The muscle proteins in plasma increase after exertion (Clarckson, 1986 - Mair, 1992). Skeletal muscle damage may occur when the muscle are exposed to unaccustomed or eccentric loads, celullar muscle damage result in loss of muscle strenght and delayed onset muscle soreness (DOMS) (Sorichter, 2001). Increased concentrations of muscle proteins after unaccustomated exercise are accepted as markers of skeletal muscle damage (Mair, 1992) measurement of CK is the common method to determine muscle damage but without fiber type specificity (Sorichter, 2001). Serum troponin I isoform have proven to be a potent markers of striated muscle injury, elevated plasma levels indicates derangement of the myofibrillar apparatus (Rama, 1996). Troponin I as a constituant part of the muscular troponin-tropomyosin complex, inhibits at rest the interaction between F-actin and myosin and is bind to the two other troponin subunits.The aim of our study was to determinate muscle markers creatine kinase (CK) and skeletal troponin I (sTnI) in a group of young athletes suffering of delayed onset muscle soreness three days after an intensive training week. Methods Three rest days after an unusual intensive training week, we submitted a young athletes national level group (n=15) to muscle damage clinical and biological evaluation. Population: 8 males (mean age: 18± 2 years, poids=73± 6.8 kg, height 178±6 cm), 7 females (mean age=20± 2 years, weight=56± 4 kg, height 165 ± 6 cm). Analytical methods: Blood samples were collected for CK (kit Diagnostic Roche) and troponin I (sTnI) assays, sTnI (by lymphocyte hybridation, high affinity monoclonal antibodies (Mabs) were obtained and directed against the non-cardiac specific part of TnI and other high affinity Mabs directed against specific part of TnI. Two optimal pairs of Mabs were used for independant immunoenzymometric assays (IEMA). One assay measured total troponin I concentrations in blood, the other is highly specific for cardiac troponin I and shows no cross reactivity with skeletal troponin I. Results After three days resting recovery period all subjets present DOMS with a variability of intensity according to the athletes, we found high level CK for 9 subjects (male, female), 3 subjects (2 males, 1 female) are above normal range of sTnI (0.05 to 2.2ìg/l). The most important value of sTnI was found in the athlete presenting macroscopic recidivant muscle damage. We observed persistent elevation of CK, but this common muscle marker has a limited muscle fiber type specificity.sTnI is a protein unique to skeletal muscle and elevated plasma level indicates derangement of the myofibrillar apparatus. Rama (1996) observed the same high value after triathlon race normalised within 48 hours Sorichter (2001) evoked this muscle-type specific marker used in late diagnosis in the case of more extensive damage. In our study the higher sTnI values were found in athletes suffering of recidivant muscle symptoms and it will be interesting to improve the monitoring of muscle response in case of late muscle soreness or delayed severe muscle symtoms after specific training cessions and proposed an adapted training cession limiting the risks of secondary severe macroscopic muscle damage.
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