From the article:

Risky play is associated with greater resilience, self-confidence, problem-solving and social skills such as cooperation, negotiation and empathy, according to studies by Sandseter and others. When a study in Leuven, Belgium, gave four- and six-year-olds just two hours a week of opportunities for risky play over the course of three months, their risk-assessment skills improved compared with those of children in a control group2. In this study, the risky play took place at school, in a gym class and in the classroom.