Andy has completed a rehabilitation program following a grade II hamstring strain. He returned to tennis but reinjured the hamstring after only 3 weeks. He had no complaints of pain with jogging,...

Andy has completed a rehabilitation program following a grade II hamstring strain. He returned to tennis but reinjured the hamstring after only 3 weeks. He had no complaints of pain with jogging, cutting, or jumping. He demonstrated 5/5 strength with manual muscle testing. What factors could have lead to his reinjury?