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Recent research indicates that distance running stride-to-stride variability (SSV) is related to performance and injury. Previous studies have primarily focused on stride characteristics (stride length and time). We assessed SSV for sagittal plane joint angles with the primary purpose of testing for significant differences among the lower body joints. The secondary purpose was to determine if strong correlations exist among joint SSV measures. Thirty recreational adult runners participated in the study (8 females, 22 males, 39 ± 10 years; 53.1 ± 25.7 km/week). A 6-camera motion capture system (200 Hz) collected kinematic data during treadmill running at a preferred pace. A 2 by 3 repeated measures factorial ANOVA (phase—stance, swing; joint—hip, knee, ankle) was run (p = 0.05). There was a significant interaction effect (p < 0.001) and post hoc analysis revealed knee swing to be the most variable condition by far. For all three joints, there were strong correlations between stance and swing SSV (r = 0.80 to r = 0.88) and correlations among the joints were moderate to strong (r = 0.55 to 0.86). This study helps to better understand the joints/phases that contribute most to variability in the overall stride. Also, the strong correlations suggest that runners appear to have an overall SSV pattern that is similar across joints/phases. [ABSTRACT FROM AUTHOR]

The ankle, knee, and hip joints work together in the sagittal plane to absorb landing forces. Reduced sagittal plane motion at the ankle may alter landing strategies at the knee and hip, potentially increasing injury risk; however, no studies have examined the kinematic relationships between the joints during jump landings. Healthy adults (N = 30; 15 male, 15 female) performed jump landings onto a force plate while three-dimensional kinematic data were collected. Joint displacement values were calculated during the loading phase as the difference between peak and initial contact angles. No relationship existed between ankle dorsiflexion displacement during landing and three-dimensional knee and hip displacements. However, less ankle dorsiflexion displacement was associated with landing at initial ground contact with larger hip flexion, hip internal rotation, knee flexion, knee varus, and smaller plantar flexion angles. Findings of the current study suggest that restrictions in ankle motion during landing may contribute to contacting the ground in a more flexed position but continuing through little additional motion to absorb the landing. Transverse plane hip and frontal plane knee positioning may also occur, which are known to increase the risk of lower extremity injury. [ABSTRACT FROM AUTHOR]

Objective: To determine the association between selected biomechanical variables and risk of patellofemoral pain (PFP) in males and females. Design: Prospective cohort. Setting: US Service Academies. Participants: Four thousand five hundred fortythree cadets (1727 females and 2816 males). Assessment of risk factors: Three-dimensional biomechanics during a jumplanding task, lower-extremity strength, Q-angle, and navicular drop. Main outcome measures: Cadets were monitored for diagnosis of PFP during their enrollment in a service academy. Three-dimensional hip and knee kinematic data were determined at initial contact (IC) and at 50% of the stance phase of the jump-landing task. Logistic regression analyses were performed for each risk factor variable in males and females (P<0.05). Results: Less than 10 degrees of hip abduction at IC [odds ratio (OR)=1.86, P =0.03] and greater than 10 degrees of knee internal rotation at 50% of the stance phase (OR=1.71, P=0.02) increased the risk of PFP in females. Greater than 20 degrees of knee flexion at IC (OR = 0.47, P < 0.01) and between 0 and 5 degrees of hip external rotation at 50% of the stance phase (OR = 0.52, P = 0.04) decreased the risk of PFP in males. No other variables were associated with risk of developing PFP (P < 0.05). Conclusions: The results suggest males and females have differing kinematic risk factor profiles for the development of PFP. Clinical relevance: To most effectively reduce the risk of developing PFP, the risk factor variables specific to males (decreased knee flexion and increased hip external rotation) and females (decreased hip abduction and increased knee internal rotation) should be addressed in injury prevention programs. [ABSTRACT FROM AUTHOR]

Objective: To present recommendations for athletic trainers and other health care providers regarding the identification of risk factors for and management of individuals with patellofemoral pain (PFP). Background: Patellofemoral pain is one of the most common knee diagnoses; however, this condition continues to be one of the most challenging to manage. Recent evidence has suggested that certain risk factors may contribute to the development of PFP. Early identification of risk factors may allow clinicians to develop and implement programs aimed at reducing the incidence of this condition. To date, clinicians have used various treatment strategies that have not necessarily benefitted all patients. Suboptimal outcomes may reflect the need to integrate clinical practice with scientific evidence to facilitate clinical decision making. Recommendations: The recommendations are based on the best available evidence. They are intended to give athletic trainers and other health care professionals a framework for identifying risk factors for and managing patients with PFP. [ABSTRACT FROM AUTHOR]

The article examines maturation and sex differences in neuromuscular characteristics of youth Athletes. Three electromagnetic sensors were placed and secured to the subjects' dominant anteromedial tibia, lateral thigh, and sacrum. The results show how young athletes may also benefit from additional strength training for the glutes and quadriceps to enhance their ability to properly decelerate during landings and sports-specific tasks.

The article presents the findings of a cross-sectional study which determines the relationship between lower extremity muscle activity and knee-flexion angle during a jump-landing task. The study showed that the vastus lateralis (VL) and vastus medialis oblique (VMO activity predicted 49.5% of the variance in knee-flexion displacement. It revealed that small knee-flexion angles were influenced by high quadriceps.