Myocellular enzyme leakage, polymorphonuclear neutrophil activation and delayed onset muscle soreness induced by isokinetic eccentric exercise.

To address the question of whether delayed onset muscular soreness (DOMS) following intense eccentric muscle contraction could be due to increased production of the arachidonic acid derived product prostaglandin E2 (PGE2). 10 healthy male subjects were submitted to eccentric and concentric isokinetic exercises on a Kin Trex device at 60 degrees/s angular velocity. Exercise consisted of 8 stages of 5 maximal contractions of the knee extensor and flexor muscle groups of both legs separated by 1 min rest phases. There was an interval of at least 30 days between eccentric and concentric testing, and the order of the two exercise sessions was randomly assigned. The subjective presence and intensity of DOMS was evaluated using a visual analogue scale, immediately, following 24 h and 48 h after each test. Five blood samples were drawn from an antecubital vein: at rest before exercise, immediately after, after 30 min recovery, 24 h and 48 h after the tests. The magnitude of the acute inflammatory response to exercise was assessed by measuring plasma levels of polymorphonuclear elastase ([EL]), myeloperoxidase ([MPO]) and PGE2 ([PGE2]). Using two way analysis of variance, it appeared that only eccentric exercise significantly increased [EL] and DOMS, especially of the hamstring muscles. Furthermore, a significant decrease in eccentric peak torque of this muscle group only was observed on day 2 after eccentric work (- 21%; P < 0.002). Serum activity of creatine kinase and serum concentration of myoglobin increased significantly 24 and 48 h after both exercise tests. However, these variables reached significantly higher values following eccentric contractions 48 h after exercise. Mean [PGE2] in the two exercise modes remained unchanged over time and were practically equal at each time point. On the basis of these findings, we conclude that the magnitude of polymorphonuclear (PMN) activation, muscle damage, and DOMS are greater after eccentric than after concentric muscle contractions. However, the hypothesized interplay between muscle damage, increased PGE2 production, DOMS sensations, and reduced isokinetic muscle performance was not substantiated by the present results.

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 E(2) (PGE(2)), 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( degrees )/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 PGE(2) 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 PGE(2) 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 PGE(2) production in eccentric exercise-induced muscle damage, DOMS, and reduced isokinetic performance is not substantiated by the present results.

[Electric activity of the rectus femoris in supramaximal running]. / Activité électrique du droit antérieur dans la course d'intensité supramaximale.

The electrical activity of the rectus femoris has been analysed in nine subjects during the course of a supramaximal run performed until exhaustion. The integrated electromyogram and the median frequency do not change significantly as a function of time.

[Relation between maximal oxygen consumption and the record time in the 1500-meter run. Analysis of Lloyd's model]. / Relation entre la consommation maximale d'oxygène et le temps-record dans la course de 1 500 mètres. Analyse du modèle de Lloyd.

Lloyd's equation (Lloyd, 1967 b) has been applied to the calculation of record time in the 1 500 meters foot race from VO2 max. Twenty-eight healthy male subjects participated in this investigation. Record times decrease with increasing VO2 max. The theoretical curve plotted from Lloyd's equation is consistent with this trend. Moreover, the relationship between calculated record times (TRc) and measured record times (TRm) is highly significant (TRc = 74.3 + 0.7 TRm; r = 0.883; P less than 0.001). These results validate Lloyd's equation and hypothesis.

[Changes in the global electromyogram during static exercise; effect of age]. / Modifications de l'électromyogramme global lors de l'exercice statique: effets de l'âge.

In normal man, the EMG changes in forearm muscles holding a tension of 30% maximal voluntary strength for 5 minutes are: (1) an increase of integrated EMG, (2) a slight decrease of the median frequency of the EMG power spectrum. These changes are largely reduced with age.

[Moving platform as a new mode of equilibration evaluation]. / Mise au point d'un nouveau procédé d'évaluation de l'équilibration sur plate-forme mobile.

A platform of a new type was designed. By that means, the equilibrium of one individual can be evaluated. The platform is coupled with two electronics circuits. The first one records the oscillations of the platform using an A/D converter. The second one allows the man on the platform to watch on a standard TV set the position of the platform. A white square moves according to the motion of the platform.