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Marker-Based Versus IMU-Based Kinematics for Estimates of Lumbar Spine Loads Using a Full-Body Musculoskeletal Model

Maria Prado, Sakiko Oyama, and Hugo Giambini

Musculoskeletal modeling, typically implemented using marker-based systems in laboratory environments, is commonly used for noninvasive estimations of loads. Inertial measurement units (IMUs) have become an alternative for the evaluation of kinematics. However, estimates of spine joint contact forces using IMUs have yet to be thoroughly evaluated. Dynamics tasks and static postures from activities of daily living were captured on 11 healthy subjects using both systems simultaneously. Spine kinematics obtained from IMU- and marker-based systems and L4–L5 joint contact forces were compared. Lateral bending resulted in a weak agreement with significant differences between the 2 systems (P = .02, average root mean-squared error = 4.81), whereas flexion–extension and axial rotation exhibited the highest agreement with no significant differences (P < .05, average root mean-squared error = 5.51 and P < .31, average root mean-squared error = 5.08, respectively). All tasks showed excellent correlations (R 2 = .76–.99) in estimated loads between systems. Differences in predicted loads at the L4–L5 were only observed during flexion–extension (1041 N vs 947 N, P = .0004) and walking with weights (814 N vs 727 N, P = .004). Different joint reaction force outcomes were obtained in 2 of the 8 tasks between systems, suggesting that IMUs can be robust tools allowing for convenient and less expensive evaluations and for longitudinal assessments inside and outside the laboratory setting.

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Characterizing Longitudinal Alterations in Postural Control Following Lower Limb Injury in Professional Rugby Union Players

Molly F. McCarthy-Ryan, Stephen D. Mellalieu, Holly Jones, Adam Bruton, and Isabel S. Moore

Assessment of player’s postural control following a lower limb injury is of interest to sports medicine practitioners due to its fundamental role in daily tasks and sporting activities. The aim was to longitudinally monitor professional rugby union players’ postural control during each phase of the rehabilitation program (acute, middle, and late) following a lower limb injury. Seven male rugby union players (height 1.80 [0.02] m; mass 100.3 [11.4] kg; age 24 [4] y) sustained a time loss, noncontact lower limb injury. Static postural control was assessed via sway path (in meters), and dynamic postural control was assessed via vertical postural stability index. Group differences (P < .05) were reported across the acute, middle, and late phase. Smaller magnitudes of sway path were observed for eyes-open sway path, and for the middle and late phase smaller magnitudes of vertical postural stability index (P < .05) at the end session compared with first session. Whereas larger magnitudes of vertical postural stability index were found between baseline and the last session (P < .05). Large interindividual and intraindividual variation was apparent across the 3 phases of rehabilitation. Postural control improvements were identified during rehabilitation. However, postural control did not return to baseline, with altered kinetics throughout each rehabilitation phase.

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Effect of Data and Gap Characteristics on the Nonlinear Calculation of Motion During Locomotor Activities

Arash Mohammadzadeh Gonabadi, Thad W. Buster, Guilherme M. Cesar, and Judith M. Burnfield

This study investigated how data series length and gaps in human kinematic data impact the accuracy of Lyapunov exponents (LyE) calculations with and without cubic spline interpolation. Kinematic time series were manipulated to create various data series lengths (28% and 100% of original) and gap durations (0.05–0.20 s). Longer gaps generally resulted in significantly higher LyE% error values in each plane in noninterpolated data. During cubic spline interpolation, only the 0.20-second gap in frontal plane data resulted in a significantly higher LyE% error. Data series length did not significantly affect LyE% error in noninterpolated data. During cubic spline interpolation, sagittal plane LyE% errors were significantly higher at shorter versus longer data series lengths. These findings suggest that not interpolating gaps in data could lead to erroneously high LyE values and mischaracterization of movement variability. When applying cubic spline, a long gap length (0.20 s) in the frontal plane or a short sagittal plane data series length (1000 data points) could also lead to erroneously high LyE values and mischaracterization of movement variability. These insights emphasize the necessity of detailed reporting on gap durations, data series lengths, and interpolation techniques when characterizing human movement variability using LyE values.

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Osteoarthritic Tibiofemoral Joint Contact Characteristics During Weightbearing With Arch-Supported and Standalone Lateral Wedge Insoles

Calvin T.F. Tse, Michael B. Ryan, Natasha M. Krowchuk, Alexander Scott, and Michael A. Hunt

Imbalanced joint load distribution across the tibiofemoral surface is a risk factor for osteoarthritic changes to this joint. Lateral wedge insoles, with and without arch support, are a form of biomechanical intervention that can redistribute tibiofemoral joint load, as estimated by external measures of knee load. The objective of this study was to examine the effect of these insoles on the internal joint contact characteristics of osteoarthritic knees during weightbearing. Fifteen adults with tibiofemoral osteoarthritis underwent magnetic resonance imaging of the affected knee, while standing under 3 insole conditions: flat control, lateral wedge alone, and lateral wedge with arch support. Images were processed, and the surface area and centroid location of joint contact were quantified separately for the medial and lateral tibiofemoral compartments. Medial contact surface area was increased with the 2 lateral wedge conditions compared with the control (P ≤ .012). A more anterior contact centroid was observed in the medial compartment in the lateral wedge with arch support compared with the lateral wedge alone (P = .009). Significant changes in lateral compartment joint contact outcomes were not observed. These findings represent early insights into how loading at the tibiofemoral interface may be altered by lateral wedge insoles as a potential intervention for knee osteoarthritis.

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Volume 40 (2024): Issue 3 (Jun 2024)

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Volume 18 (2024): Issue 2 (Jun 2024)

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Adapted Physical Activity Across the Life Span

Paul R. Malinowski, Paul H. Warner, and Wesley J. Wilson,

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Effects of Brief Mindfulness Training on Basketball Free-Throw Shooting Performance Under Pressure: A Randomized Controlled Trial of Dosage Response

Jessyca N. Arthur-Cameselle and Linda A. Keeler

Studies have indicated that as little as 15 min of mindfulness training (MT) positively affects sport performance under pressure, but the minimum amount of MT required to induce effects is unclear. The current experiment tested the effects of MT of different lengths on free-throw shooting under pressure. Forty-six participants (78% men) with competitive basketball experience completed pretest mindfulness and anxiety surveys and shot under low pressure. Using performance-based matched assignment, participants were randomly distributed into groups. On another day, participants completed audio trainings (6-min MT, 15-min MT, or control) and then shot under high pressure. Under high pressure, anxiety and mindfulness states did not differ among groups, nor were there group differences in average shooting percentage. However, only the control group performed worse on the second shot under high pressure compared with low pressure, suggesting possible protection effects of MT. Findings are discussed regarding application and possible interactions between traits, motivation, and incentive values.

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Mindfulness and Psychological Inflexibility in Portuguese Adolescent Athletes: A Novel Framework for Understanding the Link Between Shame and Sports Anxiety

Sara Margarida Simões de Oliveira, Marina Isabel Vieira Antunes Cunha, António Fernando Boleto Rosado, Mariana Saraiva, and Cláudia Rute Carlos Ferreira

This study aimed to test a comprehensive model in adolescent athletes that explores the effect of shame on sports anxiety and whether psychological inflexibility and mindfulness influence this association. The sample study included 210 young Portuguese athletes from different competitive sports. The path analysis results confirmed the adequacy of the proposed model, which explained 49% of the variance in sports anxiety. Results demonstrated that athletes who experienced higher levels of shame tended to exhibit elevated levels of sports anxiety through lower levels of mindfulness and higher psychological inflexibility. The study offers new empirical data that may be relevant for clinical and sport psychology practitioners. These findings seem to underline the importance of addressing shame and, consequently, sports anxiety in adolescent athletes by developing greater psychological flexibility and, inherently, more mindfulness skills among adolescent athletes who are in a phase of their lives where sport can play a crucial role.

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Special Olympics: Inclusion Debates and Equity in Sport, 1st Edition

Wonjun Choi and Sophia D. Min