Neuromuscular Performance Among Covid-19 Survivors

Most individuals who contract SARS-CoV-2 recover. However, some report lingering fatigue and weakness, independent of the clinical symptoms during illness. PURPOSE: To examine differences in neuromuscular function between COVID-19 survivors and healthy young adults. METHODS: 12 healthy (24.4 ± 2.6 yrs) and 10 COVID-19 survivors (25.9 ± 1.7 yrs), 5.1 ± 3.8 months following contracting SARS-CoV-2. None of the survivors were hospitalized, but all reported various symptoms during and following illness. A subsample of 4 COVID-19 survivors reported systemic daily fatigue symptoms. Participants performed 5 s maximal isometric knee extensions (MVC), 10s submaximal contractions (25% and 70%MVC), and a fatiguing contraction (MVC to exhaustion). Volitional activation was determined during MVC, using the interpolated twitch technique. Bipolar electromyography (EMG) was used to characterize muscle activity. Muscle size was assessed using ultrasound. RESULTS: No differences were observed between healthy and COVID-19 groups in anthropometric measures, including quadriceps muscle depth (3.3 ± 0.8 and 3.4 ± 0.9 cm, respectively). There were no differences in muscle performance (peak torque: 2.3 ± 0.9 and 2.9 ± 1.0 Nm/kg, rate of torque development: 1211 ± 519 and 1249 ± 512 Nm/s, respectively), volitional activation (94.3 ± 4.8 and 95.6 ± 4.5%, respectively) and other neuromuscular measures (EMG amplitude, coactivation), between groups during MVC or submaximal contractions. During fatiguing contraction, the rate of perceived exertion and rate of torque reduction were not different between groups. However, among the subsample of survivors experiencing daily fatigue, the rate of torque reduction was significantly greater than healthy (0.84 ± 0.26 vs. 0.39 ± 0.10 %MVC/%time, respectively, p = .02). CONCLUSIONS: Past COVID-19 infection does not affect brief maximal and submaximal neuromuscular performance. However, prolonged contractions may be compromised among survivors who experience fatigue during daily life. Sandwich Scholarship, Haifa University