Transcutaneous Electrical Nerve Stimulation for Muscle Recovery: Insights into Delayed Onset Muscle Soreness

Background: Delayed onset muscle soreness (DOMS) frequently occurs after engaging in strenuous physical activity. The manifestation of DOMS is often associated with changes in the biomechanical and viscoelastic characteristics of the affected muscles. Materials and Methods: Forty participants were enrolled and randomly assigned to two groups: the intervention group receiving transcutaneous electrical nerve stimulation (TENS, n = 20) and a control group (n = 20). A fatigue-inducing protocol targeting the gastrocnemius muscle was implemented to elicit DOMS. The effectiveness of TENS was assessed by evaluating alterations in the biomechanical and viscoelastic properties of the muscle. Pain intensity was recorded using the Numeric Rating Scale (NRS) at five time points: before the study began, three times during the intervention, and once at the conclusion of the study. Results: No statistically significant changes have been found regarding muscle tone (p = 0.162) and stiffness (p = 0.212) in Group 1. However, a statistically significant lower level of stiffness in Group 1 after the end of therapy has been detected (p = 0.008). Decrement values decreased statistically significantly, both in Group 1 (p = 0.015) and in Group 2 (p = 0.014). There were no statistically significant differences in decrement level between Group 1 and 2. Relaxation and creep decreased statistically insignificantly in both groups. At the end of the observation period (Day 4), statistically significant (p = 0.027) lower pain intensity was observed in Group 1. Conclusions: It has been demonstrated that TENS has had limited effectiveness in restoring baseline biomechanical and viscoelastic parameters of muscles that undergo changes during DOMS. TENS significantly relieves pain symptoms occurring in DOMS.