investigating the effects of blood flow restriction exercises on strength and cross section area of hamstring muscles and tendons: a case report

Introduction: hamstring injuries are one of the most common tendon injuries, especially in sports that require running and jumping. a comprehensive training program can help athletes to prevent this injury. among suggested exercises, the nordic eccentric training can reduce the injury rate by up to 50%; however, it is a high-load exercise that cannot be prescribed in the first stages of rehabilitation. here, we describe a football player who used low-load resistance exercise with blood flow restriction as an alternative method to strengthen their hamstring after nine months of anterior cruciate ligament reconstruction surgery. case description: a 19-year-old non-professional footballer with a body mass index of 22.18 kg/cm2 was invited to participate in this study. the variables examined included strength and cross-sectional area of the hamstring muscles (mean and maximum strength) and the cross-sectional area of the hamstring tendons at their origin. the treatment program included a seated hamstring curl with a load of 30% 1 rm with blood flow restriction for four weeks (thrice a week). results: the hamstring muscle strength improved by 6.54%, and the cross-sectional area of the muscles and tendons changed as follows: semimembranosus (tendon=0.07%, muscle=2.57%), semitendinosus (tendon=0.00%, muscle=-4.04%), and biceps-femoris (tendon=5.5%, muscle=4.34%). conclusion: low load resistance training with blood flow restriction in this athlete improved the strength and cross-sectional area of the hamstring muscles as well as the cross-sectional area of the tendons. the changes observed in tendon, and muscle cross-sectional areas were more prominent for biceps-femoris. this case showed that a training program with blood flow restriction may be a good alternative for people who cannot tolerate high-load exercises in the early stages of their rehabilitation. doing more extensive studies with more cases and a control group in the future can help our knowledge in giving the best exercise prescription to our patients.