Effects of four different relative loads on knee joint kinetics during the barbell back squat.

The barbell squat is fundamental in strength and conditioning. Unfortunately, the propensity for injury is high particularly at the knee. The aim of the current investigation was to examine the influence four different relative squat loads (40, 50, 60 and 70 % 1 repetition maximum) on the forces experienced by the patellofemoral joint and patellar tendon. Patellofemoral and patellar tendon loads were obtained from twenty five experienced male participants. Differences between squat conditions were examined using repeated measures ANOVA (p<0.0125). Significant increases (p<0.0125) in patellofemoral and patellar tendon forces were identified in the 60 and 70 % 1 repetition maximum conditions. It may be prudent therefore for lifters who are predisposed to patellofemoral and patellar tendon injuries to utilize lower relative squat loads to reduce their risk from knee pathology.