The effect of core muscle fatigue on squat kinematics in female Athletes

Poster Presentation
Paper ID : 1840-12THCONG
Oral / Poster Presentation File: 1840.jpg 
1Assistant Professor, Sport Injuries, Sport Sciences Research Institute (SSRI)
2Student of Islamic Azad University of Karaj, Sport Injuries
3Assistant professor, Sport injuries, Sport Sciences Research Institute
Neuromuscular fatigue is the reduction of the maximum force produced by a group of muscles, which can change the kinematics of the lower limb by changing the pattern of muscles activation and the result is an increased risk of injury. The effect of fatigue on movement patterns in musculoskeletal screening tests, including squats, is an important first step in informing injury screening and guiding further future research on sport injury prevention.
According to G-Power software, and based on the results of Benjamin et al. (2015) and considering knee valgus data in healthy women before and after fatigue and assuming = 0.05α and 1-β = 0.95, The statistical sample of the study is 16 female athletes (18-25 years old) in Karaj. After observing the ethics in the research and reviewing the inclusion and exclusion criteria, the subjects entered the measurement process. Subjects performed squats twice before and immediately after the fatigue protocol. Kinematic information in frontal and sagittal planes while squatting was recorded using two digital video cameras with a recording speed of 50 Hz and a resolution of 21 megapixels. The resulting video images were analyzed for two-dimensional kinematics by Quinoa Motion Analysis Software.
Paired Sample T-Test was used to compare the results of kinematic variables before and after the fatigue protocol.
The results of this study showed that central body fatigue could be associated with decreased knee flexion and increased knee valgus during squat movement, but no difference was observed in hip flexion and ankle dorsiflexion before and after the fatigue protocol.
The increase in knee valgus may be due to the fact that fatigue of the core region has exhausted the muscles that control the pelvis at the frontal plane, ie the gluteus maximus and medius; these muscles are no longer able to properly maintain the position of femur and pelvis, causing inward rotation of femur and close to the midline of the body and rotate inward along its longitudinal axis, and knee valgus while squatting. The reduction in knee flexion during Squat can be thought of as a way to shorten movement due to fatigue.