The Effects of a New ACL-Injury Prevention Device on Knee Kinematics and Hamstring and Quadriceps Co-Contraction: A Pilot Study
Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
Background: The incidence of anterior cruciate ligament (ACL) –injury is 3-5 times greater in female athletes compared to male athletes. This may be partially attributed to lower levels of hamstring-quadriceps co-contraction in females with subsequent knee kinematics that increases risk of ACL-injury. Finding training methods that improves co-contraction and increases knee stability is important.
Objectives: To evaluate the effects of a new device on hamstring-quadriceps co-contraction and to investigate if training with the device can alter knee kinematics in female athletes.
Study design: Controlled experimental study design with repeated measures.
Method: Twenty soccer and floor ball athletes were measured with electromyography (EMG) for hamstring-quadriceps co-contraction while performing squats with and without the device. Thirteen athletes also underwent three-dimensional kinematic analyses, measuring knee abduction angles (at initial ground contact and peak angle) during a drop jump, before and after a six week intervention period with the device. Friedman’s test and Wilcoxon signed rank test was used to assess differences and effect sizes (ES) were calculated.
Results: Co-contraction was consistently larger on the device (medial side: p<0.001, ES=0.88; lateral side: p<0.001, ES=0.80) and the ratio of medial-to-lateral co-contraction increased (p=0.001, ES=0.79). In the kinematic analysis low adherence rates amongst our subjects meant that the effects of the device on kinematics could not be measured.
Conclusion: Performing squats with the new training device stimulates increased hamstring-quadriceps co-contraction and increases the ratio of medial-to-lateral co-contraction. The effects of the device on knee kinematics have yet to be determined.
Place, publisher, year, edition, pages
2013. , 25 p.
Hamstring-quadriceps co-contraction; dynamic valgus; knee abduction, anterior cruciate ligament (ACL) injury; injury prevention, gender differences
Sport and Fitness Sciences
IdentifiersURN: urn:nbn:se:hh:diva-20561OAI: oai:DiVA.org:hh-20561DiVA: diva2:585799
Subject / course
Biomedicine Targeting Physical Education
UppsokLife Earth Science
Bremander, Ann, PhDBrorsson, Sofia, PhD
Olsson, Charlotte, Associate Professor