The effect of a neck strengthening exercise program on concussion in high school aged athletes.

The intervention arm will consist of a 6-week intensive neck strengthening exercise program to be completed 3 times per week. After 6-weeks, a maintenance exercise program will be implemented once per week for 4-months. It will also include completion of a concussion education session. The control arm will consist of usual training and the same concussion education. The intervention exercises will be supervised by an experienced physiotherapist and will be delivered in groups of 10-12 athletes. Exercise effort/load will be determined using a percentage of 1 repetition maximum (1RM) which will be assessed at baseline and 6 weeks using a hand held dynamometer. The intervention exercise program will be divided into 3 phases: 1. Familiarisation and technique acquisition 2. Dynamic strengthening 3. Maintenance Phase 1 Familiarisation and technique acquisition All exercises will be isometric with load and sets/repetitions individually prescribed for each athlete based on their 1RM from baseline testing. Athletes will progress from phase 1 to phase 2 once they can complete 3 sets of 8 repetitions at 60% of 1RM for each direction of neck movement; flexion, extension, left lateral flexion and right lateral flexion whilst maintaining good exercise technique. Phase 1 is expected to last approximately 2 weeks. All of the exercise programs will be accompanied by written instructions on how to complete each exercise. Phase 2 Dynamic strengthening Athletes in phase 2 will progress onto more dynamic exercises to include isotonic movements for rotation, as well as coupling isometric neck exercises with isotonic movement of the upper and lower limbs. Load and sets/repetitions will be individually prescribed for each athlete by the supervising physiotherapist based on their 1RM from baseline testing. All of the exercises will be accompanied by written instructions on how to complete each exercise. Phase 2 is expected to last 2-4 weeks. Load for the neck will remain at 60% 1RM but the complexity of the exercise will increase. Athletes are also aiming to complete 3 sets of 8 repetitions whilst maintaining good technique. All athletes will progress onto phase 3 maintenance after the 6-week re-assessment of outcome measures. Phase 1 and 2 exercises will be completed 3 times per week during the intensive 6-week period. Phase 3 maintenance exercises will be completed once per week during the 4-month maintenance period. Phase 3 Maintenance Maintenance will continue for all athletes from 6 weeks to the end of the study period (6-months). All exercise program’s will be individualised for each athlete. The exercises contained within the maintenance program will be a mixture of isometric and isotonic exercises. The exact combination will depend on the athlete’s progress during phase 1 and 2. This will be determined by the supervising physiotherapist. The duration of each exercise session will be approximately 5 minutes per athlete (exercises will be incorporated into their usual strength and conditioning routine and will be completed following completion of their usual upper limb exercises). Exercise adherence will be monitored using a paper-based exercise log book/ diary to be completed by each athlete following completion of the neck exercises. This will be transferred to an electronic spreadsheet by the researcher each week. One online concussion education session will be provided which will be approximately 1 hour in length, provided online by the research team (using voice over power point). Topics covered will include: what is concussion, signs and symptoms and management of concussion aimed at the level of adolescents and their parents. The concussion education will be completed by both arms before the intervention group commences the 6-week neck strengthening exercise intensive. All eligible contact sport athletes will complete measures for neck strength, demographic survey, anthropometric and concussion incidence. In addition, all eligible football (soccer) players will complete head acceleration measurements during purposeful heading drills.