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.