KNEE BIOMECHANICS AND PHYSICAL PERFORMANCE;

AN ACL-RECONSTRUCTED ATHLETE BEFORE AND AFTER ISOKINETIC STRENGTH TRAINING.

Abstract

Introduction: A 29-year old male athlete (body mass: 64 kg; height: 172 cm)
sustained complete ACL rupture of the right knee. He was a martial-arts player and the injury
was repetitive, overuse in nature due to cyclic unilateral loading and unloading of the right
knee during training sessions. Rupture was diagnosed through detailed patient history, clinical
physical examination and was confirmed through magnetic resonance imaging (MRI) of the
right knee. Surgical reconstruction of the ACL was planned and a patellar tendon graft was
used. His baseline isokinetic data was recorded 4 months after the surgery. Objective: This
case study describes the effects of isokinetic strength training on knee biomechanics and
physical function of an ACL-reconstructed martial-arts athlete. Setting: Pakistan Sports Board
Islamabad. Study period: 40 days. Materials and Methods: Biodex System 3 Pro was used to
train the athlete for 15 sessions on alternate day basis. Average peak torque, average power,
total work and peak torque to body weight ratio were recorded for hamstring and quadriceps
before and after isokinetic rehabilitation. The athlete was positioned in the dynamometer with
upright back while hip and knee were flexed to 90 degrees. Unilateral isokinetic contractions
were performed according to a premeditated exercise protocol. Both hamstring and quadriceps
were tested isokinetically at five different movement speeds (30deg/sec, 90deg/sec, 150deg/
sec, 210deg/sec, and 270deg/sec). Five contractions were performed at each speed during
both knee flexion and extension. At baseline, average peak torque was higher at lower speeds
for both hamstring and quadriceps. Results: As a result of rehabilitation, average peak torque
for hamstring and quadriceps significantly improved at speeds of 150deg/sec and 90deg/sec
respectively. Average power, peak torque to body weight ratio, total work was also improved for
both hamstring and quadriceps. Two physical performance tests - agility run test and vertical
jump test - were used to assess the effects of training and both performance tests improved 51%
and 100% respectively. Conclusion: Isokinetic training improved the strength of quadriceps
and hamstring after ACL reconstruction. Hamstring muscle demonstrated greater traininginduced
increments in torque production compared to quadriceps at all contraction velocities.