Static one-leg standing balance test as a screening tool for low muscle mass in healthy elderly women

Identification of simple screening tools for detecting lower skeletal muscle mass may be beneficial for planning effective interventions in the elderly.

We aimed to (1) establish a threshold for one-leg standing balance test (OLST) time for low muscle mass, and (2) test the ability of that threshold to assess muscular impairments in a poor balance group.

Eyes-open OLST (maximum duration 30 s) was performed with right and left legs in 291 women (age 71 ± 6 years). OLST time was calculated as the sum of the OLST time of right and left legs. Fat-free mass (FFM), skeletal muscle mass (SMM), fat mass, biceps brachii and vastus lateralis sizes; handgrip strength (HGS), elbow flexion maximum torque (MVC_EF) and knee extension maximum torque (MVC_KE) were measured. Muscle quality was calculated as MVC_KE/FFM and physical activity was assessed by questionnaire. Low muscle mass was defined as SMM_relative of 22.1%, a previously established threshold for pre-sarcopenia.

The OLST threshold time to detect low muscle mass was 55 s (sensitivity: 0.63; specificity: 0.60). The poor balance group (OLST < 55 s) had higher fat mass (3.0%, p < 0.001), larger VL thickness (5.1%, p = 0.016), and lower HGS (- 10.2%, p < 0.001), MVC_EF (- 8.2%, p = 0.003), MVC_KE (- 9.5%, p = 0.012), MVC_KE/FFM (- 11.0%, p = 0.004) and physical activity (- 8.0%, p = 0.024) compared to the normal balance group. While after adjusting age, the differences exist for HGS, fat mass and VL thickness only.

An OLST threshold of 55 s calculated as the summed score from both legs discriminated pre-sarcopenic characteristics among active, community-dwelling older women with limited potential (sensitivity 0.63, specificity 0.60).

OLST, which can be performed easily in community settings without the need for more complex muscle mass measurement, may help identify women at risk of developing sarcopenia.