Effects of neuromuscular electrical stimulation on cytokines in peripheral blood for healthy participants: a prospective, single-blinded Study

Introduction: The effect of exercise on cytokines may improve muscle strength. Neuromuscular electrical stimulation (NMES) is a muscle-preserving therapy that benefits patients unable to participate in active exercise. How NMES alters cytokines is unclear. The aim of this study was to study the effects of 1 NMES session on cytokines associated with protein metabolism during exercise. Methods: We evaluated the effects of NMES on IL-1, IL-6, IL-10 and TNF-α levels in peripheral blood. Participants received NMES to bilateral lower extremity muscles (quadriceps, tibialis anterior, gastrocnemius) for 30 min. Blood samples immediately pre- and post-NMES were drawn at 15-min intervals to 2-h follow-up, and the mean values of pre-NMES levels were compared to peak and trough post-NMES levels. For cytokines with significant changes, we conducted a repeated-measures linear regression analysis. We also measured post-NMES lactate and creatine kinase levels. Results: We enrolled nine eligible participants. There was a significant increase in peak IL-6 from the mean pre-NMES value [0·65 (0·89) to 1·04 (0·89) pg ml⁻¹, P = 0·001] and a significant decrease in trough IL-1 [0·08 (0·07) to 0·02 (0·02) pg ml⁻¹, P = 0·041] and TNF-α [2·42 (0·54) to 2·16 (0·59) pg ml⁻¹, P = 0·021]. In repeated-measures regression analysis, we identified significantly higher mean IL-6 values throughout the full 120 min post-NMES period, and a significantly higher mean IL-1 value at 30 min post-NMES. There were no significant differences in peak IL-10, trough IL-6, lactate, or creatine kinase values. Conclusions: In nine healthy humans, 30 min of NMES was temporally associated with changes in cytokines similar to the effects of active exercise and may mediate NMES' observed effects on reducing muscle weakness.