Biomechanical analysis of groin related strength training exercises for injury prevention
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- Master theses 
Purpose: Groin injuries in soccer are a widespread problem in sports medicine. One certain strength exercise, the Copenhagen adductor exercise, has shown an injury-preventing effect. But there are still many groin injuries, and better preventive measures are needed. The aim of this study was to investigate the load on groin structures during the performance of the Copenhagen adductor and three other exercises designed with a hypothesis of having a greater load. All are one-foot dynamic plank exercises. The Copenhagen adductor exercise is conducted by hip adduction, while the others had hip adduction, hip flexion, and a combination of both to resemble a soccer pass. More specific, muscle activation of the adductor longus muscle and the rectus femoris muscle were examined as well as torque exerted on the hip joint. Methods: 18 footballers (10 men and 8 women) at varying playing levels in the Oslo region performed the four plank exercises, while electromyography activity, motion capture and forces were recorded. Muscle activations were found from the electromyography data and normalized to a player’s maximum activation for the given muscle. By motion capture, the position of hip joints and force direction were determined. Together with measured forces, this was used to calculate torque and further normalised to the player’s weight. Both average mean values and peak values were calculated and used for comparison by Results: With a p-value set to 0.05, all exercises with hip adduction achieved significantly higher muscular activation of adductor longus than the exercise without. Exercise including only flexion of the leg showed significantly higher activation of rectus femoris than exercises including only adduction and both adduction and flexion. The muscle activation seemed to be higher during concentric muscle work rather than eccentric muscle work. None significantly differences were found in torque between the exercises, but it showed that torque was greatest early in the concentric phase for all exercises. Conclusion: Four exercises were investigated, and trend was shown of greater total load on one exercise intending to resemble a soccer pass compared to the Copenhagen adductor exercise. It should be investigated further whether this more sport-specific exercise has greater preventive potential. To ensure high activation on both adductor longus and rectus femoris, one single exercise does not seem to be sufficient, a combination of several exercises should be performed.