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Single leg squat (SLS) is an important motion commonly observed in sports. Excessive dynamic knee valgus (DKV) during SLS may increase non-contact knee injury risks particularly in physically active females. As muscular strength plays crucial role in controlling DKV, the present study aims to evaluate the correlation between hip strength and knee frontal plane angle during SLS among females with and without excessive DKV. Thirty-four volunteers were allocated to the valgus (n = 17) and non-valgus (n = 17) groups. Their motions during SLS at 45° and 60° knee flexion were captured and analyzed using three-dimensional motion analysis system. Isokinetic hip strength was examined at 180°/s in flexion, extension, abduction, and adduction for both legs. Pearson's correlation test was computed to evaluate the relationship between hip strength and knee angle during SLS. Non-dominant hip extensor strength (r = −0.56, p = 0.02) and dominant hip adductor strength (r = −0.51, p = 0.04) were significantly related to the knee frontal plane angle during 45° SLS among those without DKV. Meanwhile, those with DKV showed a significant relationship between the knee frontal plane angle for both legs and non-dominant hip abductor strength during 60° SLS. Both groups demonstrated the relationship of hip strength on knee frontal plane angle during SLS, whereby increased hip strength may minimize excessive DKV. Those with excessive DKV should train to strengthen their hip abductor to reduce knee valgus particularly during deep squats. • Both women with and without DKV demonstrated the influence of hip strength on knee angle during SLS. • Women with and without DKV emphasize on different muscle groups at different squat depths. • In deep squats, training should focus on increasing the hip abductors strength. [ABSTRACT FROM AUTHOR]

Background The single leg squat (SLS) motion imitates various maneuvers in sports. It is commonly used as a functional test for the lower limb. SLS with two-dimensional (2-D) video analysis is regularly performed in the clinical setting to assess dynamic knee valgus (DKV). However, 2-D video analysis may not be able to demonstrate the same level of accuracy as three-dimensional (3-D) motion analysis. Purpose This study aimed to determine the within- and between-day reliability as well as the concurrent validity of 2-D and 3-D motion analysis of lower limb kinematics during 45° and 60° SLS among physically active females with and without DKV. Study Design Cross-sectional study Methods A total of 34 physically active females (17 individuals with excessive DKV and 17 without DKV) participated in the study. Their DKV was determined based on the cut-off values of knee frontal plane projection angle during drop landing. Their lower limb kinematics during SLS at 45° and 60° knee flexion were captured simultaneously by digital cameras (2-D motion capture) and infrared cameras (3-D motion capture). Intraclass Correlation Coefficient (ICC) was used as an indicator for within- and between-day reliability tests of both groups. Bland-Altman Plot and Pearson correlation were used to examine the validity of 2-D and 3-D motion capture methods in evaluating knee valgus angle. Results Two-dimensional knee FPPA and 3-D knee angle measured during 45° and 60° SLS in normal and excessive DKV groups showed moderate to excellent within-day and between-day reliability (ICC≥ 0.50). The current study showed that the 2-D knee frontal plane projection angle (FPPA) during 45° SLS were valid for the non-dominant leg in both groups. Additionally, the 2-D knee FPPA during 60° SLS were valid for non-dominant leg in excessive DKV group and dominant leg in normal group. Conclusion Two-dimensional knee FPPA during 45° and 60° SLS also showed high within- and between-day reliability for both groups. The validity of 2-D knee FPPA during SLS depends on the squat depth, stance leg, and presence of DKV. Level of Evidence 2B [ABSTRACT FROM AUTHOR]

Background. A range of non-contact injuries such as anterior cruciate ligament tear, and patellofemoral pain syndrome are caused by disordered knee joint loading from excessive dynamic knee valgus (DKV). Previous systematic reviews showed that DKV could be modified through the influence of hip strength and ankle range of motion. Therefore, the purpose of this systematic review was to examine the effects of exercise intervention which involved either top-down or bottom-up kinetic chains on minimizing DKV in male and female adults and adolescents, with and without existing knee pain. Methodology. Electronic searches were conducted in SAGE, Science Direct, SCOPUS, and Pubmed. The search strategy consisted of medical subject headings and free-text search keywords, synonyms and variations of ‘exercise intervention,’ ‘knee alignment,’ ‘dynamic knee valgus’, ‘knee abduction’ that were merged via the Boolean operator ‘AND’ and ‘OR’. The search was conducted on full-text journals that documented the impact of the exercise intervention program involving either the bottom-up or top- down DKV mechanism on the knee kinematics. Furthermore, exercise intervention in this review should last at least one week which included two or three sessions per week. This review also considered both men and women of all ages with a healthy or symptomatic knee problem. The risk of bias of the included studies was assessed by Cochrane risk assessment tool. The protocol of this review was registered at PROSPERO (registration number: CRD42021219121). Results. Ten studies with a total of 423 participants (male =22.7%, female =77.3%; adults =249, adolescents =123; pre-adolescent =51) met the inclusion criteria of this review. Seven studies showed the significant effects of the exercise intervention program (range from two weeks to ten weeks) on reducing DKV. The exercise training in these seven studies focused on muscle groups directly attached to the knee joint such as hamstrings and gastrocnemius. The remaining three studies did not show significant improvement in DKV after the exercise intervention (range between eight weeks to twelve weeks) probably because they focused on trunk and back muscles instead of muscles crossing the knee joint. Conclusion. Exercises targeting specific knee-joint muscles, either from top-down or bottom-up kinetic chain, are likely to reduce DKV formation. These results may assist athletes and coaches to develop effective exercise program that could minimize DKV and ultimately prevent lower limb injuries. [ABSTRACT FROM AUTHOR]

Introduction: Introduction: Knee valgus which also known as dynamic knee valgus (DKV), is frequently linked to non-contact lower-limb injuries, especially in females. This retrospective study aims to compare the kinematic variables of lower limb joints in physically active females with normal versus excessive DKV during single leg squat (SLS) at 45° and 60° knee flexion. Methods: Based on the outcomes of drop vertical jump screening test, 34 females were recruited and divided into two groups (i.e., normal and excessive DKV). Participants performed SLS at 45° and 60° knee flexion with three-dimensional motion capture and analysis. The kinematic variables of lower limb joints at both knee flexion of SLS were compared across groups using independent T-test. Results: During 45° SLS with the dominant limb, the normal DKV group performed significantly greater hip adduction angle (4.49±3.25°, t(32) = 2.371, p= 0.024) than the excessive DKV group (1.426±4.23°). During 60° SLS with the dominant limb, the normal DKV group showed knee adduction (0.223±0.07°, t(16.048) = 10.707, p=0.001) while the excessive DKV group showed knee abduction (-4.478±1.81°). Conclusion: Females with excessive DKV showed significantly different lower limb kinematics and motion control strategy compared to females with normal range of DKV. The findings highlighted the importance of DKV screening among physically active females, and the rationale for prescribing individualized exercise intervention to prevent lower limb non-contact injuries. [ABSTRACT FROM AUTHOR]