Search Results

Total knee arthroplasty (TKA) surgery improves knee joint kinematics and kinetics during gait for most patients, but a lack of evidence exists for the level and incidence of improvement that is achieved. The objective of this study was to quantify patient-specific improvements in knee biomechanics relative to osteoarthritis (OA) severity levels. Seventy-two patients underwent 3-dimensional (3D) gait analysis before and 1 year after TKA surgery, as well as 72 asymptomatic adults and 72 with moderate knee OA. A combination of principal component analysis and discriminant analyses were used to categorize knee joint biomechanics for patients before and after surgery relative to asymptomatic, moderate, and severe OA. Post-TKA, 63% were categorized with knee biomechanics consistent with moderate OA, 29% with severe OA, and 8% asymptomatic. The magnitude and pattern of the knee adduction moment and angle (frontal plane features) were the most significant contributors in discriminating between pre-TKA and post-TKA knee biomechanics. Standard of care TKA improves knee biomechanics during gait to levels most consistent with moderate knee OA and predominately targets frontal plane features. These results provide evidence for the level of improvement in knee biomechanics that can be expected following surgery and highlight the biomechanics most targeted by surgery.

The purpose of this study was to investigate youth athletes’ perceptions of group norms for competition, practice, and social setting contexts in relation to personal and social factors. A secondary purpose of this study was to examine the interactions of the personal and situation factors on perceptions of group norms. Participants included 424 athletes from 35 high school sport teams who completed a survey assessing team norms in competition, practice, and social settings. Multilevel analysis results revealed differences in group norms by gender as well as gender by team tenure and gender by sport type interactions. Female teams held higher perceptions of norms for competition, practice, and social settings than male teams. Interactions between gender and team tenure and gender and sport type revealed significant differences in practice norms. No differences were found in norms by group size. The findings suggest that examining the characteristics of the team members (i.e., gender, team tenure) and team (i.e., type of sport) may enhance our understanding of group norms in a youth sport setting.

The mental health of young people is of increasing concern, and early intervention prevention strategies are required. Youth sports are potentially effective environments within which to situate interventions due to high participation rates, familiarity to young participants, and the typically positive relationships held with adults within such spaces. However, coaches identify that they require more knowledge to better respond to mental health concerns that may be present among players. Here, we describe a research translation process in which an open-access, evidence-informed resource was developed to support coaches and sports clubs to better respond to athletes in need as well as to create environments that may protect against mental ill-health and promote well-being. The resource includes a toolkit—with an associated checklist—for recreational sport clubs to follow, a guide to responding to young people in need, and a short educational video. We suggest that these practical and applied resources, which can be immediately implemented, may assist in the provision of targeted and structured guidance for coaches’ first response intervention with vulnerable young people. Furthermore, these resources can support future efforts by being specifically tailored for the unique locations and cultures that vary among youth sport environments.

Background: The purpose of this scoping review was to critically examine the design and quality of contemporary research involving college student physical activity participation, focusing on physical activity measurement, assessment of sociodemographic characteristics, and examination of inequities based on sociodemographic characteristics. Methods: Systematic searches were conducted in 4 electronic databases. Results: From 28,951 sources screened, data were extracted from 488 that met the inclusion criteria. The majority of the studies were cross-sectional in design (91.4%) and employed convenience sampling methods (83.0%). Based on the subsample of studies that reported the percentage of students meeting aerobic (n = 158; equivalent of 150 min/wk of moderate physical activity) and muscle-strengthening activity recommendations (n = 8; ≥2 times/wk), 58.7% and 47.8% of students met aerobic and muscle-strengthening recommendations, respectively. With the exception of age and sex, sociodemographic characteristics were rarely assessed, and inequities based upon them were even more scarcely examined—with no apparent increase in reporting over the past decade. Conclusions: College student physical activity levels remain concerningly low. The generalizability of findings from the contemporary literature is limited due to study design, and acknowledgement of the influence that sociodemographic characteristics have on physical activity has largely been overlooked. Recommendations for future research directions and practices are provided.

Knee osteoarthritis is thought to result, in part, from excessive and unbalanced joint loading. Toe-in and toe-out gait modifications produce alterations in external knee joint moments, and some improvements in pain over the short- and long-term. The aim of this study was to probe mechanisms of altered joint loading through the assessment of tibiofemoral contact in standing with toe-in and toe-out positions using an open magnetic resonance scanner. In this study, 15 young, healthy participants underwent standing magnetic resonance imaging of one of their knees in 3 foot positions. Images were analyzed to determine contact in the tibiofemoral joint, with primary outcomes including centroid of contact and contact area for each compartment and overall. The centroid of contact shifted laterally in the lateral compartment with both toe-in and toe-out postures, compared with the neutral position (P < .01), while contact area in the medial and lateral compartments showed no statistical differences. Findings from this study indicate that changes in the loading anatomy are present in the tibiofemoral joint with toe-in and toe-out and that a small amount of lateralization of contact, especially in the lateral compartment, does occur with these altered lower limb orientations.

As the biologically active component of glucose tolerance factor (GTF), the essential trace mineral chromium is now being marketed to athletes. GTF potentiates insulin activity and is responsible for normal insulin function. Thus, insulin's effects on carbohydrate, fat, and protein metabolism are dependent upon the maintenance of adequate chromium stores. Due to excessive chromium loss and marginal chromium intake, athletes may have an increased requirement for chromium. Therefore, in some circumstances the dietary supplementation of a chromium compound may be efficacious. The restoration and maintenance of chromium stores via supplementation would promote optimal insulin efficiency, necessary for high-level athletic performance. However, potential anabolic effects of enhanced insulin function would likely be marginal, and reports of short-term anabolic increases from the supplementation of an organic chromium compound need to be confirmed.

Background: The ability to objectively assess physical activity and inactivity in free living individuals is important in understanding activity patterns and the dose response relationship with health. Currently, a large number of research tools exist, but little evidence has examined the validity/utility of the Research Tracker 6 (RT6) monitor. Questions remain in regard to the best placements, positions, and cut-points in young adults to determine activity intensity across a range of activities. This study sought to address this gap in young adults. The study aims were 1) to examine criterion validity of RT6 in comparison to breath-by-breath gas analysis; 2) convergent validity of RT6 in comparison to ActiGraph and GENEActiv; 3) development of RT6 tri-axial vector magnitude cut-points to classify physical activity at different intensities (i.e., for sedentary, moderate, and vigorous); 4) to compare the generated cut-points of the RT6 in comparison to other tools. Methods: Following ethics approval and informed consent, 31 young adults (age = 22±3 years: BMI = 23±3 kg/m²) undertook five modes of physical activity/sedentary behaviors while wearing three different accelerometers at hip and wrist locations (ActiGraph GT9X Link, GENEActiv, RT6). Expired gas was sampled during the five activities (MetaMax 3B). Correlational analysis assessed the relationship between accelerometer devices and METs/VO₂. Receiver Operating Characteristic Curves analysis were used to calculate area under the curve and define cut-points for physical activity intensities. Results: The RT6 demonstrated criterion and convergent validity (r = 0.662–0.966, P < .05). RT6 generally performed good to excellent across activity intensities and monitor position (sedentary [AUC = 0.862–0.911], moderate [AUC = 0.849–0.830], vigorous [AUC = 0.872–0.877]) for non-dominant and dominant position, respectively. Cut-points were derived across activity intensities for non-dominant- and dominant-worn RT6 devices. Comparison of the RT6 derived cut-points identified appropriate agreement with comparative tools but yields the strongest agreement with the ActiGraph monitor at the hip location during sedentary, light, and moderate activity. Conclusion: The RT6 performed similar to the ActiGraph and GENEActiv and is capable of classifying the intensity of physical activity in young adults. As such this may offer a more useable tool for understanding current physical activity levels and in intervention studies to monitor and track changes without the excessive need for downloading and making complex analysis, especially given the option to view energy expenditure data while wearing it. The RT6 should be placed on the dominant hip when determining activities that are sedentary, moderate, or vigorous intensity.

Context: The Y Balance Test was developed as a test of dynamic postural control and has been shown to be predictive of lower-extremity injury. However, the relationship between hip strength and performance on the Y Balance Test has not been fully elucidated. Objective: The goal of this study was to identify the relationship between components of isometric hip strength and the Y Balance Test, to provide clinicians better guidance as to specific areas of muscle performance to address in the event of poor performance on the Y Balance Test. Design: Laboratory study. Setting: Biomechanics laboratory. Participants: A total of 73 healthy participants (40 males and 33 females) volunteered for this study. Intervention: None. Main Outcome Measures: Participants completed the Y Balance Test on the right leg. The authors then measured peak isometric torque in hip external rotation, abduction, and extension. Correlations were calculated between torque measurements, normalized for mass and Y Balance Test performance. Significant relationships were used in linear regression models to determine which variables were predictive of the Y Balance Test performance. Results: The authors found significant positive correlations between Y Balance Test performance and hip abduction strength. They also found correlations between the Y Balance Test and hip extension and external rotation strengths. Linear regression analysis showed hip abduction to be the only significant predictor of Y Balance performance. Conclusions: The authors found the strongest association between the Y Balance Test and hip abduction strength. They also showed smaller but significant associations with hip extension and external rotation strength. When entered into a linear regression analysis, hip abduction strength was the only significant predictor of Y Balance performance. Using this information, practitioners should look to hip abduction strength when patients exhibit deficits in the Y Balance Test.