An electromyographic investigation of 4 elastic-tubing closed kinetic chain exercises after anterior cruciate ligament reconstruction.
OBJECTIVE
To determine the electromyographic (EMG) activity of the vastus medialis oblique (VMO), vastus lateralis (VL), semitendinosus and semimembranosus (ST), and biceps femoris (BF) muscles during 4 elastic-tubing closed kinetic chain exercises in postoperative patients with anterior cruciate ligament (ACL)-reconstructed knees.


METHODS
A 4 x 4 repeated-measures analysis of variance design guided this study. Independent variables were type of exercise and muscle; the dependent variable was EMG activity.


METHODS
Fifteen patients, 5 to 24 weeks after ACL reconstruction.


METHODS
Subjects performed 4 exercises (front pull, back pull, crossover, reverse crossover) with elastic tubing attached to the foot of the uninjured leg. Time-and amplitude- normalized EMG activity was recorded from the VMO, VL, ST, and BF muscles of the injured leg. The hamstrings: quadriceps ratio was calculated.


RESULTS
The normalized VMO, VL, and BF EMG activity ranged from 25% to 50% of maximum voluntary isometric contraction for the 4 exercises. The ST ranged from 12% on the back pull to 58% on the front pull. The hamstrings: quadriceps ratios were 137% (front pull), 115% (crossover), 70% (back pull), and 60% (reverse crossover).


CONCLUSIONS
We suggest that clinicians use these exercises during early ACL rehabilitation since they incorporate early weightbearing with hamstring and quadriceps coactivation.
Schulthies
S S
SS
Brigham Young University, Provo, UT 84602.
Ricard
M D
MD
Alexander
K J
KJ
Myrer
J W
JW