Quantifying demands on the hamstrings during high-speed running: A systematic review and meta-analysis.

INTRODUCTION: Hamstring strain injury (HSI) remains a performance, economic, and player availability burden in sport. High-speed running (HSR) is cited as a common mechanism for HSI. While evidence exists regarding the high physical demands on the hamstring muscles in HSR, meta-analytical synthesis of related activation and kinetic variables is lacking. METHODS: A systematic search of Medline, Embase, Scopus, CINAHL, SportDiscus, and Cochrane library databases was conducted in accordance with the PRISMA 2020 guidelines. Studies reporting hamstring activation (electromyographic [EMG]) or hamstring muscle/related joint kinetics were included where healthy adult participants ran at or beyond 60% of maximum speed (activation studies) or 4 m per second (m/s) (kinetic studies). RESULTS: A total of 96 studies met the inclusion criteria. Run intensities were categorized as "slow," "moderate," or "fast" in both activation and kinetic based studies with appropriate relative, and raw measures, respectively. Meta-analysis revealed pooled mean lateral hamstring muscle activation levels of 108.1% (95% CI: 84.4%-131.7%) of maximal voluntary isometric contraction (MVIC) during "fast" running. Meta-analysis found swing phase peak knee flexion internal moment and power at 2.2 Newton meters/kilogram (Nm/kg) (95% CI: 1.9-2.5) and 40.3 Watts/kilogram (W/kg) (95% CI: 31.4-49.2), respectively. Hip extension peak moment and power was estimated as 4.8 Nm/kg (95% CI: 3.9-5.7) and 33.1 W/kg (95% CI: 17.4-48.9), respectively. CONCLUSIONS: As run intensity/speed increases, so do the activation and kinetic demands on the hamstrings. The presented data will enable clinicians to incorporate more objective measures into the design of injury prevention and return-to-play decision-making strategies.

A Pilot Longitudinal Study of 3-Dimensional Head and Neck Kinematics During Functional Tasks in Individuals With Chronic Idiopathic Neck Pain Either Wait-Listed for or Receiving Chiropractic Spinal Manipulative Therapy With Exercise.

OBJECTIVE: The purpose of this study was to determine if there is a relationship between pain and movement kinematics during functional tasks, evaluated over time, in individuals with chronic idiopathic neck pain. METHODS: Ten participants with chronic idiopathic neck pain performed 2 functional tasks (overhead reach to the right and putting on a seatbelt) while evaluated using 8 Oqus 300+ cameras. Kinematic variables included joint angles and range of motion (ROM) (°), head segment relative to neck segment (head-neck [HN]); and head/neck segment relative to upper thoracic segment (head/neck-trunk), velocity (m/s), and time (% of movement phase). Pain was quantified using a 100-mm visual analog scale. Linear mixed effects regression models were used to analyze associations between pain and kinematic variables adjusting for treatment group. RESULTS: For overhead reach, higher pain was associated with less HN peak rotation at baseline (ß = -0.33; 95% CI -0.52 to -0.14, P = .003) and less HN total rotation ROM at 6 months (ß = -0.19; 95% CI -0.38 to -0.003, P = .048). For the seatbelt task, higher pain was associated with less HN peak rotation (ß = -0.52; 95% CI -0.74 to -0.30 to -0.74, P < .001) and less HN total rotation ROM at baseline (ß = -0.32; 95% CI -0.53 to -0.10, P = .006). No other movement variables demonstrated meaningful relationships with pain for the reach or seatbelt tasks. CONCLUSION: Higher pain is associated with less HN peak and total rotation during functional reaching tasks requiring head rotation. Recognizing altered functional kinematics in individuals with chronic neck pain may assist patient management.

The impact of previous musculoskeletal injury on running gait variability: A systematic review.

BACKGROUND: Growing evidence suggests that identifying movement variability alterations in pathological vs. healthy gait may further understanding of injury mechanisms related to gait biomechanics; however, in the context of running and musculoskeletal injuries the role of movement variability remains unclear. RESEARCH QUESTION: What is the impact of a previous musculoskeletal injury on running gait variability? METHODS: Medline, CINAHL, Embase, Cochrane library and SPORTDiscus were searched from inception until February 2022. Eligibility criteria were (a) included a musculoskeletal injury group, (b) compared running biomechanics data to a control group, (c) measured movement variability for at least one dependent variable, (d) provided a statistical between-group comparison of variability outcomes. Exclusion criteria were neurological conditions impacting gait, upper body musculoskeletal injuries and age < 18 years old. A summative synthesis was performed instead of a meta-analysis due to methodological heterogeneity. RESULTS: Seventeen case-control studies were included. The most common deviations in variability observed among the injured groups were: (1) high and low knee-ankle/foot coupling variability and (2) low trunk-pelvis coupling variability. Significant (p < 0.05) between-group differences in movement variability were identified in 8 of 11; 73% of studies of runners with injury-related symptoms, and 3 of 7; 43% of studies of recovered or asymptomatic populations. SIGNIFICANCE: This review identified limited to strong evidence that running variability is altered in adults with a recent history of injury for specific joint couplings only. Individuals with ankle instability or pain employed altered running strategies more often than those who have recovered from injury. Altered variability strategies have been proposed to contribute to future running-related injuries, therefore these findings are relevant to clinicians managing active populations.

Is subject-specific musculoskeletal modelling worth the extra effort or is generic modelling worth the shortcut?

The majority of musculoskeletal modelling studies investigating healthy populations use generic models linearly scaled to roughly match an individual's anthropometry. Generic models disregard the considerable variation in musculoskeletal geometry and tissue properties between individuals. This study investigated the physiological implications of personalizing musculoskeletal model geometry (body segment mass, inertia, joint center, and maximum isometric muscle force). Nine healthy athletes performed ten repetitions of 15 meter sprints at 75-95% of their maximum sprinting speed and ten repetitions of unanticipated sidestep cut trials with a 4.5-5.5 m/s approach running speed. Structural magnetic resonance imaging was collected on the lower extremities, from which subject-specific musculoskeletal models were developed. A one-dimensional statistical parametric mapping paired t-test was used to compare generic and subject-specific musculoskeletal models for: lower-limb kinematics, kinetics, torque matching, as well as hamstrings, adductors, and quadriceps muscle activations and fiber dynamics. Percentage change of geometric parameters between generic and subject-specific models were determined. Compared to generic models, subject-specific models showed significantly lower ankle dorsi/plantar flexion angle during sprinting and several significantly different net joint moments during sprint and cut tasks. Additionally, subject-specific models demonstrated better torque matching, more physiologically plausible fiber lengths, higher fiber velocities, lower muscle forces, and lower simulated activations in a subset of investigated muscles and motor tasks. Furthermore, subject-specific models identified between-limb differences that were not identified with generic models. Use of subject-specific modeling, even in healthy populations, may result in more physiologically plausible muscle fiber mechanics. Implementing subject-specific models may be especially beneficial when investigating populations with substantial geometric between-limb differences, or unilateral musculoskeletal pathologies, as these are not captured by a generic model.

Male basketball players who report hip and groin pain perceive its negative impact both on- and off-court: A cross-sectional study.

OBJECTIVES: To identify if basketball players aged <20 years (U20) self-report hip and/or groin pain and if they perceive this as a problem. To determine potential differences in self-reported playing (training and match play) loads and Copenhagen Hip and Groin Outcome Score (HAGOS) between those with and without hip/groin pain. DESIGN: Cross-sectional. METHODS: Fifty-one pre-elite (state/national representative level) male U20 basketball players (Australian n=38; Italian n=13) self-reported current/historical hip/groin 'discomfort/pain' and 'problems', and playing loads. A two-factor regression model was fitted including main effects for hip/groin pain and Cohort and their interaction, with outcome variables playing loads and HAGOS subscale scores and dependent variable hip/groin pain. RESULTS: Twenty-one players (41%) self-reported hip/groin 'discomfort/pain', of which nine perceived no 'problems'. Two of these nine players reported training/playing time loss due to pain. Those self-reporting hip/groin discomfort/pain scored lower than those without in HAGOS subscales Symptoms (mean difference in score 8.94; 95%CI -25.24, -5.97), Pain (5.00; -16.42, -2.81), Function in daily living (0.00; -26.72 to -5.59), Function in sport and recreation (6.25; -21.24, -5.33), and hip and/or groin Quality of Life (5.00; -28.63, -8.10), indicating worse hip/groin problems. Participation subscale scores were different only for Italian players (36.25; -51.25, -20.00), with players self-reporting hip/groin discomfort/pain scoring lower. CONCLUSION: Most players who perceive both hip/groin 'discomfort/pain' and 'problems' also report training/playing time loss, suggesting players' perceptions of problematic symptoms and time-loss are associated. Adolescent basketball players perceive hip/groin pain to negatively impact their daily lives and sporting function.