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

Tara-Lynne Rice ¹, Ingrid Chantler ¹ and Lisa C Loram ^1*

¹ University of the Witwatersrand, South Africa

^* To whom correspondence should be addressed. E-mail: lisa.loram{at}wits.ac.za.

Accepted 9 August 2007

Abstract

Objective: Inflammatory mediators, such as tumour necrosis factor alpha (TNF-), may contribute to delayed-onset muscle soreness. We assessed the effect of neutralizing TNF- with etanercept, a soluble TNF-receptor, on delayed-onset muscle soreness (DOMS) induced in the quadriceps muscle.

Design: On two separate occasions at least six weeks apart, we administered etanercept (25mg), or vehicle, subcutaneously, one hour before unaccustomed exercise to twelve healthy males in a randomised double-blind cross-over format. To induce DOMS, subjects completed four sets of 15 repetitions at 80% of their one repetition maximum (1 RM), using a 45° inclined leg press. Muscle soreness was assessed using a 100mm visual analogue scale (VAS), and pressure pain threshold (PPT) on the thigh before and 24h, 48h and 72h after exercise. Changes in the subject’s muscle strength were detected by remeasuring the subject’s 1RM 24h, 48h and 72h after exercise.

Results: Muscle strength decreased 24 and 48h after exercise regardless of agent administered (ANOVA, P<0.001). At 72h after exercise, muscle strength was significantly greater (P<0.01) after etanercept administration compared to placebo administration. The exercise protocol induced significant DOMS for up to 72h as reflected by reduced PPT and increased VAS scores (P<0.001). Etanercept had no effect on PPT or VAS.

Conclusion: TNF- does not affect muscle soreness associated with unaccustomed exercise, but may improve the recovery of muscle function.

Key Words: cytokine, eccentric exercise

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