RESUMO
OBJECTIVES: The current study investigated performance fatigability (PF) and time course of changes in force, electromyographic amplitude (EMG AMP) and frequency (EMG MPF), and neuromuscular efficiency (NME) during a sustained, isometric, handgrip hold to failure (HTF) using the rating of perceived exertion (RPE)-Clamp Model. METHODS: Twelve males performed a handgrip HTF anchored to RPE=5. The time to task failure (Tlim), force (N), EMG AMP and MPF, and NME (normalized force/ normalized EMG AMP) were recorded. Analyses included a paired samples t-test for PF at an alpha of p<0.05, 1-way repeated measures ANOVA across time and post-hoc t-tests (p<0.0025) for force, EMG AMP and MPF, and NME responses. RESULTS: The PF (pre- to post- maximal force % decline) was 38.2±11.5%. There were decreases in responses, relative to 0% Tlim, from 40% to 100% Tlim (force), at 30%, 60%, and 100% Tlim (EMG AMP), from 10% to 100% Tlim(EMP MPF), and from 50% to 65%, and 80% to 100% Tlim (NME) (p<0.0025). CONCLUSIONS: The RPE-Clamp Model in this study demonstrated that pacing strategies may be influenced by the integration of anticipatory, feedforward, and feedback mechanisms, and provided insights into the relationship between neuromuscular and perceptual responses, and actual force generating capacity.
Assuntos
Eletromiografia , Força da Mão , Fadiga Muscular , Músculo Esquelético , Humanos , Masculino , Força da Mão/fisiologia , Fadiga Muscular/fisiologia , Adulto Jovem , Adulto , Eletromiografia/métodos , Músculo Esquelético/fisiologia , Contração Isométrica/fisiologia , Esforço Físico/fisiologiaRESUMO
OBJECTIVE: People with Marfan syndrome (MFS) have clinical symptoms of hip pain, but to date, there is limited knowledge about hip-related structural abnormalities in these patients. Therefore, the purpose of this cross-sectional study was to assess hip-related structural abnormalities and patient-reported outcomes (PRO) in a cohort of patients with MFS compared to healthy controls. METHODS: Nineteen individuals with MFS (17 females, 39.8±11.5 years) and 19 age, sex, and body mass index-matched healthy, asymptomatic individuals (17 females, 36.2±12.5 years) underwent radiographic imaging and unilateral hip MRI. The Scoring Osteoarthritis with MRI (SHOMRI) technique was used to assess hip-related morphological abnormalities between the MFS and control groups. All participants completed the Hip disability and Osteoarthritis Outcome Score (HOOS) to assess hip-related symptoms, pain, and function during activities of daily living (ADL) and quality of life (QOL). RESULTS: The MFS group exhibited higher lateral center edge angles (p < .001). Despite similar severity of femoral cartilage damage (p = 1.0), the MFS group exhibited a higher severity (p = 0.046) of acetabular cartilage degeneration (1.21±1.08) compared to the controls (0.53±1.02). There were no between-group differences in severity of labral pathology, subchondral cysts, or edema. Individuals with MFS also self-reported significantly lower HOOS symptoms (p = 0.003), pain (p = 0.014), ADL (p = 0.028), and QOL (p = 0.014) sub-scores, indicating worse hip-related PRO in MFS. CONCLUSION: Our study results suggest that individuals with MFS exhibit early signs of acetabular cartilage degeneration and poor hip-related clinical outcomes compared to healthy individuals. Future work should investigate the underlying biomechanical mechanisms associated with hip joint degeneration in the MFS population.
RESUMO
ABSTRACT: Ramirez, VJ, Bazrgari, B, Spencer, A, Gao, F, and Samaan, MA. Influence of repetitions-to-failure deadlift on lumbo-pelvic coordination, with and without body armor. J Strength Cond Res XX(X): 000-000, 2024-Repetition-to-failure (RTF) deadlift is a training modality for building lifting capacity that is often implemented by service members to maintain a minimum level of physical fitness. Despite its physiological benefits, little is known about the effects of RTF on the biomechanics of lumbar spine. Additionally, the effects of heavy deadlift training with body armor are unknown. The aim of this study was to investigate the effects of RTF deadlift on lumbo-pelvic coordination and posture, with and without body armor. Twenty-three healthy subjects, recreational powerlifters, were recruited for this study. Kinematics of the trunk and pelvis were measured using a 3D motion capture system while subjects conducted RTF deadlifts with a 68-kg low-handle hexagonal bar with and without a simulated body armor (22.68 kg). Lumbo-pelvic coordination was characterized using a vector coding approach and coupling angle variability (CAV) using circular statistics, over 3 equally divided segments of the lifting phase. More specifically, the coupling angle values were used to determine the coordination pattern between the thorax and pelvis. Trunk and pelvis ranges of motion and the amount of in-phase lumbo-pelvic coordination pattern increased with RTF deadlift. Additionally, CAV of the first and the third segments of deadlift cycle increased with RTF deadlift. Increase in variability of lumbo-pelvic coordination and peak trunk flexion (i.e., indication of increased mechanical demand of lifting on the spine), as a result of RTF deadlifting, can have deleterious soft tissue responses and contribute to an increase in risk of lower back injury.
RESUMO
ABSTRACT: Kwak, M, Succi, PJ, Benitez, B, Mitchinson, C, Samaan, MA, Abel, MG, and Bergstrom, HC. Comparison of force, neuromuscular, and metabolic responses during sustained, isometric handgrip holds to failure anchored to low and high perceptual intensities in men: An exploratory study. J Strength Cond Res 38(8): e405-e416, 2024-This study examined the responses of force alterations, relative to critical force (CF), neuromuscular parameters, and muscle oxygenation (SmO2) for isometric handgrip holds to failure (HTF) anchored to ratings of perceived exertion (RPE) of 3 and 7. Twelve men completed pre-maximal voluntary isometric contractions (pre-MVIC), submaximal HTF at 4 percentages of pre-MVIC, HTF at RPE = 3 and 7, and post-MVIC. Mechanomyograpic (MMG) signals and SmO2 were recorded during the RPE HTF. Analyses included paired-samples t-tests and repeated-measures ANOVAs at an alpha level of p ≤ 0.05. Time to task failure was not different between RPE 3 (478.7 ± 196.6 s) and RPE 7 (495.8 ± 173.8 s). Performance fatigability (PF) and MMG amplitude (AMP) were greater for RPE 7 (PF: 37.9 ± 12.9%; MMG AMP: 15.7 ± 7.4% MVIC) than RPE 3 (PF: 30.0 ± 14.5%; MMG AMP: 10.2 ± 6.5% MVIC), but MMG mean power frequency (MPF) was greater for RPE 3 (146.2 ± 31.1% MVIC) than RPE 7 (128.8 ± 23.0% MVIC). There were RPE-dependent decreases in force (p ≤ 0.01) across 3 discernable phases during the HTF. There were decreases in MMG AMP across time for both RPEs, but there were no significant changes in MMG MPF or SmO2. There were overall similar motor unit control strategies and local metabolic demand between RPEs. The majority of the HTF performed below CF at RPE 3 and 7 indicated CF did not reflect the highest sustainable force. When prescribing isometric exercise anchored to RPE, practitioners should be aware of the magnitude of force loss and relative intensity of the task to be sure desired training loads are met.
Assuntos
Força da Mão , Contração Isométrica , Músculo Esquelético , Humanos , Masculino , Força da Mão/fisiologia , Contração Isométrica/fisiologia , Adulto Jovem , Músculo Esquelético/fisiologia , Adulto , Esforço Físico/fisiologia , Consumo de Oxigênio/fisiologia , Fadiga Muscular/fisiologia , EletromiografiaRESUMO
OBJECTIVE: To determine the longitudinal changes of patellofemoral joint (PFJ) contact pressure following anterior cruciate ligament reconstruction (ACLR). To identify the associations between PFJ contact pressure and cartilage health. DESIGN: Forty-nine subjects with hamstring autograft ACLR (27 males; age 28.8 [standard deviation, 8.3] years) and 19 controls (12 males; 30.7 [4.6] years) participated. A sagittal plane musculoskeletal model was used to estimate PFJ contact pressure. A combined T1ρ/T2 magnetic resonance sequence was obtained. Assessments were performed preoperatively, at 6 months, 1, 2, and 3 years postoperatively in ACLR subjects and once for controls. Repeated Analysis of Variance (ANOVA) was used to compare peak PFJ contact pressure between ACLR and contralateral knees, and t-tests to compare with control knees. Statistical parametric mapping was used to evaluate the associations between PFJ contact pressure and cartilage relaxation concurrently and longitudinally. RESULTS: No changes in peak PFJ contact pressure were found within ACLR knees over 3 years (preoperative to 3 years, 0.36 [CI, -0.08, 0.81] MPa), but decreased over time in the contralateral knees (0.75 [0.32, 1.18] MPa). When compared to the controls, ACLR knees exhibited lower PFJ contact pressure at all time points (at baseline, -0.64 [-1.25, -0.03] MPa). Within ACLR knees, lower PFJ contact pressure at 6 months was associated with elevated T2 times (r = -0.47 to -0.49, p = 0.021-0.025). CONCLUSIONS: Underloading of the PFJ following ACLR persists for up to 3 years and has concurrent and future consequences in cartilage health. The non-surgical knees exhibited normal contact pressure initially but decreased over time achieving limb symmetry.
Assuntos
Lesões do Ligamento Cruzado Anterior , Cartilagem Articular , Articulação Patelofemoral , Masculino , Humanos , Adulto , Articulação Patelofemoral/diagnóstico por imagem , Articulação do Joelho/diagnóstico por imagem , Articulação do Joelho/cirurgia , Autoenxertos , Joelho , Cartilagem Articular/cirurgia , Imageamento por Ressonância Magnética , Lesões do Ligamento Cruzado Anterior/cirurgiaRESUMO
BACKGROUND: Diffusion tensor imaging (DTI) parameters correlate with muscle fiber composition, but it is unclear how these relate to in vivo contractile function. PURPOSE: To determine the relationship between DTI parameters of the vastus lateralis (VL) and in vivo knee extensor contractile. METHODS: Thirteen healthy, premenopausal women underwent magnetic resonance imaging of the mid-thigh to determine patellar tendon moment arm length and quadriceps cross-sectional area. Fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) of the VL were determined using diffusion tensor imaging (DTI). Participants underwent an interpolated twitch (ITT) experiment before and after a fatiguing concentric-eccentric isokinetic knee extension (60°·s-1 ). During the ITT, supramaximal electrical stimuli were delivered to elicit twitch responses from the knee extensors before, during, and after a maximal voluntary isometric contraction (MVIC). Knee extensor-specific tension during twitch and MVIC were calculated from isometric torque data. Pearson's correlations were used to determine the relationship between muscle contractile properties and DTI parameters. RESULTS: MD and RD were moderately correlated with peak twitch force and rate of force development. FA and AD were moderately inversely related to percent change in MVIC following exercise. CONCLUSION: MD and RD are associated with in vivo quadriceps twitch properties but not voluntary strength, which may reflect the mechanical properties of constituent fiber types. FA and AD appear to relate to MVIC strength following fatiguing exercise.
Assuntos
Músculo Esquelético , Músculo Quadríceps , Humanos , Feminino , Músculo Quadríceps/diagnóstico por imagem , Músculo Quadríceps/fisiologia , Músculo Esquelético/fisiologia , Imagem de Tensor de Difusão , Contração Muscular/fisiologia , Joelho/fisiologia , Contração Isométrica/fisiologia , TorqueRESUMO
Joint coordination variability during walking that is associated with patellofemoral joint cartilage degeneration after anterior cruciate ligament reconstruction are not well understood. The purpose of this study was to assess between-limb differences in joint coordination variability and to determine the relationship of coordination variability with postoperative patellofemoral joint cartilage composition. Thirty-five patients underwent bilateral gait analysis and a magnetic resonance exam of the reconstructed knee joint at 6 months post anterior cruciate ligament reconstruction. Vector coding was used to assess coordination variability during the early (1%-33%), mid (34%-66%), and late (67%-100%) stance phase. The T1ρ/T2 mapping was used to evaluate the glycosaminoglycan-collagen matrix of the patellar and femoral trochlear cartilage. Compared with the uninjured limb, the reconstructed limb exhibited higher hip sagittal/knee sagittal plane coordination variability during midstance as well as higher knee sagittal/ankle sagittal plane coordination variability during both mid and late stance. The hip sagittal/knee sagittal plane coordination variability during midstance predicted 14.6% of the variance in patellar cartilage T1ρ values within the reconstructed limb. In addition, sex of participants was able to predict 32.4% and 13.7% of the variance in femoral trochlea T1ρ and T2 values, respectively. The study results demonstrate that a multijoint mechanism may be associated with early patellofemoral joint cartilage degeneration at 6 months after anterior cruciate ligament reconstruction.
Assuntos
Lesões do Ligamento Cruzado Anterior , Reconstrução do Ligamento Cruzado Anterior , Cartilagem Articular , Articulação Patelofemoral , Humanos , Articulação do Joelho/cirurgia , Imageamento por Ressonância Magnética , Articulação Patelofemoral/diagnóstico por imagem , Articulação Patelofemoral/cirurgiaRESUMO
PURPOSE: To validate SHOMRI gradings in preoperative hip magnetic resonance imaging (MRI) with intra-arthroscopic evaluation of intraarticular hip abnormalities. METHODS: Preoperative non-arthrographic 3.0-T MRIs of 40 hips in 39 patients (1 patient with bilateral hip surgery) with femoroacetabular impingement (FAI) syndrome (mean age, 34.7 years ± 9.0; n = 16 females), refractory to conservative measures, that underwent hip arthroscopy were retrospectively assessed by two radiologists for chondrolabral abnormalities and compared with intra-arthroscopic findings as the standard of reference. Arthroscopically accessible regions were compared with the corresponding SHOMRI subregions and assessed for the presence and grade of cartilaginous pathologies in the acetabulum and femoral head. The acetabular labrum was assessed for the presence or absence of labral tears. For the statistical analysis sensitivity and specificity as well as intraclass correlation (ICC) for interobserver agreement were calculated. RESULTS: Regarding chondral abnormalities, 58.8% of the surgical cases showed chondral defects. SHOMRI scoring showed a sensitivity of 95.7% and specificity of 84.8% in detecting cartilage lesions. Moreover, all cases with full-thickness defects (n = 9) were identified correctly, and in n = 6 cases (out of n = 36 with partial-thickness defects) the defective cartilage was identified but the actual depth overestimated. Labral tears were present in all cases and the MR readers identified 92.5% correctly. ICC showed a good interobserver agreement with 86.3% (95% CI 80.0, 90.6%) CONCLUSION: Using arthroscopic correlation, SHOMRI grading of the hip proves to be a reliable and precise method to assess chondrolabral hip joint abnormalities. KEY POINTS: ⢠Assessment of hip abnormalities using MRI with surgical correlation. ⢠Comparing surgery and MRI by creating a hybrid anatomic map that covers both modalities. ⢠Non-arthrographic use of 3.0-T MRI provides detailed information on cartilage and labral abnormalities in hip joints.
Assuntos
Artroscopia/métodos , Articulação do Quadril/patologia , Imageamento por Ressonância Magnética/métodos , Osteoartrite do Quadril/diagnóstico , Adolescente , Adulto , Cartilagem Articular/patologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Valores de Referência , Reprodutibilidade dos Testes , Índice de Gravidade de DoençaRESUMO
PURPOSE: To investigate the longitudinal changes in landing mechanics and knee kinematics for patients both before and 3 years after anterior cruciate ligament reconstruction (ACLR) and to investigate the association between changes in landing mechanics and magnetic resonance knee kinematics. METHODS: Thirty-one ACLR patients were included in the study. All patients underwent magnetic resonance imaging and biomechanical analysis of a drop-landing task using the injured knee and contralateral knee preoperatively and at 6 months and 3 years after ACLR. For evaluations of knee joint anteroposterior laxity, tibial position was calculated using quantitative loaded magnetic resonance methods. RESULTS: The ACLR knee exhibited a significantly lower peak vertical ground reaction force and peak external knee flexion moment and angle at 6 months compared with the contralateral knee; however, the differences were resolved at 3 years. Tibial position was significantly more anterior on the injured side, and the side-to-side difference (SSD) in tibial position exhibited a significant increase from 6 months to 3 years. Among ACLR knees, a greater SSD in peak knee flexion moment at 6 months was associated with an increase in the SSD in anterior tibial translation from 6 months to 3 years. CONCLUSIONS: Although landing mechanics and clinical outcomes recovered in patients with ACLR in this study, anteroposterior translation failed to be restored at 3 years after surgery. In addition, patients who have low knee flexion moments in early stages could have greater anteroposterior laxity. CLINICAL RELEVANCE: Because of the adverse consequences of abnormal knee kinetics on anterior laxity after ACLR, efforts to improve knee movement patterns should be initiated.
Assuntos
Reconstrução do Ligamento Cruzado Anterior , Instabilidade Articular/fisiopatologia , Articulação do Joelho/diagnóstico por imagem , Articulação do Joelho/fisiopatologia , Imageamento por Ressonância Magnética , Adulto , Fenômenos Biomecânicos/fisiologia , Feminino , Humanos , Instabilidade Articular/diagnóstico por imagem , Instabilidade Articular/cirurgia , Articulação do Joelho/cirurgia , MasculinoRESUMO
PURPOSE: To investigate the changes in landing biomechanics over a 3-year period and their correlation with cartilage degenerative changes in the medial tibiofemoral joint of the knee after anterior cruciate ligament reconstruction (ACLR) using magnetic resonance T1ρ mapping. METHODS: Thirty-one anterior cruciate ligament-injured patients underwent magnetic resonance imaging of the injured knee before ACLR and 3 years after ACLR, as well as biomechanical analysis of a drop-landing task at 6 months and 3 years after ACLR. Sixteen healthy individuals were recruited and underwent knee magnetic resonance imaging and biomechanical assessment during a drop-landing task. T1ρ cartilage relaxation times were calculated for the medial femur and tibia. RESULTS: ACLR patients exhibited increased peak vertical ground reaction force (VGRF), VGRF impulse, peak knee flexion moment (KFM), and KFM impulse from 6 months to 3 years (P < .001 for each). Although the ACLR knees showed significantly lower peak VGRF and KFM at 6 months (P < .001 for both) when compared with the controls, there were no significant differences at 3 years. At 3 years, ACLR patients showed higher T1ρ values over the medial femur (P < .001) and tibia (P = .012) when compared with their preoperative values and with healthy control values. Within the ACLR group, side-to-side differences in peak VGRF and sagittal knee biomechanics at 6 months were associated with increased T1ρ values from baseline to 3 years. CONCLUSIONS: The results of this longitudinal study show that landing biomechanics are altered after ACLR but biomechanical abnormalities tend to recover at 3 years after ACLR. Differences in lower-extremity mechanics during a landing task at 6 months may be associated with cartilage degeneration at 3 years after anterior cruciate ligament injury and reconstruction. LEVEL OF EVIDENCE: Level II, prospective trial.
Assuntos
Lesões do Ligamento Cruzado Anterior/cirurgia , Reconstrução do Ligamento Cruzado Anterior/efeitos adversos , Adulto , Ligamento Cruzado Anterior/diagnóstico por imagem , Ligamento Cruzado Anterior/fisiopatologia , Ligamento Cruzado Anterior/cirurgia , Lesões do Ligamento Cruzado Anterior/diagnóstico por imagem , Reconstrução do Ligamento Cruzado Anterior/métodos , Fenômenos Biomecânicos , Estudos de Casos e Controles , Feminino , Humanos , Articulação do Joelho/diagnóstico por imagem , Articulação do Joelho/fisiopatologia , Articulação do Joelho/cirurgia , Estudos Longitudinais , Extremidade Inferior/fisiopatologia , Imageamento por Ressonância Magnética/métodos , Masculino , Complicações Pós-Operatórias/fisiopatologia , Estudos Prospectivos , Amplitude de Movimento Articular , Tíbia/fisiopatologia , Adulto JovemRESUMO
The study objective was to examine the effects of three days of sleep restriction on maximal jump performance and joint coordination. Eleven elite cyclists obtained a one-week baseline of habitual sleep then restricted sleep to 4 h/night (SR) for three nights assessed through self-report and actigraphy. Pre and post-intervention measures were a box drop maximal vertical jump with 3D motion capture to assess physical performance and biomechanical changes, and Psychomotor Vigilance Task (PVT) assessed changes in response time. Associations between biomechanical, physical, and cognitive performance measures were assessed. Participants restricted reported sleep from 7.4 ± 0.5 h/night at baseline to 4.0 ± 0.2 h/night and actigraphy indicated 6.7 ± 0.7 to 3.7 ± 0.2 h/night. Following SR, jump height decreased (0.44 ± 0.09 vs. 0.42 ± 0.10 m, p = 0.02, g = 0.21). Hip sagittal/knee frontal (Δ15.5°, p = 0.04, g = 0.40) and hip frontal/knee frontal (Δ11.0°, p < 0.01, g = 0.44) plane coordination variability increased after SR. Hip sagittal/knee frontal plane coordination variability after SR was associated with increasingly slower PVT response time (r = 0.63, p = 0.03). These findings suggest SR for three days decreased maximal jump performance. SR increased joint coordination variability and was associated with greater impairment in response time. SR leads to deviations from preferred movement patterns, which may have implications for decrements in athlete performance and increased injury risk.
Assuntos
Desempenho Atlético/fisiologia , Desempenho Psicomotor , Tempo de Reação , Sono , Actigrafia , Adulto , Atletas , Estudos Cross-Over , Humanos , MasculinoRESUMO
BACKGROUND: Osteoarthritis (OA) is a multifaceted disease with many variables affecting diagnosis and progression. Topological data analysis (TDA) is a state-of-the-art big data analytics tool that can combine all variables into multidimensional space. TDA is used to simultaneously analyze imaging and gait analysis techniques. PURPOSE: To identify biochemical and biomechanical biomarkers able to classify different disease progression phenotypes in subjects with and without radiographic signs of hip OA. STUDY TYPE: Longitudinal study for comparison of progressive and nonprogressive subjects. POPULATION: In all, 102 subjects with and without radiographic signs of hip osteoarthritis. FIELD STRENGTH/SEQUENCE: 3T, SPGR 3D MAPSS T1ρ /T2 , intermediate-weighted fat-suppressed fast spin-echo (FSE). ASSESSMENT: Multidimensional data analysis including cartilage composition, bone shape, Kellgren-Lawrence (KL) classification of osteoarthritis, scoring hip osteoarthritis with MRI (SHOMRI), hip disability and osteoarthritis outcome score (HOOS). STATISTICAL TESTS: Analysis done using TDA, Kolmogorov-Smirnov (KS) testing, and Benjamini-Hochberg to rank P-value results to correct for multiple comparisons. RESULTS: Subjects in the later stages of the disease had an increased SHOMRI score (P < 0.0001), increased KL (P = 0.0012), and older age (P < 0.0001). Subjects in the healthier group showed intact cartilage and less pain. Subjects found between these two groups had a range of symptoms. Analysis of this subgroup identified knee biomechanics (P < 0.0001) as an initial marker of the disease that is noticeable before the morphological progression and degeneration. Further analysis of an OA subgroup with femoroacetabular impingement (FAI) showed anterior labral tears to be the most significant marker (P = 0.0017) between those FAI subjects with and without OA symptoms. DATA CONCLUSION: The data-driven analysis obtained with TDA proposes new phenotypes of these subjects that partially overlap with the radiographic-based classical disease status classification and also shows the potential for further examination of an early onset biomechanical intervention. LEVEL OF EVIDENCE: 2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018;48:1046-1058.
Assuntos
Marcha , Processamento de Imagem Assistida por Computador/métodos , Imageamento por Ressonância Magnética , Osteoartrite do Quadril/diagnóstico por imagem , Acetábulo/diagnóstico por imagem , Adulto , Algoritmos , Fenômenos Biomecânicos , Cartilagem Articular/diagnóstico por imagem , Estudos de Casos e Controles , Progressão da Doença , Feminino , Fêmur/diagnóstico por imagem , Articulação do Quadril/diagnóstico por imagem , Humanos , Cinética , Estudos Longitudinais , Masculino , Pessoa de Meia-Idade , Osteoartrite do Joelho/diagnóstico por imagem , FenótipoRESUMO
PURPOSE: Quantitative MRI (QMRI) of the hip with sequences such as T1ρ and T2 mapping has been utilized to detect early changes in cartilage matrix composition. However, QMRI has not been performed in the presence of intra-articular contrast. Thus the purpose of this study was to evaluate the feasibility and use of QMRI during MR-arthrography (MRA) in femoracetabular impingement (FAI) patients. MATERIALS AND METHODS: Using a 3 Tesla MR-scanner, 10 FAI patients underwent a unilateral MRA and standard MRI of the hip joint. Global and sub-regional T1ρ and T2 relaxation times of the acetabular and femoral articular cartilage were computed in the MRA and MRI assessments and agreement of these values were assessed using the Krippendorff's alpha (α) coefficient and linear regression (µ). T1ρ and T2 relaxation times between the MRA and MRI were compared using a repeated measures analysis of variance. RESULTS: Both global and sub-regional T1ρ and T2 relaxation times demonstrated strong agreement (α > 0.83; µ > 0.85) independent of intra-articular contrast. Also, global and sub-regional acetabular T1ρ (P = 0.72) and T2 (P = 0.94), as well as femoral T1ρ , relaxation times were similar between MRA and MRI (P = 0.73) yet femoral T2 relaxation times decreased when using intra-articular contrast (P = 0.04). CONCLUSION: This study demonstrated the feasibility of T1ρ and T2 mapping for use in hip MRA with FAI patients. The inclusion of QMRI in MRA provides a quantitative assessment of the effects of FAI on hip joint articular cartilage while allowing for detailed assessment of labral pathology with the use of intra-articular contrast. J. Magn. Reson. Imaging 2016;44:1539-1545.
Assuntos
Cartilagem Articular/diagnóstico por imagem , Cartilagem Articular/patologia , Impacto Femoroacetabular/diagnóstico por imagem , Impacto Femoroacetabular/patologia , Articulação do Quadril/diagnóstico por imagem , Articulação do Quadril/patologia , Imageamento por Ressonância Magnética/métodos , Adulto , Artrografia/métodos , Estudos de Viabilidade , Feminino , Humanos , Interpretação de Imagem Assistida por Computador/métodos , Masculino , Pessoa de Meia-Idade , Reprodutibilidade dos Testes , Sensibilidade e EspecificidadeRESUMO
This paper studies the modeling of lower extremity muscle forces and their correlation to neuromuscular fatigue. Two analytical fatigue models were combined with a musculoskeletal model to estimate the effects of hamstrings fatigue on lower extremity muscle forces during a side step cut. One of the fatigue models (Tang) used subject-specific knee flexor muscle fatigue and recovery data while the second model (Xia) used previously established fatigue and recovery parameters. Both fatigue models were able to predict hamstrings fatigue within 20% of the experimental data, with the semimembranosus and semitendinosus muscles demonstrating the largest (11%) and smallest (1%) differences, respectively. In addition, various hamstrings fatigue levels (10-90%) on lower extremity muscle force production were assessed using one of the analytical fatigue models. As hamstrings fatigue levels increased, the quadriceps muscle forces decreased by 21% (p < 0.01), while gastrocnemius muscle forces increased by 36% (p < 0.01). The results of this study validate the use of two analytical fatigue models in determining the effects of neuromuscular fatigue during a side step cut, and therefore, this model can be used to assess fatigue effects on risk of lower extremity injury during athletic maneuvers. Understanding the effects of fatigue on muscle force production may provide insight on muscle group compensations that may lead to altered lower extremity motion patterns as seen in noncontact anterior cruciate ligament (ACL) injuries.
Assuntos
Simulação por Computador , Perna (Membro)/fisiologia , Fadiga Muscular , Feminino , Humanos , Modelos Biológicos , Músculo Esquelético/fisiologia , Adulto JovemRESUMO
The aim of this study was to determine the effects of hamstrings fatigue on lower extremity joint coordination variability during a sidestep cutting maneuver. Twenty female recreational athletes performed five successful trials of a sidestep cutting task pre- and postfatigue. Each participant completed an isolated hamstrings fatigue protocol consisting of isokinetic maximum effort knee flexion and passive extension contractions. Vector coding was used to examine hip and knee joint couplings (consisting of various planar motions) during the impact and weight acceptance phases of the sidestep cut stance phase. Paired t tests were used to analyze differences of each phase as an effect of fatigue, where alpha was set a priori at .05. The hip rotation/knee rotation coupling exhibited a significant decrease in coordination variability as a function of fatigue in both the impact (P = .015) and weight acceptance phases (P = .043). Similarly, the hip adduction-abduction/knee rotation coupling exhibited a significant decrease in coordination variability in the weight acceptance phase (P = .038). Hamstrings fatigue significantly decreased coordination variability within specific lower extremity joint couplings that included knee rotation. Future studies should be conducted to determine if this decrease in coordination variability is related to lower extremity injury mechanisms.
Assuntos
Articulação do Quadril/fisiologia , Articulação do Joelho/fisiologia , Fadiga Muscular/fisiologia , Músculo Esquelético/fisiologia , Amplitude de Movimento Articular/fisiologia , Corrida/fisiologia , Adaptação Fisiológica/fisiologia , Adulto , Simulação por Computador , Feminino , Humanos , Modelos Biológicos , Contração Muscular/fisiologia , Equilíbrio Postural/fisiologiaRESUMO
Objectives: Chronic pain is a risk factor for worse outcomes following hip arthroscopy for femoroacetabular impingement syndrome (FAIS). Pain sensitization involves the central nervous system perceiving previously innocuous stimuli as noxious. Temporal summation can provide a surrogate measure of sensitization, and may be a clinical tool to identify patients at a higher risk for poor post-hip arthroscopy outcomes. Therefore, we aimed to 1) identify the prevalence of temporal summation in patients undergoing hip arthroscopy for FAIS, 2) determine if there a difference in postoperative improvement between individuals with and without preoperative temporal summation, and 3) examine preoperative predictors of poor postoperative recovery. Methods: 51 participants undergoing hip arthroscopy for FAIS underwent preoperative temporal summation testing. Three months postoperatively, 38 participants completed the 12-item International Hip Outcome Tool (iHOT-12) and reported their overall symptomatic improvement (0% to 100%, with 100% being normal). Participants were categorized on the presence ( Numeric Pain Rating Scale; NPRS 2) or absence ( NPRS < 2) of temporal summation. A Mann-Whitney U test was used to determine the difference in improvement between groups (temporal summation: temporal summation (TS), no temporal summation (NTS), and a linear regression was used to explore predictors of improvement. Results: 23 (45.1%) of 51 participants displayed preoperative temporal summation. In participants with postoperative data, those with temporal summation reported less improvement than those without (TS: 62.8% 29.7%; NTS: 82.7% 13.9%; p = 0.01; Cohen's d = -0.86). Temporal summation (Beta = -0.48; 95% CI -36.6, -8.7) and mental health disorder (Beta = -0.30; 95% CI -28.0, -0.48) predicted 28.1% of the variance in postoperative improvement (p = 0.002). Conclusion: The presence of preoperative temporal summation is common and related to worse postoperative recovery after hip arthroscopy for FAIS.
RESUMO
BACKGROUND: Hypermobile Ehlers Danlos Syndrome, a heritable connective tissue disorder, is associated with muscle dysfunction, joint subluxations and pain. The impact of hypermobile Ehlers Danlos Syndrome on musculoskeletal mechanics is understudied. Therefore, the aim of this study was to assess the effects of hypermobile Ehlers Danlos Syndrome on lower extremity gait mechanics and muscle strength. METHODS: Eleven people with hypermobile Ehlers Danlos Syndrome and 11 asymptomatic controls underwent a 3D gait analysis and isometric hip and knee muscle strength assessment. Joint subluxations were self-reported by the hypermobile Ehlers Danlos syndrome group. Independent t-tests and Mann Whitney U tests were used to analyze joint mechanics, muscle strength, and patient report outcomes (p < 0.05). FINDINGS: Both groups exhibited similar walking speeds as well as similar hip, knee, and ankle joint kinematics. The hypermobile Ehlers Danlos Syndrome group walked with a lower peak hip extensor moment (hypermobile Ehlers Danlos Syndrome: -0.52 ± 0.28 NmËkg-1, Control: -0.83 ± 0.26 NmËkg-1, p = 0.01) yet similar knee and ankle joint moments. The hypermobile Ehlers Danlos Syndrome group exhibited a 40% deficit in peak hip extensor strength (hypermobile Ehlers Danlos Syndrome:1.07 ± 0.53 NmËkg-1, Control: 1.77 ± 0.79 NmËkg-1, p = 0.04). Approximately 73%, 55% and 45% of the hypermobile Ehlers Danlos Syndrome cohort self-reported hip, knee/patella and ankle joint subluxations, respectively, at least once a week. INTERPRETATION: Patients with hypermobile Ehlers Danlos Syndrome ambulated with altered hip extensor moments and exhibit hip extensor weakness. Future work should investigate the underlying mechanisms of hip extensor weakness and corresponding effects on joint health in people with hypermobile Ehlers Danlos Syndrome.
Assuntos
Síndrome de Ehlers-Danlos , Luxações Articulares , Instabilidade Articular , Humanos , Marcha/fisiologia , Força Muscular/fisiologiaRESUMO
BACKGROUND: Anterior cruciate ligament (ACL) reconstructions are associated with long-term functional impairments. Improved understanding of dynamic knee joint stiffness and work may provide insights to help address these poor outcomes. Defining the relationship between knee stiffness, work and quadriceps muscle symmetry may reveal therapeutic targets. The purposes of this study were to investigate between-limb differences in knee stiffness and work during early phase landing 6-months after an ACL reconstruction. Additionally, we investigated relationships among symmetry of knee joint stiffness and work during early-phase landing and quadriceps muscle performance symmetry. METHODS: Twenty-nine participants (17 M, 20.0 ± 5.3 years) were tested 6-months after ACL reconstruction. Motion capture analysis was used to assess between-limb differences in knee stiffness and work during the first 60 ms of a double-limb landing. Quadriceps peak strength and rate of torque development (RTD) were assessed with isometric dynamometry. Paired t-tests and Pearson's product moment correlations were used to determine between-limb differences of knee mechanics and correlations of symmetry respectively. FINDINGS: Knee joint stiffness and work were significantly reduced (p < 0.01, p < 0.01) in the surgical limb (0.021 ± 0.01 Nm*(deg*kg*m)-1, -0.085 ± 0.06 J*(kg*m) -1) compared to the uninvolved limb (0.045 ± 0.01 Nm*(deg*kg*m)-1, -0.256 ± 0.10 J*(kg*m) -1). Greater knee stiffness (51 ± 22%) and work (35 ± 21%) symmetry were significantly associated with greater RTD symmetry (44.5 ± 19.4%) (r = 0.43, p = 0.02; r = 0.45, p = 0.01) but not peak torque symmetry (62.9 ± 16.1%) (r = 0.32, p = 0.10; r = 0.34, p = 0.10). INTERPRETATION: Dynamic stiffness and energy absorption are lower in the surgical knee during landing from a jump. Therapeutic interventions that target increasing quadriceps RTD may help optimize dynamic stability and energy absorption during landing.