Comparing the effects of voluntary and electrically induced contractions on muscle recovery and vascular function

While both voluntary (VOL) and electrically stimulated (ES) contractions increase blood flow, ES induces greater oxidative stress, raising the risk of exercise induced muscle damage (EIMD), which can impair vascular function, and oxygen utilization.

We examined how ES and force-matched VOL contractions impact microvascular function and muscle oxidative capacity.

Utilizing a cross-over design, 16 healthy adults performed 40 isometric knee extensions (KE) via ES and VOL contractions. The following variables were assessed at baseline, 1 h, 24 h, and 48 h postexercise: knee extensor strength and soreness, microvascular function (hyperemic response to single passive leg movement (sPLM), and skeletal muscle oxidative capacity (SMOC) of the vastus lateralis.

Maximal voluntary contraction (MVC) was lower following ES than VOL at 24 h (324.7 ± 125.8 vs. 366.8 ± 125.6 N, p = 0.01) and 48 h (308.5 ± 124.7 vs. 379.0 ± 129.0 N, p = 0.001). Soreness (p ≤ 0.02) and muscle swelling (p ≤ 0.02) were greater after ES. Vascular function, quantified as the AUC for total hyperemic response following sPLM and measured by Doppler/ultrasound, was reduced following ES at 1 h (p = 0.01) and 24 h (p = 0.002). SMOC was more impaired after ES than VOL (p ≤ 0.03). There was a 31% decrease in oxygen recovery rate 1-h post-ES, with an additional 10% decline at 24-h and 48-h (p ≤ 0.03) compared to VOL.

ES seemed to elicit EIMD, resulting in reduced MVC, impaired recovery, while affecting microvascular function and oxidative capacity.