Objectives: 

Several models exist for inducing muscle damage in rats but rarely with a specific focus on trained subjects. Our aim was to design an eccentric-exercise induced injury in well trained, young rats, on a treadmill, which could simulate the situation of young trained athletes that suffer muscle injuries during competitive events.

Materials: 

60 Sprague-Dawley male rats with the initial weight of 0.180 (±0.030) kg upon starting the programme, and 0.390 (±0.020) kg on the day of downhill exercise. All the rats went through 10 days of preconditioning sessions followed by 10 days of training sessions before performing the downhill exercise sessions. The preconditioning sessions had the goal of acclimatising the rats to the function of the treadmill and to teach them to run continuously. The goal of the training period was solely to train the rats to be competent, fit runners and consisted of two training sessions per day. After 3 day rest, the downhill exercise session was performed twice on the same day. As an indicator of muscle damage, the plasma concentration of myglobin, creatine kinase and troponin-I, were measured at several time points, starting 1 d after the downhill exercise, and were compared with plasma levels measured the day before the downhill exercise sessions.

Results: 

The rats that went through the downhill exercise sessions all showed increased plasma levels of myoglobin, creatine kinase, and troponin-I, indicating muscle damage, compared with rats that did not undergo that particular session, indicating muscle damage.

Conclusions: 

The two sessions of downhill exercise were efficient in inducing muscle damage in the rats. Although the preparation period is relatively long compared to other existing methods we believe this simulation is rather more relevant to athletes than the other methods because the injury was associated with a natural locomotion on well developed muscles. From this point on, the application of rehabilitation should also reflect more a realistic outcome with a physiological point of view.