The aim of this study is to investigate the effect a specific exercise program on the incidence of injuries in the lower extremity. 72 elite orienteerers, aged 18-40 years, are allocated to an intervention or control group. The intervention group performs four specific exercises, four times a week (10 minutes per session) in conjunction with normal training. Injury data are collected every second week using valid injury questionnaire distributed by text messages over 14 weeks. Primary outcome is number of substantial injuries in the lower extremity. Secondary outcomes are incidence of ankle sprains and the average substantial injury prevalence across the 10 weeks.

The high physical load associated with running through uneven terrain contributes to that orienteerers are exposed to high injury risk, where the majority of injuries located in the lower extremities. Specific training programmes have been effective at reducing injury risk in sports. Yet, not trial has been conducted in elite orienteering. The aim of this study is to investigate the effect a specific exercise program on the incidence of injuries in the lower extremity. 72 elite orienteerers, aged 18-40 years, are allocated to an intervention or control group. The intervention group performs four specific exercises, with three difficult levels intensified every second week over the first four weeks, targeting strength, flexibility and coordination of the lower extremity. The exercises are completed four times a week (10 minutes per session) in conjunction with normal training. Injury data are collected every second week using valid injury questionnaire distributed by text messages over 14 weeks. Primary outcome is number of substantial injuries in the lower extremity. Secondary outcomes are incidence of ankle sprains and the average substantial injury prevalence across the 10 weeks. Participants will be recruited in January-February 2018. The intervention starts in February 2018 and data collection will be completed in June 2018. Data analyses are expected to be completed in October-November 2018.

Due to high injury risk and lack of injury prevention trials in orienteering, a RCT investigating the effect of a specific exercise program on the incidence of injuries in the lower extremity, is warranted. The results of this trial will be beneficial to orienteerers, clubs, federations and increase our understanding on how lower extremity injuries can be prevented in a physically challenging sport.

Inclusion Criteria:

Adult elite orienteerers Aged 18-40 years Participating in the highest national orienteering league (Swedish League) Participant inclusion criteria - Age group: Adult Participant inclusion criteria - Gender: Both

Exclusion Criteria:

Injured adult elite orienteerers not able to perform baseline tests

Test assessors and data collectors will be blinded to treatment allocation. The randomized phase will be unblinded after 14 weeks of data collection and the long-term follow-up (4 months) will be conducted by test assessors blinded to treatment allocation.