Piroxicam fails to reduce myocellular enzyme leakage and delayed onset muscle soreness induced by isokinetic eccentric exercise

To test the hypothesis that delayed onset muscular soreness (DOMS) following intense eccentric muscle contraction could be due to increased production of prostaglandin E2 (PGE2), ten healthy male subjects were studied. Using a double-blind randomized crossover design, each subject performed two isokinetic tests separated by a period of at least 6 weeks: once with placebo, and once with piroxicam (Feldene®). They were given one capsule containing either placebo or piroxicam (20 mg) per day for 6 days with initial doses given starting 3 days prior to isokinetic testing. Exercise consisted of eight stages of five maximal contractions of the knee extensor and flexor muscle groups of both legs separated by 1 min rest phases, on a Kin Trex device at 60°/s angular velocity. The subjective presence and intensity of DOMS were evaluated using a visual analogue scale immediately after, and 24 and 48 h after each test. The mean plasma concentration of PGE2 measured at rest and after exercise was significantly lower in the group treated with piroxicam (p < 0.05). However, statistical analysis (two-way ANOVA test) revealed that exercise did not cause any significant change of mean plasma PGE2 over time in either of the two groups. Eccentric work was followed by severe muscle pain in extensor and flexor muscle groups. Maximal soreness was noted 48 h postexercise. Serum creatine kinase activity and the serum concentration of myoglobin increased significantly, and reached peak values 48 h after exercise in both experimental conditions (p < 0.001). By paired t-test, it appeared that there were no significant differences in the serum levels of these two markers of muscle damage between the two groups at any time point. We conclude that: (1) oral administration of piroxicam fails to reduce muscle damage and DOMS caused by strenuous eccentric exercise; and (2) the hypothetical role of increased PGE2 production in eccentric exercise-induced muscle damage, DOMS, and reduced isokinetic performance is not substantiated by the present results.

To test the hypothesis that delayed onset muscular soreness (DOMS) following intense eccentric muscle contraction could be due to increased production of prostaglandin E2 (PGE2), ten healthy male subjects were studied. Using a double-blind randomized crossover design, each subject performed two isokinetic tests separated by a period of at least 6 weeks: once with placebo, and once with piroxicam (Feldene(R)).
They were given one capsule containing either placebo or piroxicam (20 mg) per day for 6 days with initial doses given starting 3 days prior to isokinetic testing. Exercise consisted of eight stages of five maximal contractions of the knee extensor and flexor muscle groups of both legs separated by 1 min rest phases, on a Kin Trex device at 60/s angular velocity. The subjective presence and intensity of DOMS were evaluated using a visual analogue scale immediately after, and 24 and 48 h after each test. The mean plasma concentration of PGE2 measured at rest and after exercise was significantly lower in the group treated with piroxicam (p < 0.05). However, statistical analysis (two-way ANOVA test) revealed that exercise did not cause any significant change of mean plasma PGE2 over time in either of the two groups. Eccentric work was followed by severe muscle pain in extensor and flexor muscle groups. Maximal soreness was noted 48 h postexercise. Serum creatine kinase activity and the serum concentration of myoglobin increased significantly, and reached peak values 48 h after exercise in both experimental conditions (p < 0.001). By paired t-test, it appeared that there were no significant differences in the serum levels of these two markers of muscle damage between the two groups at any time point. We conclude that: (1) oral administration of piroxicam fails to reduce muscle damage and DOMS caused by strenuous eccentric exercise; and (2) the hypothetical role of increased PGE2 production in eccentric exercise-induced muscle damage, DOMS, and reduced isokinetic performance is not substantiated by the present results.
Key words: Delayed onset muscle soreness, Eccentric contraction, Isokinetic exercise, Muscle damage, Non-steroidal anti-inflammatory agent, Prostaglandin Piroxicam fails to reduce myocellular enzyme leakage and delayed onset muscle soreness induced by isokinetic eccentric exercise J-L. Croisier, G. Caius, 2"4"CA T. Monfils, 1"4 G. Deby-Dupon, 2"3 M. Fafchamps, I. Venneman, 3 J-M. Crielaard, A. Juchms-Ferir, s C. Lhermerout, 4 M. Lamy 2"3 and C. Deby 2 Introduction Delayed onset muscle soreness (DOMS) refers to a dull, aching pain, frequently combined with tenderness and stiffness, localized to groups of previously active muscles. These symptoms are usually observed following strenuous, unaccustomed exercise, especially when eccentric contractions are involved. '2 DOMS sensations develop in the first 24 h following muscular work and subside within 5 to 7 days after exercise. 230 Mediators of Inflammation Vol 5 1996 Despite the volume of data that have accumulated concerning DOMS during the last decade, the underlying mechanisms of this phenomenon remain poorly understood. Based on previous studies showing that strenuous exercise causes muscle and connective tissue damage, as well as an inflammatory response involving the release of algogenic inflammatory mediators such as prostaglandins (PG), 4-7 it has been hypothesized that increased PG production by activated macrophages in injured areas could be one of the main chemical stimuli responsible for DOMS. 8 Histological and biochemical indices of exercise-induced muscle damage, [9][10][11][12][13][14][15][16] the presence of leucocytes capable of producing arachidonic acid (AA) derived products in damaged muscles, 4'5'7 and the increased production of these substances during exercise 4-7 support this hypothesis. The results of a recent human study, where ibuprofen, a potent nonsteroidal anti-inflammatory drug (NSAID), reduced both DOMS and the decrease of muscle performance after strenuous eccentric contractions 18 argued also for the involvement of PGs. It should be pointed out, however, that the effects of inhibitors of AA metabolism on DOMS is a matter of controversy. Several research groups have reported that anti-inflammatory agents inhibiting the production of AA-derived compounds failed to alleviate soreness after exercise. '9'2 Among the possible factors responsible for these discrepancies are the administration protocol of NSAIDs and the effective doses that are absorbed. Therefore, in an attempt to address the question of whether metabolites of AA derived from the cyclooxygenase pathway, especially PGE2, are involved in DOMS, we studied the effects of piroxicam (Feldene(R)), another potent NSAID, on perceived soreness, biochemical indices of muscle damage, and plasma levels of PGE2 in subjects submitted to maximal eccentric isokinetic contractions. To optimize the potential effects of piroxicam on these variables, the drug was administered both before (prophylactically) and after (therapeutically) to each subject.

Methods
Subjects.. Ten moderately active, healthy male subjects volunteered to take part in this study after giving informed consent. Their mean age (+ S.E.M.) and body mass were 22 4-0.4 years and 74 1.5 kg, respectively. None was currently involved in lower body resistance or endurance training. They were requested to refrain from strenuous exercise and to abstain from the consumption of any form of medication during the study period. The experimental protocol was approved by the Ethics Committee of the University Hospital Center of Liege. jects were familiarized with the experimental procedures and possible risks involved. They were accustomed to the isokinetic device by performing 10 to 20 submaximal eccentric contractions of quadriceps and hamstring muscles. On their second visit, the eccentric and concentric maximum peak torque (PTmax) of the knee flexor and extensor muscle groups were measured bilaterally as follows. Standard warm-up exercises consisted of 5 min cycling at 75-100 W on a bicycle ergometer (60 rpm) and stretching of the muscle groups subsequendy used for isokinetic contractions. This warm-up protocol was systematically applied before each isokinetic trial. After a 5 min recovery phase, the subjects performed three maximal contractions of knee flexor and extensor muscles at 60/s in the eccentric mode. The greatest peak torque values were taken to represent PTmax. At least 2 weeks after this first test, the volunteers were randomly divided into two groups of five subjects who were given six capsules containing either 20 mg of piroxicam or a placebo. Using a double-blind procedure in which neither the subjects nor the investigator providing the capsules were aware of the subjects assigned group, the volunteers were instructed to take one capsule per day, starting 3 days before the isokinetic sessions. Each subject served as his own control, and completed two study protocols separated by at least 6 weeks: once with placebo and once with piroxicam. Exercise consisted of eight stages of five maximal contractions of the knee extensor and flexor muscle groups of both legs, separated by 1 min rest phases. To assess the effects of isokinetic contractions on muscle function, PTmax was measured on day two after exercise testing, using the protocol described above.
Perception of muscle soreness and indirect evaluation of muscle damage: The subjective presence and intensity of DOMS were evaluated using a visual analogue scale graded from 0 (no pain) to 10 (very severe, intolerable pain) immediately after, and 24 and 48h after eccentric testing.
Increased serum levels of creatine kinase (CK) and myoglobin (Mb) were used as indirect indices of exercise-induced muscle damage. Experimental procedures.. All isokinetic measurements were performed on a Kin Trex device (Meditronic Instruments SA, Ecublens, Switzerland) at 60/s angular velocity. During these experiments, the subjects performed isokinetic exercise in a seated position at approximately 105 of hip flexion. Belts placed across hips, chest and thigh were used to stabilize their position.
On their first visit to the laboratory, the sub-Blood sampling: Before each test, an indwelling catheter was inserted into an antecubital vein and sealed. Venous blood samples (10 ml) were collected into sterile tubes immediately before isokinetic test, 10 min after catheter insertion; immediately after exercise, and after 30 min recovery. Two additional blood samples were taken by venipuncture 24 and 48 h after exercise, respectively. The venous blood samples were J-L. Croisier et al. divided in two aliquots: 5 ml whole fresh blood 400 into a plain plastic tube, and 5 ml of whole blood into a vial containing EDTA as anticoagulant. The first portion was allowed to clot a00 at room temperature, and the serum phase was used for the measurement of creatine kinase z (CK) activity and myoglobin (Mb) concentration.
The second portion was immediately centrifuged.

Results
Mean peak torque produced by the quadriceps and hamstring muscle groups during pre-and post-test exercise sessions in the two experimental conditions are shown in Fig. 1. Pre-test mean PTmax of knee flexor and extensor muscle groups were 157 4-9 and 339 _ _ _ 17 Nm, respectively. Maximum eccentric contractions were not followed by any significant change of this variable after two days of recovery.
As shown in Fig. 2 Fig. 3. When compared to the ery (p < 0.001). Serum Mb concentration also placebo group, this variable was significantly demonstrated a delayed peak after 48 h recovery decreased at four time points in the piroxicam in both experimental conditions (p < 0.001). group (p < 0.05). By the two-way ANOVA test, it Piroxicam did not significantly change the mean appeared that exercise did not cause any sig-serum levels of these biochemical markers of nificant change of plasma PGE2 concentration muscle damage at any time point. over time in either experimental condition.
The effects of exercise on serum levels of CK Discussion and Mb are shown in Fig. 4 and 5, respectively. Beginning on the day after the isokinetic test, The marked increase of serum CK activity and marked release of CK was observed in both Mb concentration following isokinetic eccentric Piroxicam and delayed muscle soreness suggesting that other factors could also be involved in exercise-induced pain, as well as the exercise is in agreement with the results of prediscrepancies concerning the effects of drugs vious studies. 1'3'1'15'18'21 This protein leakage known to inhibit the AA metabolism on DOMS from skeletal muscle has been widely used to led us to verify whether piroxicam could effecestimate the severity of exercise-induced skeletal tively help to manage pain, reduced muscle permuscle damage. In accordance with this view, the formance and muscle damage following maximal data presented in Figs 4 and 5 indicate that the isokinetic contractions in the eccentric mode. To present exercise protocol caused severe myooptimize the inhibitory action of this agent on cellular injury. Surprisingly, when compared to PGE2 synthesis, six doses of 20 mg piroxicams the PTmax measured before isokinetic exercise, daily, with initial dose given 3 days before the the ability of the knee flexor and extensor exercise tests were administered. The significant muscle groups to produce force was unaffected reduction of plasma PGE2 concentrations 2 days after the damage induced by the two demonstrates the efficacy of cyclooxygenase experimental conditions. This suggests that blockade. However, piroxicam administered had muscle injury was not severe enough to .alter no effect on muscle enzyme leakage and DOMS PTmax and/or that motor units containing non-following isokinetic eccentric contractions. These damage fibres were recruited, findings lead us to conclude that PGE2 (and Despite the large number of studies currently probably other compounds) derived from AA J-L. Croisier et al. metabolism via the cyclooxygenase pathway do not play a major role in the pathogenesis of DOMS nor in exercise-induced damage. Nevertheless, the hypothesis that larger doses of piroxicam or lowering the plasma levels of PGE2 below 200 pg/ml could reduce DOMS in subjects submitted to damaging exercise of longer duration deserves to be tested experimentally.
In contrast with previous studies where strenuous exercise was found to increase plasma and muscle levels of AA-derived prodcuts, 4-7 there was no significant change in plasma PGE2 concentration over time in the two experimental conditions. The reasons for this discrepancy are unclear. One possibility is that we measured plasma levels of PGE2 in venous blood samples drawn at a site distant from the active muscles in which this compound has been shown to accumulate. 7 Because of the short half-life of PGE2 in blood, it is possible that regional changes of this variable in the venous effluent of skeletal muscles are not detectable in blood from a forearm vein. Another factor that could act in concert with the sampling site effects is the limited muscle mass involved in the isokinetic exercise. The isokinetic device used in the present study does not allow simultaneous contraction of limb muscles on both sides. It is therefore possible that the amount of PGE2 released from the active muscles was too low to be reflected by changes in venous PGE2 concentrations measured in blood samples drawn from a forearm vein. For ethical and technical reasons, we did not measure the arterio-venous difference of PGE2 at the lower limbs. Therefore, increased production of this compound induced by exercise in the active muscles cannot be deftnitively ruled out. Nevertheless, the significant difference of resting and post-exercise plasma concentrations of PGE2 between the two groups demonstrates that the dose of piroxicam used in this study effectively inhibited the production of this compound. As mentioned above, because the failure to find a significant difference in either the serum levels of the biochemical markers of muscle injury or in the intensity of DOMS between the two groups, despite piroxicam-induced reduction of plasma PGE2 concentrations, argues against the hypothesis that cyclooxygenase-derived AA metabolism are involved in exercise-induced damage and DOMS. Based on these results, it would appear that the activation of pain afferents after eccentric contractions is caused by other noxious stimuli. It has been suggested that increased intramuscular pressure, 2 and/or production of algogenic substances such as serotonin, histamine, acetylcholine and kinins could be involved in the production of DOMS. To our knowledge, these hypotheses remain to be tested experimentally.