Muscle damage induced by neuromuscular electrical stimulation (NMES) with frequencies of 30 Hz and 100 Hz

Abstract

Neuromuscular electrical stimulation (NMES) is the action of therapeutic electrical stimulation on muscle tissue in order to contract the muscle and consequently improve the muscle status. Objective: To evaluate the muscle damage stemming from isometric muscle contraction induced by NMES of low frequency (30 Hz) and high frequency (100 Hz). Methods: Experimental crossover study, randomized, unblinded. The study included 10 male college students, age 24.4 ± 6.0 years, weight 77.1 ± 11.8 kg, height 176.1 ± 5.6 cm, and BMI of 24.8 ± 3 4 kg/m2. Two protocols (A) and (B) with an interval of 7 days between them. (A) - 20 minutes of NMES in the quadriceps at a frequency of 30 Hz (B) - 20 minutes of NMES at a frequency of 100 Hz. Measured lactate, creatine phosphokinase and lactate dehydrogenase before, immediately after, and 6 and 48 hours after the protocols. Results: Comparing 30 Hz vs. 100 Hz the following were observed: lactate (23.7 ± 6.7 vs. 13.4 ± 3.0 mg/dl, p = 0.001); CPK (195.4 ± 116.1 vs. 262.9 ± 153.6 IU, p = 0.022); LDH (374.3 ± 64 vs. 366.6 ± 84.1 IU, ns). The perception of contractile efficiency decreased significantly (p = 0.016) in the 100 Hz Protocol. Conclusion: Both the low-frequency NMES (30 Hz) and the high-frequency (100 Hz) elevate blood markers of muscle damage, most strikingly at the higher frequency. However, the achieved values reflect a normal response to a moderate-intensity exercise.