The absolute number of sports injuries in the Netherlands is estimated at 2,9 million/year; 40% of these injuries are medically treated and ankle injuries are front runner (23% of all sports injuries). Ankle injuries are most frequently observed in soccer and volleyball. Measures to prevent such injuries are ankle taping & bracing. Research suggests that balance board training to improve propriocepcis and strength of the ankle joint muscles is also effective. However, scientific evidence for the effect of this simple-to-apply preventive measure is not conclusive. Such effect can only be shown in large RCT (n=1500). The NeVoBo is willing to host & adopt such a trial with the following questions: What is the effect of a preventive proprioceptive & balance board training program on the risk to sustain acute (fresh and recurrent) lateral ankle injury in volleyball players of the 3rd national league? What is the cost-effectiveness of such a program? What factors determine compliance with the program as part of the regular training routine?