Muscle strength and equilibrium-maintaining ability in post-COVID women

Abstract

The WHO declared COVID-19 a global pandemic [1], but the long-term consequences and aftermath of the disease remain unclear. The SARS-CoV-2 virus infects the respiratory system and probably also affects many other systems, including the musculoskeletal system [2–4]. In clinical practice, it has been observed that after recovering from COVID-19, a large number of seniors report prolonged general weakness and muscle fatigue. Falls, for instance, are a well-known consequence of reduced muscle strength [5,6]. Is COVID-19 infection associated with long-term reductions in muscle strength and balance ability in older women? The Study Group included 25 women, aged 65+, who declared they had recovered from SARS-CoV-2 infection. The Control Group consisted of women (n=30) of similar age, tested prior to the SARS-CoV-2 pandemic. Muscle torques were measured for the knee flexors (KF), knee extensors (KE), trunk flexors (TF), trunk extensors (TE), and elbow flexors (EF) under isometric conditions using a JBA Staniak® isometric torquemeter, by the maximum voluntary contraction method. Balance was assessed using a Biodex Balance System SD (BBS) platform. A static Postural Stability Test (PST) was performed using the stability platform with eyes open and eyes closed. A dynamic Fall Risk Test (FRT) was performed with eyes open at various levels of platform instability, and on this basis a fall risk index (FRI 6-2) was determined for each subject. Differences between the groups were assessed using the Mann-Whitney U test. A significance level of α=0.05 was assumed. Muscle torque values were normalized to the body weight of each subject. Statistical analysis showed higher values of EF, TF and TE for the Control Group. No statistical differences were found in static stabilographic parameters between groups. The Post-COVID Group did show higher results of the dynamic stabilographic index (FRI6-2) compared to the Control Group, which is indicative of poorer balance abilities. Results are presented in Table 1. Table 1 The results of the muscle toques of various muscle groups and fall risk in Post-COVID Group and Control GroupDownload : Download high-res image (88KB)Download : Download full-size image EF– elbow flexors torque; KF– knee flexors torque; KE– knee extensor torque; TF– trunk flexors torque; TE– trunk extensors torque; FRI– fall risk index; *n=24 We found FRI6-2 to be correlated with TE (r= -0.38) and TF (r= -0.37) for all participants, but this correlation was larger in the Post-COVID Group (r= -0.68 for TE and r= -0.55 for TF). Results indicate that post-COVID women exhibit impaired strength of various muscle groups and body balance in dynamic conditions. Post-COVID physiotherapy should therefore take into account not only respiratory problems but also musculoskeletal and equilibrium disorders, e.g. by using resistance training to improve muscle strength.