The Effect of Various Strength Training Protocols in ACL Reconstructed Participants

The purpose of the study is to determine how two different blood flow restriction training programs used in conjunction with standard rehabilitation affect leg strength. By doing this study, the investigator hopes to learn if one program improves strength and function more than the other. The investigator also hope to learn how the training affects the properties of muscle in participants who will or have had anterior cruciate ligament (ACL) reconstruction. These results will help define how the training programs are working. There will be no charge to the participant for their physical therapy visits as long as they are part of the study The initial visit and follow up assessment at the end of the training will each take up to 6 hours (2 hours for MRI, 2 muscle biopsy, 2 for muscle strength, movement mechanics and questionaires). The physical therapy visits will range from 60-120 minutes depending on the participant's stage of recovery and the activities to engage in. Training sessions will be held 3 days a week for approximately 4 weeks before surgery and up to 24 weeks after surgery. There will be a total of 4 additional study visits over a 7 month period. The first visit will be used to capture baseline conditions of their knee and thigh muscles (muscle biopsy, MRI, strength). The second visit will occur right before surgery to assess changes during prehabilitation (strength and walking mechanics). The third visit will occur 4-5 months after surgery and will be a complete reevaluation of their thigh muscle and knee function (muscle biopsy, MRI, strength, gait). The last visit will occur 6-7 months after surgery and will involve an assessment of their thigh muscle strength, walking, and jumping form. The muscle biopsy and magnetic resonance imaging portion of the study will occur in the outpatient unit of the Center for Clinical and Translational Science at the UK Medical Center and the MRI center located on the medical center campus. The muscle biopsy will take an additional 15 minutes and the MRI up to two hours (1 hour per leg). It can take up to 4 hours total to complete both procedures. The investigator will accommodate participant preference for scheduling.