Article

Although closed (CKCE) and open (OKCE) kinetic chain exercises are used
in athletic training and clinical environments, few studies have compared knee
joint biomechanics while these exercises are performed dynamically. The purpose
of this study was to quantify knee forces and muscle activity in CKCE (squat and
leg press) and OKCE (knee extension). METHODS: Ten male subjects performed three
repetitions of each exercise at their 12-repetition maximum. Kinematic, kinetic,
and electromyographic data were calculated using video cameras (60 Hz), force
transducers (960 Hz), and EMG (960 Hz). Mathematical muscle modeling and
optimization techniques were employed to estimate internal muscle forces.
RESULTS: Overall, the squat generated approximately twice as much hamstring
activity as the leg press and knee extensions. Quadriceps muscle activity was
greatest in CKCE when the knee was near full flexion and in OKCE when the knee
was near full extension. OKCE produced more rectus femoris activity while CKCE
produced more vasti muscle activity. Tibiofemoral compressive force was greatest
in CKCE near full flexion and in OKCE near full extension. Peak tension in the
posterior cruciate ligament was approximately twice as great in CKCE, and
increased with knee flexion. Tension in the anterior cruciate ligament was
present only in OKCE, and occurred near full extension. Patellofemoral
compressive force was greatest in CKCE near full flexion and in the mid-range of
the knee extending phase in OKCE. CONCLUSION: An understanding of these results
can help in choosing appropriate exercises for rehabilitation and training.

Langue : ANGLAIS

Tiré à part : OUI