Predictions of Total Work Based on Measures of Muscle Strength and Hop Performance in Individuals after ACL Reconstruction

A tear to the anterior cruciate ligament (ACL) is a devastating injury that commonly results in ACL reconstruction (ACLR) and can have detrimental effects on an individual’s activity level, extracurricular participation and future joint health. Muscle strength and hop performance are common clinical tools to evaluate readiness for return to sports participation, but limited information is known regarding how these measures relate to specific measures of athletic performance. The purpose of this study was to determine the association between measures of hop performance and muscle strength with total work during a single leg vertical jump task in young athletes after ACLR. Total work was used to quantify cumulative power during a single leg vertical jump. Fifty-one individuals (36 females, age 14-23) with unilateral ACLR, who were cleared by a physician to return to their sport following ACLR and rehabilitation, participated in the study. Participants performed a repeated single leg vertical jump for 10 seconds on a force plate, which measured power generation and absorption during each single-limb takeoff and landing. Total work (J) was calculated by summing the area under the positive and negative power curve. Clinical data gathered included performance on a 6-meter timed hop (seconds), single hop, triple hop and crossover hop for distance (cm). Quadriceps femoris and hamstring strength (Nm) were calculated with an isokinetic dynamometer using isokinetic (180°/s, 300°/s) and isometric testing. Through regression analysis, nearly all clinical measures significantly predicted variance in power output during the vertical jump task. Quadriceps femoris strength at 180°/s was the strongest predictor (highest R2 adjusted value) of total work for both the involved and uninvolved limb after accounting for height and weight. Future research is needed to understand the association between performance on the repeated vertical single leg jump test and sport performance after ACLR to better predict a successful return to sport.A three-year embargo was granted for this item.Academic Major: Exercise Science Educatio