Electrical stimulation to regain lower extremity muscle perfusion and endurance in patients with post-acute sequelae of SARS CoV-2: A randomized controlled trial.

Muscle deconditioning and impaired vascular function in the lower extremities (LE) are among the long-term symptoms experienced by COVID-19 patients with a history of severe illness. These symptoms are part of the post-acute sequelae of Sars-CoV-2 (PASC) and currently lack evidence-based treatment. To investigate the efficacy of lower extremity electrical stimulation (E-Stim) in addressing PASC-related muscle deconditioning, we conducted a double-blinded randomized controlled trial. Eighteen (n = 18) patients with LE muscle deconditioning were randomly assigned to either the intervention (IG) or the control (CG) group, resulting in 36 LE being assessed. Both groups received daily 1 h E-Stim on both gastrocnemius muscles for 4 weeks, with the device functional in the IG and nonfunctional in the CG. Changes in plantar oxyhemoglobin (OxyHb) and gastrocnemius muscle endurance (GNMe) in response to 4 weeks of daily 1 h E-Stim were assessed. At each study visit, outcomes were measured at onset (t 0 ), 60 min (t 60 ), and 10 min after E-Stim therapy (t 70 ) by recording ΔOxyHb with near-infrared spectroscopy. ΔGNMe was measured with surface electromyography at two time intervals: 0-5 min (Intv 1 ) and: 55-60 min (Intv 2 ). Baseline OxyHb decreased in both groups at t 60 (IG: p = 0.046; CG: p = 0.026) and t 70 (IG = p = 0.021; CG: p = 0.060) from t 0 . At 4 weeks, the IG's OxyHb increased from t 60 to t 70 (p < 0.001), while the CG's decreased (p = 0.003). The IG had higher ΔOxyHb values than the CG at t 70 (p = 0.004). Baseline GNMe did not increase in either group from Intv 1 to Intv 2 . At 4 weeks, the IG's GNMe increased (p = 0.031), whereas the CG did not change. There was a significant association between ΔOxyHb and ΔGNMe (r = 0.628, p = 0.003) at 4 weeks in the IG. In conclusion, E-Stim can improve muscle perfusion and muscle endurance in individuals with PASC experiencing LE muscle deconditioning.