KANNUS, P. and M. JÄRVINEN. Prediction of torque acceleration energy and power of thigh muscles from peak torque.Med. Sci. Sports Exerc, Vol. 21, No. 3, pp. 304–307, 1989. The purpose of this study was to assess the relationship between the isometric and isokinetic peak torque (PT) (speed of movement 0, 60, and 180°·s-1) and the peak torque acceleration energy (PTAE) and average power (AP) of multiple contractions (180°·s-1) of the quadriceps and hamstrings in 38 patients having a chronic, complete anterior cruciate ligament (ACL) insufficiency in the knee. At every test speed the Pearson product moment (r) and the Spearman rank (rs) correlation coefficients between the PT and PTAE were highly significant for both muscle groups in the uninjured (r = 0.79–0.94, rs= 0.78–0.94) as well as in the ACL-insufficient (r = 0.87–0.95, rs= 0.83–0.94) knees. The results were the same between the PT and AP (uninjured: r = 0.70–0.90, rs= 0.68–0.90; ACL insufficient: r = 0.86–0.93, rs= 0.82–0.93). In both knees and in both muscle groups the correlation coefficients increased simultaneously with the speed of movement, obviously since the PTAE and AP were registered at the highest test speed (180°·s-1). In conclusion, concerning ACL-insufficient or uninjured knees, the PTAE or AP analysis may offer little additional information about thigh muscle function to that attained by more simple measurement, the PT analysis.