Abstract :
[en] Introduction
The muscle injury, and more especially the hamstring strain, account for a large proportion of explosive top athletes injuries [1-3]. The subsequent down-time period has some sports and financial negatives consequences for the athlete, his team and/or his club [4, 5]. Despite the rehabilitation before return to play and prevention program, hamstring reinjury rates are still high (26% of all injuries) [6] and it's commonly accepted that a second injury is more severe than a first episode [2]. A more functional test could help the clinician in the return to play process decision to reduce the muscle injuries hamstring relapse.
Purpose
The aim of our methodology is to analyze, after medical clearance to resume sports activities, for athletes who suffered from grade II/III hamstring muscle strain, the biomechanics of the lower limbs during an explosive jump task.
Method
After (7,3±0,7 weeks) a grade II or III hamstring muscle tear, eight men (25±5,9 years), without past lower limb major injury, performed:
- an isokinetic test (knee maximal flexion-extension in concentric at 60°.s-1 and 240°.s-1 and knee maximal flexion in eccentric at 30°.s-1);
- a tridimensional biomechanics analysis of (bipodal and unipodal) squat jump and counter movement jump with Codamotion® system and Kistler® multicomponent force plates.
Results
A muscular lateral strength imbalance (±10% with p-value < 0,02) has been identified on the hamstring in concentric and eccentric by means of isokinetic testing, with the healthy side stronger than the pathologic. The main statistical significant outcome in the biomechanics analysis is the lower knee angle (±12% with p-value < 0,02) at the low point before the concentric pushing phase of the unipodal CMJ for the healthy leg than to the other one whereas there's no difference between both legs in an equivalent healthy population.
Discussion & conclusion
The tridimensional analysis appears to be complementary, not redundant, with the isokinetic strength testing due to the different nature of their informations obtained. It could be integrated in the return to play process decision expected the potentially interesting information about the player's biomechanics that it provides.
References
1. Ekstrand, J., M. Hagglund, and M. Walden, Epidemiology of muscle injuries in professional football (soccer). Am J Sports Med, 2011. 39(6): p. 1226-32.
2. Ekstrand, J., M. Hagglund, and M. Walden, Injury incidence and injury patterns in professional football: the UEFA injury study. Br J Sports Med, 2011. 45(7): p. 553-8.
3. Lopez, V., Jr., et al., Profile of an American amateur rugby union sevens series. Am J Sports Med, 2012. 40(1): p. 179-84.
4. Price, R.J., et al., The Football Association medical research programme: an audit of injuries in academy youth football. Br J Sports Med, 2004. 38(4): p. 466-71.
5. Verrall, G.M., et al., Assessment of player performance following return to sport after hamstring muscle strain injury. J Sci Med Sport, 2006. 9(1-2): p. 87-90.
6. Brooks, J.H., et al., Incidence, risk, and prevention of hamstring muscle injuries in professional rugby union. Am J Sports Med, 2006. 34(8): p. 1297-306.
