The Impact of Hip Abduction Elastic-Resisted Neuromuscular Feedback on Frontal Plane Knee Kinematics in Female Volleyball Athletes

Abstract

Background: In female athletes, the knee is one of the most commonly injured areas of the body. Uncontrolled frontal plane knee motion or "valgus collapse" has been identified as a risk factor for knee injury. This movement pattern has been observed in cases of anterior cruciate ligament (ACL) tears in athletes and it has also been linked to the development of patellofemoral pain syndrome. While often seen during a body-weight squatting maneuver, the valgus collapse is magnified when the athlete either lands from a jump or attempts to accelerate into a jump. Knee injury prevention programs that emphasize knee separation have shown the ability to reduce the effect of the loss of valgus control and are associated with a decrease in knee injury risk. Purpose: The purpose of this study is to examine the impact of hip elastic-resisted neuromuscular feedback on frontal plane knee abduction during a counter jump maneuver. Design: Randomized, controlled repeated measure. Methods: In total, 20 female volleyball athletes (mean age, 16.4 6 1.6 years; age range, 15-18 years) were included in this study under the following condition: athletes should have had a pain-free dysfunctional squatting pattern with no signs of structural dysfunction. During a drop-jump test, the distance between the hips, knees, and ankles was measured via video analysis software. The separation distance between the knees (mid-patella width) and ankles (lateral malleolus width) was normalized by the hip separation (greater trochanter width) distance and measured at pre-landing, landing, and takeoff. Athletes were randomized into either a control group or a neuromuscular intervention group; a SquatGuide was used and variable resistance was manually applied to the distal femur to resist hip abduction by means of an elastic band. Before a volleyball practice session, the athletes in the neuromuscular intervention group performed 30 repetitions of a deep squat with variable resistance manually applied around the distal thighs; the SquatGuide was used to provide feedback on proper lower-quarter positioning. During this period, the control group did not participate in any activity. The jump landing characteristics of both groups were immediately re-examined before practice and again at 60 min at the conclusion of practice. Results: The means and standard deviations for the absolute distances (measures in centimeters) of knee and ankle separation and for the normalized knee and ankle separation were calculated. There was no correlation between the distance in the knee and ankle separation for each of the jump-land sequences. After squat training, statistically significant increases were found in the absolute distance (P < .001) and the normalized knee and ankle separation distance (P < .001) for all phases of the jump-land sequence, both immediately following the training and at 60 min after training.

The Association Between Temperament and Characteristics, Smartphone App Use Patterns and Academic Performance of University Students

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The Effect of Smartphone App-Use Patterns on the Performance of Professional Golfers

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