The relationship between muscle quality and incidence of falls in older community-dwelling women: An 18-month follow-up study

Introduction: Important components that might mediate the relationship between aging and falls are reduced muscle strength and mass. Although muscle-related phenotypes have been linked to falls in older people, the role of muscle quality has yet to be examined. Aim: To investigate the relationship between muscle quality and incidence of falls over an 18-month follow-up in older community-dwelling women. Methods: A total of 167 women (68.1 +/- 6.2 years) underwent quadriceps isometric peak torque and thigh-muscle thickness assessments using isokinetic dynamometer and ultrasound, respectively. Muscle quality was considered as the ratio between maximal strength and muscle thickness. Participants were tracked by phone calls for ascertainment of falls during the follow-up period. Cox proportional regressions and X-2 tests were performed, with statistical significance set at P < 0.05. Results: A total of 139 volunteers were successful tracked over the follow-up period. The overall incidence of fall was 23.4% (95% CI: 16.5-31.0). Rate of fallers among individuals with low-muscle quality (57.7%) was higher than in those with normal muscle quality (15.3%) (X-2 = 21.132; P < 0.001). The proportion of multiple fallers was also significantly higher (X-2 = 11.029; P < 0.001) among volunteers with low-muscle quality when compared to those with normal muscle quality (14.8% and 3.6%, respectively). The presence of low-muscle quality was associated with a significantly greater risk of falls over the follow-up (hazard ratio: 4.619; 95% CI: 2.302-9.269). Conclusion: Low-muscle quality is associated with a higher incidence of falls in older women. These findings provide support for the concept that muscle quality is a clinically meaningful assessment among older people.