radius, trabecular and total BMD at the distal radius, and trabecular and cortical BMD at the second phalanx of the third finger. Hand grip strength was also measured.
Results: No significant differences in BMD were found between the dominant and non-dominant upper limbs at any of the sites considered, in men or women. Muscle density was also similar on the two sides, whereas muscle area at the proximal radius was significantly lower on the non-dominant side in both men [4177.5+/-475.1 vs 4009.3+/-552.7 mm2; Delta%: 4.1%; 95% confidence interval (CI) 1.7%-6.5%] and women (2903.9+/-470.9 vs 2720.3+/-411.7 mm2; Delta%: 6.1%; 95%CI 4.3%-7.9%). Hand grip strength proved greater on the right side in both men (48.5+/-8.8 vs 45.2+/-8.7 kg; Delta% 7.1; p<0.001) and women (29.1+/-4.3 vs 27.0+/-5.1 kg; Delta% 7.1; p<0.001).
Conclusion: The dominance effect does not seem to influence trabecular or cortical BMD at any of the sites in the upper limb. Muscle density is not modified by dominance, while muscle area is reduced on the non-dominant side and this should be borne in mind when the effect of pathological conditions on the body composition of a single forearm is investigated.