Reply to the Letter “Disputing the use of static one-leg standing balance test for screening low muscle mass”

Abstract

To the editor, We thank Dr. Razaq and co-authors for their interest and commentary on the use of a one leg standing balance test (OLST) for assessing lower muscle mass and thus screening potential risk of future sarcopenia among elderly women in our recently published paper [1]. Overall, we agree with the sentiment of their commentary that is to recommend the use of a combination of functional tests [e.g. chair stand test (CST) and handgrip strength (HGS)] and thigh muscle mass using ultrasonography to confirm diagnosis of sarcopenia [2]. Indeed, their comments regarding the suitability of lower limbs assessments for identifying a meaningful impact of ageing atrophy are without question [3]. In contrast however, we sought to identify a threshold time for an OLST which corresponds with the current sarcopenia guidelines that are based on a whole-body assessment of muscle mass [4]. Consistent with other “functional” tasks that have been used for assessing the impact of ageing muscle loss, including CST and HGS, we add to the identified OLST thresholds for locomotive syndrome [5], and showed that OLST could be incorporated into the assessment toolkit currently adopted to identify elderly women at risk of low muscle mass. Indeed, we observed in our data that those individuals with poor balance also had low handgrip, and weaker knee extension. Interestingly, we observed a thicker thigh muscle in the poor balance group, a likely consequence of higher muscle adiposity with ageing, and a limitation to the measurement of thigh muscle circumference proposed as an alternative by the authors. All assessment tools are proposed with inherent limitations, as Dr Razaq notes balance tests are likely to be influenced by the comorbidities. Poor balance has been previously associated with parameters that could highly affect an individual’s independence such as risk of injurious falls [6], functional status [7], and locomotive syndrome [5]. Our findings are presented with the constraints of the exclusion criteria that are adopted and acknowledge that a 55 s OLST may not be reached by elderly women with a healthy muscle mass but with a pre-existing vestibular condition. Regardless, a normative value for healthy elderly women for combined OLST, provides a simple benchmark against which others can be compared, below which further assessment is needed, thus forming the basis of an initial screening tool for ageing muscle mass and health, that would complement the physiological parameters identified by Dr Razaq’s CST. In addition to HGS and CST, Dr. Razaq emphasised that the measurement of lower limb muscle size by ultrasonography, could be better screening tool for lower muscle mass than OLST. We agree completely and have adopted this within numerous of our own studies. We believe however, that it may not be readily available in community settings due to its cost and requirement of trained personnel for early screening programme. Therefore, the use of balance test may be advantageous, which does not require any sophisticated equipment other than a stopwatch, and therefore, individuals can track their performance easily in the community or residential settings. Collectively, with the observations in our published paper [1] and previous literature suggesting poor balance associations with worse muscle phenotypes, the simplicity of the OLST, without the requirement of any specialised equipment, we suggest OLST as screening tool to identify risk population whilst acknowledging Dr. Razaq suggestions that alternatives tests are available for assessing the ageing decline in muscle mass and function. * Praval Khanal [email protected]