Why do volleyball, handball, and tennis players have such a high risk of shoulder injuries, and could this risk be reduced? Professor Bénédicte Forthomme of the University of Liege provides clear and innovative insight into these questions, which can create problems for high-level athletes.

The player suddenly pulls their arm back high above their shoulder, then quickly slams it down to send the ball flying through the air... Volleyball players know this cocking/hitting or throwing motion by heart. Their dominant shoulder does too. But this smashing motion is not without risk, and can cause a range of strain injuries. Over time, these strain injuries can lead to pain or more serious injury, sometimes forcing the player to sit out (at least) part of the season. Whether athletes play volleyball, handball, tennis, or any other sport in which the shoulder is used intensively, there is always a risk of overuse. However, players will no longer have to choose between love of the game and injury prevention, thanks to a study led by Bénédicte Forthomme, a Lecturer in the Department of Motricity at the University of Liege, and the head physiotherapist at the Liege University Hospital. 

"It turns out that 20% of volleyball (and handball) players suffer from shoulder injuries during their season. Their symptoms can force them to miss trainings and games for up to six weeks. Interestingly, the study showed that after an initial shoulder injury there is a 9-fold risk of suffering from another injury in the following season," explains the physiotherapist. Consequently, her objective is clear: improve the situation by protecting athletes' shoulders better through training and an injury prevention programme that is adapted to each player's risk factors.

Up to now, few scientific studies have attempted to identify the risk factors for shoulder injuries. "The shoulder is actually very complex. This fact, in addition to the difficulty engendered by a prospective approach, may explain why so few studies have been conducted," suggests Bénédicte Forthomme. Clearly, this complexity doesn't frighten her: since she obtained her degree in 1989, she has mainly been treating shoulders, and has complemented her clinical practice with research published in a variety of journals.

A problem all athletes face

"The shoulder is a joint complex with eloquent anatomical features: the shoulder complex is made up of five joints surrounded by 19 muscles. The physical structure of the joint surfaces provides the shoulder with the widest range of movement in the entire body,” she explains. This wonderful mobility allows for movements in three directions, but comes with a disadvantage: the main shoulder joint (which connects the humerus to the scapula) becomes unstable when the player's arm is cocked. The player's arm is in an extreme position, as it is pulled very far back in order to gather energy to strike the ball, and then must quickly decelerate. During this movement there is the risk that the humeral head will be pulled away from the glenoid cavity.

"By subjecting their shoulders to such a demanding movement, which puts a lot of strain on the joints, high-level athletes (and those who simply play regularly) increase their likelihood of injury," continues the scientist. This risk is even higher in asymmetrical sports that use a dominant arm. 

"In young volleyball players we can already see mechanical adaptations to the cocking/hitting movement," she states. And the higher the athlete's level, the greater the risk of injury. Indeed, repetition of the movement causes a number of specific muscle modifications that potentially increase the risk of injury. This is why a preventative strategy should be the main priority for sports in which there is intensive use of the upper limb."