Neutralisation of muscle tumour necrosis factor alpha does not attenuate exercise-induced muscle pain but does improve muscle strength in healthy male volunteers

Objective: Inflammatory mediators, such as tumour necrosis factor alpha (TNF alpha), may contribute to delayed-onset muscle soreness. The effect of neutralising TNFa with etanercept, a soluble TNF alpha receptor, on delayed-onset muscle soreness (DOMS) induced in the quadriceps muscle was analysed. Design: On two separate occasions at least 6 weeks apart, etanercept 25 mg or vehicle was given subcutaneously 1 hour before unaccustomed exercise to 12 healthy men in a randomised double-blind cross-over format. To induce DOMS, subjects completed 4 sets of 15 repetitions at 80% of their one-repetition maximum (1RM), using a 45u inclined leg press. Muscle soreness was assessed using a 100-mm visual analogue scale (VAS), and pressure pain threshold (PPT) on the thigh before and 24, 48 and 72 hours after exercise. Changes in the subject's muscle strength were detected by reassessing the subject's 1RM 24, 48 and 72 hours after exercise. Results: Muscle strength decreased 24 and 48 hours after exercise regardless of agent administered (analysis of variance, p<0.001). At 72 hours after exercise, muscle strength was significantly greater (p<0.01) after etanercept than after placebo. The exercise protocol induced significant DOMS for up to 72 hours, as reflected by reduced PPT and increased VAS scores (p<0.001). Etanercept had no effect on PPT or VAS. Conclusion: TNF alpha does not affect muscle soreness associated with unaccustomed exercise, but may improve the recovery of muscle function.