Muscle quality, muscle mass, muscle strength, and pulse wave velocity between healthy young and elderly adults

Although maintaining an optimal level of muscle quality in older persons is necessary to prevent falls and disability, there has been limited research on muscle quality across age and gender groups. The associations of muscle quality, muscle strength, and muscle mass also remain less explored. Purpose: This study examined the muscle quality differences (arm and leg) between healthy young and elderly adults across gender groups. This study also examined the associations of muscle quality, muscle strength, and muscle mass in young and elderly adults, respectively. Methods: Seventy-one total subjects were recruited for this study within age groups 20-29 years old (20 females and 20 males) and 60-80 years old (18 females and 13 males). All participants completed anthropometric measures, dual-energy x-ray absorptiometry, pulse wave velocity, handgrip strength and leg strength tests, gait speed, and sit to stand test. Results: Young male adults had a greater leg muscle quality index (leg MQI) than did elderly male adults (21.8 Nm/kg vs. 16.3 Nm/kg, p = 0.001). Similarly, young female adults had a greater leg MQI than did old female adults (21.3 Nm/kg and 15.6 Nm/kg, p<0.001). For arm muscle quality index (arm MQI), there was a gender difference in young adults (p = 0.001), but not for the elderly adults. Among elderly adults, there was a positive association between leg MQI and isometric leg strength (r = 0.79, p<0.001). Notably, there was a negative association between leg MQI and leg lean mass (r = -0.70, p<0.001) and between arm MQI and arm lean mass (r = -0.58, p = 0.001). In young adults, there was also a positive association between arm MQI and handgrip strength (r = 0.53, p<0.001) and between leg MQI and isometric leg strength (r = 0.81, p<0.001). There was no association between muscle quality and muscle mass in young adults. Conclusion: Young adults had a greater leg muscle quality than did elderly adults in both men and women. Leg muscle quality is positively associated with leg muscle strength in both young and elderly adults but is inversely associated with leg muscle mass in the elderly adults.