Changes in muscle thickness after a hamstring muscle strain injury
Muscle strain, mainly hamstring muscle strain is one of the most common injuries associated with participation in intense sports and has a re-injury rate with reported values ranging from 12% to 35%. This high rate of hamstring muscle strain recurrence suggests that after injury, the muscle undergoes changes that could be risk factors for future injury.
A study was conducted to measure the change in hamstring muscle thickness between contracting and relaxing conditions following a return to sports after hamstring muscle thickness between contracting and relaxing conditions following a return to sports after a hamstring muscle strain and to evaluate the muscle function.
In the randomized trial, six male track and field sprinters participated in the study. All had an experience prior to hamster strain injury that required a minimum of 2 weeks away from sport participation. Transverse plane scans were also performed on the affected and unaffected sides under contracting and relaxing conditions i.e. proximal biceps femoris long head, proximal semi-tendinosus, middle biceps femoris long head and middle semi-tendinosus.
On the completion of study, results demonstrated an increase in the thickness of the middle biceps femoris long head and middle semi-tendinosus regions on the unaffected side with contraction. Whereas, the affected side did not show a significant increase. The proximal semi-tendinosus muscle thickness was increased with contraction on both the unaffected and the affected sides. The proximal biceps femoris muscle thickness did not show a significant increase on both sides. At the end, results of the study shows that evaluation of muscle thickness during contraction may be useful for assessing the change in muscle function after a hamstring muscle strain injury.