EFFECTS OF PROLONGED L-CARNITINE ADMINISTRATION ON DELAYED MUSCLE PAIN AND CK RELEASE AFTER ECCENTRIC EFFORT

Eccentric muscle effort is known to induce delayed muscle soreness (DO MS) and muscle damage which are not responsive to medical treatment wi th the most common analgesic agents. The aim of the study was to inves tigate the effects of oral L-carnitine supplementation on pain (VAS sc ale), tenderness (pain thresholds) and CK release induced by a 20-min eccentric effort of the quadriceps muscle. A single-blind study was ca rried out on 6 untrained subjects (mean age: 26 +/- 3.8 yrs; mean heig ht: 173 +/- 4.6 cm: mean body weight, 68.3 +/- 4.5 kg) over 7 weeks du ring which each subject: a) was given 3 g/day of placebo for 3 weeks a nd, after a week's interval, 3 g/day of L-carnitine for 3 weeks; b) pe rformed 2 step tests on the first day of the 3rd and 7th week invertin g the order of the;exercising limb. In a separate set of experiments c arried out 8 months later, the possible effects of training on pain pa rameters and CK levels were also investigated in the same subjects who performed 2 step tests at a 4-weeks' interval, without medication. L- carnitine significantly reduced pain, tenderness and CK release after the effort with respect to placebo, In contrast, no significant differ ence was found in the parameters measured between the hive tests perfo rmed without medication. It is concluded that L-carnitine has a protec tive effect against-pain and damage from eccentric effort. This effect is mainly attributed to the vasodilation property of the compound,whi ch both improves energetic metabolism of the hypoxic/damaged muscle an d enhances wash-out of algogenic metabolites.