RELATIONSHIP BETWEEN ISOKINETIC LEG STRENGTH AND KNEE FRONTAL PLANE PROJECTION ANGLE DURING SINGLE LEG SQUAT AMONG MALE JUNIOR ATHLETES

@#Background: Those with increased dynamic knee valgus are vulnerable to increased risk of non-contact knee injuries. However, studies on the top down kinetic chain of lower limb mechanics during dynamic motions such as single leg squat (SLS) among trained males were scarce. Objective: The objective of the study was to evaluate the relationship between isokinetic hip and knee strength and frontal plane projection angle (FPPA) of the knee joint during SLS. Methods: Thirty-two male junior athletes (twelve cyclists, ten runners and ten squash players) were screened for excessive dynamic knee valgus (DKV) prior to participation. Only those within the normal value of DKV were included. Their hip and knee isokinetic strength in sagittal plane were evaluated at 60º/s of angular velocity for both legs using dynamometer. Two dimensional knee FPPA was evaluated during SLS at 60º of knee flexion. Pearson correlation was evaluated between knee FPPA during SLS and isokinetic leg strength. Results: Correlations between knee FPPA and hip and knee isokinetic strength were not statistically significant except between knee flexion peak torque/body weight (r = -0.35, p = 0.05) and hamstring to quadriceps ratio (r = -0.39, p = 0.03) of non-dominant leg. Conclusions:Isokinetic hip and knee strength and knee FPPA during SLS was correlated only for non-dominant leg during SLS among male junior athletes. DKV during SLS may be reduced through strengthening the muscles around hip and knee joints.

Differences in dynamic alignment and flexibility between junior high-school and high-school female basketball players / 体力科学

To identify athletes at a higher risk of anterior cruciate ligament (ACL) injury, we developed a video-based screening test focused on hip abductor and rearfoot function. However, age differences in hip or reafoot motion as a contributor to dynamic knee valgus remains unclear. The purpose of this study was to determine how age differences contribute to hip or reafoot motions. Eighty-three female basketball players (41 junior high-school and 42 high-school students) agreed to participate in this study. Participants were measured for hip rotation angle, tibial rotation angle, ankle dorsi-flexion angle, navicular drop and general joint laxity. Subjects also performed single-legged squatting and drop landing from a 30 cm box. Knee-in distance (KID) and Hip-out distance (HOD) were measured using 2-dimensional video images filmed at 30 Hz. Additionally, Dynamic Trendelenburg Test (DTT) and Heel-Floor Test (HFT) were performed. The prevalence of HFT-positive in junior high-school and high-school athletes were not statistically different. DTT-positive during landing was more prevalent in junior high-school athletes than in high-school athletes (P<0.05). Junior high-school athletes demonstrated greater HOD values in squatting than high-school athletes (P<0.05). The range of motion in high-school athletes was significantly greater than in junior high-school athletes in tibial external rotation, hip internal and external rotation (p<0.01). The navicular drop in junior high-school athletes was significantly greater than in high-school athletes (p<0.01), however the navicular height was greater in high-school athletes (p<0.01). Player's age is an important consideration in ACL injury preventative conditioning.