Knee flexor muscle fatigue during repeated Nordic hamstring exercise.

BACKGROUND: Nordic hamstring exercise is an effective method for preventing hamstring strain injury. In this study, we investigated the response of knee flexors regarding increased muscle force and fatigue when the Nordic hamstring exercise was performed repeatedly to further understand how it can prevent hamstring strain injury. METHODS: The Nordic hamstring exercise was performed 10 times by 53 athletes; knee flexor peak tensile force and the respective flexion angle were compared at different phases during this sequence: phase 1, 1st Nordic hamstring exercise force; phase 2, mean value during the 2-4th repetitions; phase 3, mean value during the 5-7th repetitions; and phase 4, mean value during the 8-10th repetitions. We also divided the knee flexor peak force into deep and slight flexion zones and evaluated changes during different phases. RESULTS: Knee flexor peak force was most significant in phase 2 and decreased during subsequent phases. The knee angle at which peak force was exerted was greatest in phase 1 and decreased thereafter. When we compared the knee flexor peak force in different flexion angle zones, increased muscle force in the slight flexion zone was greater than increased muscle force in the deep flexion zone in phases 2 and 3. CONCLUSIONS: Enhancement of the knee flexor force, especially in the slight flexion zone occurs after only a few repetitions of the Nordic hamstring exercise.

Development of a database for educating athletes in university sports.

[Purpose] The aim of this study was to investigate the development of a database and system for easily creating documents for educational guidance on a personal computer and to assess the efficacy of such a system. [Participants and Methods] Thirty-seven athletic trainers of students who belonged to an athletic department participated in the study. We used FileMaker Pro 17 Advanced for document creation, and data on independent exercises for athletic rehabilitation were used for database creation. The participants created educational documents for the athletic rehabilitation of ankle sprains using paper media and this system. We surveyed the following items and compared them between the groups: 1) time taken to create the documents, 2) difficulty of creating menus for educational coaching, and 3) the potential for ongoing provision of self-training menus. [Results] The preparation times for creating the rehabilitation menu were significantly lower using the database than using paper media. As a result of the questionnaire survey, we found that using the database was significantly better than using paper media in terms of ease of menu creation and the potential for ongoing provision of self-training menus. [Conclusion] Our results suggest that educational coaching for rehabilitation using a database would be valuable for student athletic trainers.