Validity and feasibility of a seated push-up test to indicate skeletal muscle mass in well-functioning older adults

Introduction: Skeletal muscle mass (SMM) is a major component of the human body (> 30% of the body-weight) and plays crucial role in many bodily functions. However, SMM assessments require a complex and costly machine, which delays the ability to detect abnormalities related to SMM decline and, subsequently, reduces the effectiveness of the clinical management of older adults.

Purpose: This study aimed to: 1) assess the correlation between upper limb loading during a seated push-up test (ULL-SPUT) and SMM (concurrent validity); 2) compare the SMM of participants who passed and failed a seated push-up test (SPUT; discriminant validity); and 3) explore the ability of a failed SPUT to identify older individuals with low SMM.

Methods: Participants (n = 40, age approximately 73 years) were cross-sectionally assessed for their SMM using a portable bioelectrical impedance analysis, and SPUTs were evaluated using digital push-up loading devices that were the size of clinical push-up boards, in three starting positions: 1) high; 2) ring, and 3) long sitting positions.

Results: The ULL-SPUT, especially in a ring sitting position, was significantly correlated to SMM (r_s = 0.457-0.608, p < .005). The SMM and ULL-SPUT were significantly different between participants who passed and failed the SPUT (p < .05). Failure to complete the SPUT - that is, being unable to lift the body up from the floor during the test - showed an excellent ability to indicate participants with an SMM of < 28% of their body-weight (sensitivity > 83%, specificity > 82%, area under the curve = 0.93).

Conclusions: The inability to lift the body up from the floor during sitting using the upper limbs can be used as a screening tool to indicate those with low SMM. Such a simple screening measure may enhance the distribution of healthcare services across various community- and home-based settings, particularly during the coronavirus (COVID-19) pandemic, when hospital services are limited for many individuals, including older adults.