Integrated analysis of load-velocity profiles, muscle ultrasound measures, and lifestyle determinants in older adults with and without fall history.

Falls in older adults result from declines in muscle quality. This study aimed to examine differences in load-velocity profile (LVP) metrics, muscle ultrasound measures, strength, functional tests, and lifestyle between older adults with and without falls, and to analyze their association with sit-to-stand power. Sixty-two older adults (41 non-fallers, 21 fallers; mean age 68.32 ± 5.07 years) underwent three lab sessions. LVP was determined via functional electromechanical dynamometry during a loaded five times sit-to-stand test. Knee-extension, ankle-dorsiflexion, and handgrip strength were recorded. Functional capacity was assessed using the timed up and go test and the short physical performance battery. Tibialis anterior muscle thickness and echo intensity were measured via ultrasound. Lifestyle and quality of life were evaluated using questionnaires. Group differences were tested using t-tests or Mann-Whitney U tests; stepwise regression identified predictors of the area under the LVP, representing maximal mechanical power (Aₗᵢₙₑ). Non-fallers showed higher Aₗᵢₙₑ (p < 0.001; ES = 0.61) and L0, defined as the theoretical maximal load at zero velocity (p = 0.002; ES = 0.48), as well as greater knee-extension and handgrip strength (p = 0.001; ES = 0.50). Echo intensity was greater in fallers (p = 0.013; ES = 0.68), while muscle thickness did not differ (p = 0.073; ES = 0.49). Non-fallers scored higher in SF-36 physical functioning and pain, and WHOQOL-BREF physical health and psychological well-being (all p < 0.05). LVP derived from the loaded 5-STS discriminated fallers from non-fallers, with Aₗᵢₙₑ primarily associated with knee-extension strength and fall history.