Preconditioning by light-load eccentric exercise is equally effective as low-level laser therapy in attenuating exercise-induced muscle damage in collegiate men

BACKGROUND/OBJECTIVE: Previous studies have already reported an independent effect of light-load eccentric exercise (10% eccentric exercise contraction [EEC]) and low-level laser therapy (LLLT) as a protective measure against more strenuous eccentric exercise. However, the difference between these two interventions is largely unknown. Therefore, the present study aimed to compare the preconditioning effect of 10% EEC vs. LLLT on subjective, physiological, and biochemical markers of muscle damage in elbow flexors in collegiate men. METHODS: All 36 enrolled subjects were randomly assigned to either 10% EEC or LLLT group. Subjects in 10% EEC group performed 30 repetitions of an eccentric exercise with 10% maximal voluntary contraction strength 2 days prior to maximal eccentric exercise bout, whereas subjects in LLLT group were given LLLT. All the indirect markers of muscle damage were measured pre-exercise and at 24, 48, and 72 hours after the exercise-induced muscle damage protocol. RESULTS: The muscle soreness was reduced in both groups (p = 0.024); however, soreness was attenuated more in LLLT group at 48 hours (33.5 vs. 42.7, p = 0.004). There was no significant difference between the effect of 10% EEC and LLLT groups on other markers of muscle damage like a maximum voluntary isometric contraction (p = 0.47), range of motion (p = 0.16), upper arm circumference (p = 0.70), creatine kinase (p = 0.42), and lactate dehydrogenase (p = 0.08). Within-group analysis showed both interventions provided similar protection over time. CONCLUSION: This study indicated that light-load eccentric exercise confers similar protective effect against subsequent maximal eccentric exercise as LLLT. Both the treatments could be used reciprocally based on the patient preference, costs, and feasibility of the equipment.