The effect of chiropractic adjustive therapy on the contractile strength of the hamstring muscle group in professional soccer players

M.Tech.Purpose: In soccer the re-injury rate of Hamstring muscle strains is between 12 and 14 percent. A previous or recent Hamstring injury is the most recognised risk factor for future injury. On recurrence of the injury, it tends to be more severe and disabling than the initial injury. Given the high recurrence rates, Hamstring injuries provide a significant challenge to the treating clinician. Knowledge surrounding optimal treatment and preventative measures is therefore critical (Hoskins and Pollard 2005). The aim of this study is to assess the effectiveness of lower lumbar spine segment adjustment, namely the L4/5 spinal level, in the contractile strength of the Hamstring muscle group in professional soccer players that have a history of a Hamstring strain. Design: Forty professional soccer players between the ages of 15 and 34 years with a history of a grade one or grade two Hamstring strain were considered for this study. Participants in this research were obtained from the University of Johannesburg inter-residence players and from the University of Johannesburg first soccer team. Two groups of twenty players were randomly assigned to one of two groups. Group A received spinal adjustive therapy (SAT) to the L4/5 spinal segment with an ultrasound treatment to their Hamstring muscle group and Group B will receive only the ultrasound treatment to the hamstring muscle group. Each participant was treated five times over a period of three weeks. Measurements: Before any intervention was given to either of the groups, Hamstring muscle contractile strength was first recorded using a Cybex system 2000. Hamstring contractile muscle strength measurements were taken again after the fifth treatment for both groups and compared to ascertain if there had been any change in the contractile strength of the Hamstring muscles. Results and Conclusion: Even though the two groups did not start at the same contractile strength for the Hamstring muscle in knee flexion, as measured a CCybex system 2000 possibly due to the selection criteria used in the study in terms of age and body weight of the participants, results showed that spinal adjustive therapy was more effective in improving the muscle contractile strength of the Hamstring muscle in knee flexion since there was a favourable difference in both Group A and Group B following intervention, but more so in Group A (in the once injured leg) which received spinal adjustive therapy due to a greater increase in the overall muscle contraction in the Hamstring muscle group. For the Chiropractic profession this opens huge potential with regards to the Chiropractic benefits and improving the functioning of professional soccer players