Evidence-based testing of the hamstring muscles using wireless surface emg

Background The re-injury rate of the hamstring muscle group is reported as high as 12%. This emphasises the need for better testing procedures when considering increasing the workload or allowing a player to return to sport. Objective To test the between-days reliability of functional exercises of the hamstring muscles using wireless surface Electromyography (sEMG; Kine ehf). Design The study was a test-retest design and sEMG was recorded on the hamstring muscles bilaterally. The exercises are: Nordic Hamstring Lower (HL), One leg horizontal hop (HH), 30 m sprint (S). A normalisation procedure preceded the testing, using maximum voluntary contraction of the hamstring muscles as reference measurement. Participants and setting The physiotherapist/principal investigator and three physiotherapist students participated as testers. Male players from two local soccer teams and the sports college were invited to participate. Of 48 players that were invited, 22 accepted and 16 completed the testing. Only players with no physical ailments were allowed to participate. The testing took place at an indoor soccer facility. Methods For HL, maximum power output quantified as MaxRMS and the percentage of the drop in median frequency (MF) through repetitions was calculated. For HH, MaxRMS was calculated. For S, total power output and MF was calculated. Data was analyzed for each exercise using paired t-test. Typical error (TE) was calculated for test/retest. Results No systematic error was detected. HL (MaxRMS): TE ranging from 21% to 44%. HL (MF): TE ranging from 107% to 170%. More results are pending. Conclusion TE is ranging at an unacceptable high level for HL. MaxRMS shows a lower TE value for all muscles compared to MF, indicating that a true change in the muscles activity will be easier detected with MaxRMS. Future studies need to be done to determine the cause(s) for this lack of reliability and possible techniques that can improve it.