Effects of Neuromuscular Electrical Stimulation on Cramp Threshold Frequency and Pain in Adults with Nocturnal Leg Cramps: An EMG-Based Assessment: Randomized Controlled Trial

Background: Muscle cramps are sudden, painful, and recurrent contractions that may interfere with physical activity and daily life. Although stretching is commonly used to relieve cramps, the effectiveness of neuromuscular electrical stimulation (NMES) has not been fully established. Objective: This study aimed to investigate the effects of NMES on cramp threshold frequency (CTF) and pain intensity in individuals with a history of nocturnal leg cramps without identifiable underlying disorders. Methods: Twenty healthy adults with a history of leg cramps were randomly assigned to either an experimental group (n = 10) or a control group (n = 10). The experimental group received electrical stimulation to both calves using an NMES device, whereas the control group performed lower-extremity static stretching exercises. Both groups participated in an intervention program conducted three times per week for 20 min per session over 4 weeks. CTF was measured using surface electromyography, and muscle cramps were induced using an electrical stimulation device starting at 4 Hz, with the frequency increased by 2 Hz after each stimulation set until cramp onset. Pain intensity was assessed using the Visual Analog Scale (VAS). Within-group and between-group comparisons before and after the intervention were analyzed using paired-samples t-tests and independent-samples t-tests, respectively, with the level of statistical significance set at p < 0.05. Results: Both groups showed significant improvements in CTF and pain intensity after the intervention. However, the NMES group demonstrated significantly greater improvement than the stretching group. The increase in CTF was significantly greater in the experimental group than in the control group (9.20 ± 6.75 vs. 1.80 ± 1.75; t = 3.357, p = 0.007). Likewise, the reduction in VAS score was significantly greater in the experimental group than in the control group (−5.20 ± 0.92 vs. −1.60 ± 0.84; t = 9.128, p < 0.001). Conclusions: NMES may be an effective intervention for increasing cramp threshold frequency and reducing pain in individuals with leg cramps, with greater benefits than lower extremity stretching.