The role of inflammation in delayed muscle soreness (DMS) and the effects of indomethacin on DMS and perceived exertion

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Virginia Polytechnic Institute and State University

PART I: MARKERS OF INFLAMMATION IN DELAYED MUSCLE SORENESS Fifty-five untrained males were assigned to an experimental (E) or a control group (C), to re-examine the concept that DMS represents an acute inflammatory response. Subjects were assigned to receive either Indocin (Id; 100 mg per day) for 2 days prior to the treatment and a placebo (P) for 2 days after (Id-P); or the reverse combination (P-Id); or Id for- 4 days (Id-Id); or placebo (P-P). On the treatment day, to induce DMS, E subjects performed 30 min of bench-stepping with one leg leading throughout; C subjects rested for 30 min. Immediately before and after stepping/resting, all subjects used their right and left leg to perform 19 maximal and 15 submaximal repetitions on the Cybex II. Blood samples were collected -5 min before, immediately after bench stepping (0 h), 2 h after and 24, 48 and 72 h, to evaluate WBC. DMS was also monitored 0, 24, 48 and 72 h. All E subjects experienced a significant amount of DMS (p<.01) which peaked at 48 h after exercise (E=7.58 ± .79 vs 0 for C, X±SEM); however, no significant differences in soreness perception were observed between drug and placebo groups. Total WBC count ( cells/mm³ ) was significantly greater at 0 h (8,340±380) than at -5 min (6,699±365) for both E and C; this increase was most likely a response to Cybex exercise. At 2 h there was a significant increase in total WBC count for E ( 9,603±389) and no change for C ( 8,336±273}. Neutrophils increased significantly at 2 h for E only (6,428±375 vs 4,988±261 for C}. Bench-stepping leads to increases in DMS and increases in WBC count, particularly in neutrophils, 2 h after stepping; this data suggests that inflammation is involved in DMS.

PART II: EFFECT OF AN ASPIRIN-LIKE DRUG ON PERCEIVED EXERTION DURING BENCH STEPPING The object of this study was to determine whether perceived exertion (RPE) for the limb performing predominantly positive work was significantly greater than for the limb performing predominantly negative work, during 30 min of bench stepping. A second objective was to determine the effects of indomethacin (Id) on RPE. Thirty-nine males were randomly assigned to a drug (Id) or placebo (P) group and administered 150 mg indomechacin or placebo, beginning 36 h prior to stepping. Results indicated no significant differences between RPE for "concentric" and "eccentric" limbs of the P group inspite of the fact that the metabolic demand of the "concentric" limb was much greater. Indomethacin did not significantly alter RPE during stepping however, when RPE scores were totaled over the entire bench stepping period, the Id condition was associated with a greater (p < .01) psychological cost for the "concentric" leg effort as compared to P; this indicated that indomethacin might alter effort sense related to concentric contractions.