Side‐to‐side differences of lower extremities may influence the likelihood of injury. Moreover, adding the complexity of jump‐landing direction would help to explain lower extremity control during sport activities. The aim was to determine the effects of limb dominance and jump‐landing direction on lower extremity biomechanics. Nineteen female volleyball athletes participated. Both dominant limbs (DLs) and non‐dominant limbs (NLs) were examined in single‐leg jump‐landing tests in four directions, including forward (0°), diagonal (30° and 60°), and lateral (90°) directions. Kinematic marker trajectories and ground reaction forces were collected using a 10 camera Vicon system and an AMTI force plate. Repeated measures ANOVA (2 × 4, limb × direction) was used to analyse. The finding showed that, at peak vertical GRF, a significant interaction of limb dominance and direction effects was found in the hip flexion angle and lower extremity joint kinetics (p < .05). NLs and DLs exhibited significantly different strategies while landing in various directions. Significantly higher increase of ankle dorsiflexion angle was observed in lateral direction compared to other directions for both DLs and NLs (p < .05). Increasingly using ankle dorsiflexion was observed from the forward to the lateral direction for both DLs and NLs. However, NLs and DLs preferentially used different strategies of joint moment organization to respond to similar VGRFs in various directions. The response pattern of DLs might not be effective and may expose DLs to a higher injury risk, especially with regard to landing with awkward posture compared with NLs.

Knee joint coordination during jump landing in different directions is an important consideration for injury prevention. The aim of the current study was to investigate knee and hip kinematics on the non-dominant and dominant limbs during landing. A total of 19 female volleyball athletes performed single-leg jump-landing tests in four directions; forward (0°), diagonal (30° and 60°) and lateral (90°) directions. Kinematic and ground reaction force data were collected using a 10-camera Vicon system and an AMTI force plate. Knee and hip joint angles, and knee angular velocities were calculated using a lower extremity model in Visual3D. A two factor repeated measures ANOVA was performed to explore limb dominance and jump direction. Significant differences were seen between the jump directions for; angular velocity at initial contact (p < 0.001), angular velocity at peak vertical ground reaction force (p < 0.001), and knee flexion excursion (p = 0.016). Knee coordination was observed to be poorer in the early phase of velocity-angle plot during landing in lateral direction compared to forward and diagonal directions. The non-dominant limb seemed to have better coordination than the dominant limb during multi-direction jump landing. Therefore, dominant limbs appear to be at a higher injury risk than non-dominant limbs.

Background: Excessive knee valgus has been strongly suggested as a contributing key factor for anterior cruciate ligament (ACL) injuries. Three-dimensional (3D) motion analysis is considered the “gold standard” to assess joint kinematics, however, this is difficult for on-field assessments and for clinical setting. Purpose: To investigate the concurrent validity of 2D measurements of knee valgus angle during cutting in different directions and to explore intra-rater and inter-rater reliability of the 2D measurements. Study Design: Descriptive laboratory study Method: Seven recreational soccer players participated in this study. Participants performed three trials of cutting maneuvers in three different directions (30º, 60º, and 90º) with the dominant leg. Cutting maneuvers were recorded simultaneously with a video camera and a Vicon^TM motion capture system. Knee valgus angle from 2D and 3D measurements at initial contact and at peak vertical ground reaction force (vGRF) were extracted. The Pearson’s correlation was used to explore the relationship between the 2D and 3D measurements, and reliability of the 2D measurements were performed using intraclass correlation coefficients (ICC). Result: Significant correlations between 2D and 3D knee valgus measurements were noted for 60º (r = 0.45) and 90º (r = 0.77) cutting maneuvers at initial contact. At peak vGRF, significant correlations between 2D and 3D knee valgus measurements were noted for 30º, 60º, and 90º cutting maneuvers (r=0.45, r=0.74, r=0.78), respectively. Good-to-excellent intra-rater and inter-rater reliability of the 2D knee valgus measurements was observed during cutting in all directions (ICCs: 0.821-0.997). Conclusion: Moderate-to-strong correlation between 2D and 3D knee valgus measurements during 60°-90° cutting maneuvers, and good-to-excellent intra-rater and excellent inter-rater reliability for the 2D measurements in the present study supports the use of 2D knee valgus measurements in the evaluation of targeted interventions, although the limitations of examining cutting maneuvers using 2D measurement in complex movement still need to be considered. Level of Evidence: 3

Objective: To synthesize research literature, which has investigated the application of motor imagery and action observation in rehabilitation protocols. Specifically, we aimed to review the implementation of motor imagery and action observation in the rehabilitation of lower limb injuries. Methods: This scoping review followed Arksey and O’Malley's framework and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension guidelines for scoping reviews checklist. The Medline (PubMed), Cochrane Library, Scopus, and Web of Science databases were searched for controlled clinical trials published between 2010 and 2021 using key search terms. Primary articles were screened for inclusion based upon applying motor imagery and action observation as a rehabilitation protocol (independently or in combination) after sustaining an injury or undergoing surgery. Data were charted by extracting the exercise duration, frequency, and the number of weeks from the rehabilitative intervention protocols, and the measured clinical outcomes (pain, range of motion, muscle activity, and functional outcomes). Results: The initial database search resulted in 1367 articles, with 1352 excluded after screening, resulting in a total of 15 articles eligible for inclusion in the review. Six of the included articles included an action observation intervention, eight studies a motor imagery intervention, and a single study included combined motor imagery and action observation approach. The motor imagery and action observation techniques were able to improve clinical outcomes, including daily activity, functional movement, rage of motion, pain, and muscle strength. Conclusion: Motor imagery and action observation interventions may be effective to improve rehabilitative outcomes of lower limb injuries, thus its application should be considered alongside standard treatment protocols.