Subjects were 234 adolescents (mean age: 16 years) who were categorised by gender, activity level and type of sport played. Subjects jumped from a box 0.3 metres high to land on a force plate. Results showed that there were no significant differences (p>0.05) across gender, activity levels, and type of sport played. Across all subjects, the mean peak vertical GRF was 4.5 bodyweights (SD: 1.7). In regard to gender, mean peak vertical GRFs were 4.6 (SD:1.7) and 4.2 (SD:1.4) for males and females respectively. The mean peak vertical GRF for subjects involved in recreational sport 1–3 times per week was 4.4 bodyweights (SD:1.7), while the mean for those playing competitive sport 4–7 times per week was 4.5 bodyweights (SD: 1.7). The mean peak vertical GRF for subjects participating in sports involving jumping and landing activities was 4.6 bodyweights (SD: 1.8) as compared to 4.4 bodyweights (SD: 1.5) for subjects in sports that did not involve jumping activities.