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1.
JAMA ; 325(7): 646-657, 2021 02 16.
Artigo em Inglês | MEDLINE | ID: mdl-33591346

RESUMO

Importance: Thigh muscle weakness is associated with knee discomfort and osteoarthritis disease progression. Little is known about the efficacy of high-intensity strength training in patients with knee osteoarthritis or whether it may worsen knee symptoms. Objective: To determine whether high-intensity strength training reduces knee pain and knee joint compressive forces more than low-intensity strength training and more than attention control in patients with knee osteoarthritis. Design, Setting, and Participants: Assessor-blinded randomized clinical trial conducted at a university research center in North Carolina that included 377 community-dwelling adults (≥50 years) with body mass index (BMI) ranging from 20 to 45 and with knee pain and radiographic knee osteoarthritis. Enrollment occurred between July 2012 and February 2016, and follow-up was completed September 2017. Interventions: Participants were randomized to high-intensity strength training (n = 127), low-intensity strength training (n = 126), or attention control (n = 124). Main Outcomes and Measures: Primary outcomes at the 18-month follow-up were Western Ontario McMaster Universities Osteoarthritis Index (WOMAC) knee pain (0 best-20 worst; minimally clinically important difference [MCID, 2]) and knee joint compressive force, defined as the maximal tibiofemoral contact force exerted along the long axis of the tibia during walking (MCID, unknown). Results: Among 377 randomized participants (mean age, 65 years; 151 women [40%]), 320 (85%) completed the trial. Mean adjusted (sex, baseline BMI, baseline outcome values) WOMAC pain scores at the 18-month follow-up were not statistically significantly different between the high-intensity group and the control group (5.1 vs 4.9; adjusted difference, 0.2; 95% CI, -0.6 to 1.1; P = .61) or between the high-intensity and low-intensity groups (5.1 vs 4.4; adjusted difference, 0.7; 95% CI, -0.1 to 1.6; P = .08). Mean knee joint compressive forces were not statistically significantly different between the high-intensity group and the control group (2453 N vs 2512 N; adjusted difference, -58; 95% CI, -282 to 165 N; P = .61), or between the high-intensity and low-intensity groups (2453 N vs 2475 N; adjusted difference, -21; 95% CI, -235 to 193 N; P = .85). There were 87 nonserious adverse events (high-intensity, 53; low-intensity, 30; control, 4) and 13 serious adverse events unrelated to the study (high-intensity, 5; low-intensity, 3; control, 5). Conclusions and Relevance: Among patients with knee osteoarthritis, high-intensity strength training compared with low-intensity strength training or an attention control did not significantly reduce knee pain or knee joint compressive forces at 18 months. The findings do not support the use of high-intensity strength training over low-intensity strength training or an attention control in adults with knee osteoarthritis. Trial Registration: ClinicalTrials.gov Identifier: NCT01489462.


Assuntos
Articulação do Joelho/fisiologia , Osteoartrite do Joelho/terapia , Manejo da Dor/métodos , Treinamento de Resistência/métodos , Idoso , Índice de Massa Corporal , Força Compressiva , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Osteoartrite do Joelho/complicações , Osteoartrite do Joelho/fisiopatologia , Dor/etiologia , Dor/reabilitação , Medição da Dor , Método Simples-Cego
2.
Bone Joint J ; 103-B(2): 338-346, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33517724

RESUMO

AIMS: This study aimed to identify the tibial component and femoral component coronal angles (TCCAs and FCCAs), which concomitantly are associated with the best outcomes and survivorship in a cohort of fixed-bearing, cemented, medial unicompartmental knee arthroplasties (UKAs). We also investigated the potential two-way interactions between the TCCA and FCCA. METHODS: Prospectively collected registry data involving 264 UKAs from a single institution were analyzed. The TCCAs and FCCAs were measured on postoperative radiographs and absolute angles were analyzed. Clinical assessment at six months, two years, and ten years was undertaken using the Knee Society Knee score (KSKS) and Knee Society Function score (KSFS), the Oxford Knee Score (OKS), the 36-Item Short-Form Health Survey questionnaire (SF-36), and range of motion (ROM). Fulfilment of expectations and satisfaction was also recorded. Implant survivorship was reviewed at a mean follow-up of 14 years (12 to 16). Multivariate regression models included covariates, TCCA, FCCA, and two-way interactions between them. Partial residual graphs were generated to identify angles associated with the best outcomes. Kaplan-Meier analysis was used to compare implant survivorship between groups. RESULTS: Significant two-way interaction effects between TCCA and FCCA were identified. Adjusted for each other and their interaction, a TCCA of between 2° and 4° and a FCCA of between 0° and 2° were found to be associated with the greatest improvements in knee scores and the probability of fulfilling expectations and satisfaction at ten years. Patients in the optimal group whose TCCA and FCCA were between 2° and 4°, and 0° and 2°, respectively, had a significant survival benefit at 15 years compared with the non-optimal group (optimal: survival = 100% vs non-optimal: survival = 92%, 95% confidence interval (CI) 88% to 96%). CONCLUSION: Significant two-way interactions between the TCCA and FCCA demonstrate the importance of evaluating the alignment of the components concomitantly in future studies. By doing so, we found that patients who concomitantly had both a TCCA of between 2° and 4° and a FCCA of between 0° and 2° had the best patient-reported outcome measures at ten years and better survivorship at 15 years. Cite this article: Bone Joint J 2021;103-B(2):338-346.


Assuntos
Artroplastia do Joelho/métodos , Hemiartroplastia/métodos , Prótese do Joelho , Osteoartrite do Joelho/cirurgia , Idoso , Idoso de 80 Anos ou mais , Artroplastia do Joelho/instrumentação , Fenômenos Biomecânicos , Feminino , Fêmur/patologia , Fêmur/fisiologia , Fêmur/cirurgia , Seguimentos , Hemiartroplastia/instrumentação , Humanos , Articulação do Joelho/patologia , Articulação do Joelho/fisiologia , Articulação do Joelho/cirurgia , Masculino , Pessoa de Meia-Idade , Medidas de Resultados Relatados pelo Paciente , Desenho de Prótese , Falha de Prótese , Sistema de Registros , Tíbia/patologia , Tíbia/fisiologia , Tíbia/cirurgia , Resultado do Tratamento
3.
Medicine (Baltimore) ; 100(3): e24066, 2021 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-33546008

RESUMO

ABSTRACT: A recent study suggested that baseball pitchers with glenohumeral internal rotation deficit (GIRD) may tend to use trunk rotation as compensation to adjust ball placement, which may lead to subsequent counter movement at the knee of the leading leg.This study aims to investigate the kinematic characteristics of the counter movements between the femur and the tibia (knee torsion), from the landing of the leading leg until the follow-through phase, during throwing between pitchers with and without GIRD at the dominant arm.This is a case-control study. Twenty-one senior high school baseball pitchers were recruited in this study. The glenohumeral internal and external rotation, hip internal and external rotation of all participants were measured. Eight pitchers without GIRD and 13 pitchers with GIRD were enrolled into the control group and experiment group, respectively. The maximal angular movement between the femur and the tibia (knee torsion) of the leading leg was measured, using The Zebris 3D (Zebris Medizintechnik GmbH, Isny, Germany) motion analysis system, in the interval from the landing until the follow-through phase during pitching a fastball to the bottom-outside corner with their dominant arm.The results showed that the maximal knee torsion of the leading leg in the experimental group (13.67 ±â€Š0.9 degrees) was significantly greater than the control group (4.25 ±â€Š1.369 degrees) (P < .05).Pitchers with GIRD had greater counter movement in the knee joint than pitchers without GIRD.


Assuntos
Beisebol/fisiologia , Articulação do Joelho/fisiologia , Articulação do Ombro/fisiologia , Adolescente , Fenômenos Biomecânicos , Estudos de Casos e Controles , Humanos , Masculino , Adulto Jovem
4.
PLoS One ; 15(12): e0244361, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33370355

RESUMO

Field-based sports require athletes to run sub-maximally over significant distances, often while contending with dynamic perturbations to preferred coordination patterns. The ability to adapt movement to maintain performance under such perturbations appears to be trainable through exposure to task variability, which encourages movement variability. The aim of the present study was to investigate the extent to which various wearable resistance loading magnitudes alter coordination and induce movement variability during running. To investigate this, 14 participants (three female and 11 male) performed 10 sub-maximal velocity shuttle runs with either no weight, 1%, 3%, or 5% of body weight attached to the lower limbs. Sagittal plane lower limb joint kinematics from one complete stride cycle in each run were assessed using functional data analysis techniques, both across the participant group and within-individuals. At the group-level, decreases in ankle plantarflexion following toe-off were evident in the 3% and 5% conditions, while increased knee flexion occurred during weight acceptance in the 5% condition compared with unloaded running. At the individual-level, between-run joint angle profiles varied, with six participants exhibiting increased joint angle variability in one or more loading conditions compared with unloaded running. Loading of 5% decreased between-run ankle joint variability among two individuals, likely in accordance with the need to manage increased system load or the novelty of the task. In terms of joint coordination, the most considerable alterations to coordination occurred in the 5% loading condition at the hip-knee joint pair, however, only a minority of participants exhibited this tendency. Coaches should prescribe wearable resistance individually to perturb preferred coordination patterns and encourage movement variability without loading to the extent that movement options become limited.


Assuntos
Articulação do Joelho/fisiologia , Extremidade Inferior/fisiologia , Corrida/fisiologia , Adulto , Fenômenos Biomecânicos , Feminino , Humanos , Masculino , Dispositivos Eletrônicos Vestíveis , Suporte de Carga , Adulto Jovem
5.
PLoS One ; 15(10): e0240181, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33007014

RESUMO

OBJECTIVES: The purpose of this study was to compare the duration of high-intensity static stretching on flexibility and strength in the hamstrings. METHODS: Fourteen healthy males (20.8 ± 0.6 years, 170.7 ± 6.5 cm, 66.4 ± 9.9 kg) underwent high-intensity static stretching for three different durations (10, 15, and 20 seconds). The intensity of static stretching was set at the maximum point of discomfort. To examine the change in flexibility and strength, range of motion, peak passive torque, relative passive torque, muscle-tendon unit stiffness, peak torque of isokinetic knee flexion, and knee angle at peak torque of isokinetic knee flexion were measured. To evaluate a time course of pain, a numerical rating scale was described. RESULTS: Range of motion (P < 0.01), peak passive torque (P < 0.01), and knee angle at peak torque were increased at all interventions. Relative passive torque (P < 0.01) and muscle-tendon unit stiffness (P < 0.01) were decreased at all interventions. Peak torque decreased after 10 seconds of stretching (P < 0.05). Numerical rating scale during stretching was 8-9 levels in all interventions, the pain disappeared immediately after the post-measurements (median = 0). CONCLUSION: The results suggested that muscle-tendon unit stiffness decreased regardless of duration of high-intensity static stretching. However, peak torque of isokinetic knee flexion decreased after 10 seconds of high-intensity static stretching, though it was no change after for more than 15 seconds of stretching.


Assuntos
Músculos Isquiossurais/fisiologia , Exercícios de Alongamento Muscular , Feminino , Humanos , Articulação do Joelho/fisiologia , Masculino , Amplitude de Movimento Articular/fisiologia , Tendões/fisiologia , Torque
6.
PLoS One ; 15(10): e0238785, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33052931

RESUMO

A human cadaveric specimen-specific knee model with appropriate soft tissue constraints was developed to appropriately simulate the biomechanical environment in the human knee, in order to pre-clinically evaluate the biomechanical and tribological performance of soft tissue interventions. Four human cadaveric knees were studied in a natural knee simulator under force control conditions in the anterior posterior (AP) and tibial rotation (TR) axes, using virtual springs to replicate the function of soft tissues. The most appropriate spring constraints for each knee were determined by comparing the kinematic outputs in terms of AP displacement and TR angle of the human knee with all the soft tissues intact, to the same knee with all the soft tissues resected and replaced with virtual spring constraints (spring rate and free length/degree). The virtual spring conditions that showed the least difference in the AP displacement and TR angle outputs compared to the intact knee were considered to be the most appropriate spring conditions for each knee. The resulting AP displacement and TR angle profiles under the appropriate virtual spring conditions all showed similar shapes to the individual intact knee for each donor. This indicated that the application of the combination of virtual AP and TR springs with appropriate free lengths/degrees was successful in simulating the natural human knee soft tissue function. Each human knee joint had different kinematics as a result of variations in anatomy and soft tissue laxity. The most appropriate AP spring rate for the four human knees varied from 20 to 55 N/mm and the TR spring rate varied from 0.3 to 1.0 Nm/°. Consequently, the most appropriate spring condition for each knee was unique and required specific combinations of spring rate and free length/degree in each of the two axes.


Assuntos
Joelho/fisiologia , Modelos Biológicos , Idoso , Fenômenos Biomecânicos , Cadáver , Simulação por Computador , Tecido Conjuntivo/anatomia & histologia , Tecido Conjuntivo/fisiologia , Feminino , Humanos , Joelho/anatomia & histologia , Articulação do Joelho/anatomia & histologia , Articulação do Joelho/fisiologia , Masculino , Pessoa de Meia-Idade , Amplitude de Movimento Articular , Rotação , Tíbia/anatomia & histologia , Tíbia/fisiologia , Torque
7.
Artigo em Inglês | MEDLINE | ID: mdl-32933208

RESUMO

Backward jump-landing during sports performance will result in dynamic postural instability with a greater risk of injury, and most research studies have focused on forward landing. Differences in kinematic temporal characteristics between single-leg and double-leg backward jump-landing are seldom researched and understood. The purpose of this study was to compare and analyze lower extremity kinematic differences throughout the landing phases of forward and backward jumping using single-leg and double-leg landings (FS and BS, FD and BD). Kinematic data were collected during the landing phases of FS and BS, FD and BD in 45 participants. Through statistical parametric mapping (SPM) analysis, we found that the BS showed smaller hip and knee flexion and greater vertical ground reactive force (VGRF) than the FS during 0-37.42% (p = 0.031), 16.07-32.11% (p = 0.045), and 23.03-17.32% (p = 0.041) landing phases. The BD showed smaller hip and knee flexion than the FD during 0-20.66% (p = 0.047) and 0-100% (p < 0.001) landing phases. Most differences appeared within a time frame during the landing phase at 30-50 ms in which non-contact anterior cruciate ligament (ACL) injuries are thought to occur and are consistent with the identification of risk in biomechanical analysis. A landing strategy that consciously increases the knee and hip flexion angles during backward landing should be considered for people as a measure to avoid injury during the performance of this type of physical activity.


Assuntos
Lesões do Ligamento Cruzado Anterior , Desempenho Atlético/fisiologia , Traumatismos do Joelho/prevenção & controle , Perna (Membro)/fisiologia , Extremidade Inferior/fisiologia , Movimento/fisiologia , Equilíbrio Postural/fisiologia , Adulto , Atletas , Fenômenos Biomecânicos/fisiologia , Humanos , Articulação do Joelho/fisiologia
8.
PLoS One ; 15(9): e0238722, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32911488

RESUMO

BACKGROUND: Osteoarthritis (OA) is a common problem in the older population. To reduce pain and stress in the affected knee joint compartment, a functional knee brace is often prescribed by physicians to protect it from high loads. OBJECTIVES: An instrumented gait analysis should evaluate how the 4-point knee orthosis for varus or valgus load relief (M.4s OA) changes the kinematics of the knee, especially in the frontal plane. METHODS: 17 healthy participants took part and were analyzed with an inertial sensor system (MyoMotion) giving continuous, objective information on the anatomical angles. The measurements were made both without wearing a knee brace and with the brace in different settings. RESULTS: The results show a significant reduction in the maximum knee abduction and raised knee adduction. The knee brace, with a strong adjustment in varus or valgus orientation, caused a shift of maximum ab-/adduction in the proposed direction in 69% and 75% of the dynamic tests, respectively. The knee motion in the frontal plane shows individual movement patterns. CONCLUSION: The use of the brace leads to significant changes in the knee's movement. Patient-specific movement patterns may explain different effects of functional knee braces on individual persons. Inertial sensors have been shown to be a low-cost, easy-to-use option for individual movement analysis and further personalized therapy.


Assuntos
Braquetes , Análise da Marcha , Articulação do Joelho/fisiologia , Movimento (Física) , Adulto , Fenômenos Biomecânicos , Feminino , Marcha/fisiologia , Humanos , Masculino , Movimento
9.
Geriatr Gerontol Int ; 20(10): 899-903, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32886828

RESUMO

AIM: Exercise therapy is a key intervention in the management of knee osteoarthritis (OA). This study aimed to test the 6-month effectiveness of Wu Qin Xi Qigong (WQXQ) exercise versus a conventional physical therapy (control group [CG]) on physical functioning in patients with early knee OA. METHODS: This study was a 6-month follow-up from a randomized controlled trial. Participants with knee OA were randomly allocated to the WQXQ or CG. Data from the Berg Balance Scale, Timed Up and Go Test, 6-Minute Walk Test, 30-Second Chair Stand Test, the Western Ontario and McMaster Universities Osteoarthritis Index, knee extension strength and knee flexion strength were collected before and after the 6-month intervention. RESULTS: Both treatment groups demonstrated large (20%-50%) and clinically relevant reductions in activity limitations, pain and knee instability, which were sustained at 6 months post-treatment. No differences in effectiveness between experimental and control treatment were found on Timed Up and Go Test, 6-Minute Walk Test, knee extension strength and knee flexion strength except for a higher Berg Balance Scale score (P = 0.029) and lower Western Ontario and McMaster Universities Osteoarthritis Index pain score (P = 0.031) in the WQXQ group. CONCLUSIONS: Both WQXQ and conventional physical therapy exercise programs were highly effective in reducing activity limitations and pain, and promoting balance and muscle power. WQXQ was found to be more effective in promoting balance and reducing pain than conventional physical therapy exercise in patients with knee OA. Geriatr Gerontol Int 2020; 20: 899-903.


Assuntos
Osteoartrite do Joelho/terapia , Modalidades de Fisioterapia , Qigong/métodos , Idoso , Idoso de 80 Anos ou mais , Estudos de Casos e Controles , China , Terapia por Exercício , Feminino , Humanos , Articulação do Joelho/fisiologia , Masculino , Pessoa de Meia-Idade , Força Muscular/fisiologia , Dor/reabilitação , Manejo da Dor/métodos , Medição da Dor , Equilíbrio Postural/fisiologia , Estudos de Tempo e Movimento , Resultado do Tratamento
10.
PLoS One ; 15(9): e0239148, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32936793

RESUMO

Lower limb exoskeletons and lower limb prostheses have the potential to reduce gait limitations during stair ambulation. To develop robotic assistance devices, the biomechanics of stair ambulation and the required transitions to level walking have to be understood. This study aimed to identify the timing of these transitions, to determine if transition phases exist and how long they last, and to investigate if there exists a joint-related order and timing for the start and end of the transitions. Therefore, this study analyzed the kinematics and kinetics of both transitions between level walking and stair ascent, and between level walking and stair descent (12 subjects, 25.4 yrs, 74.6 kg). We found that transitions primarily start within the stance phase and end within the swing phase. Transition phases exist for each limb, all joints (hip, knee, ankle), and types of transitions. They have a mean duration of half of one stride and they do not last longer than one stride. The duration of the transition phase for all joints of a single limb in aggregate is less than 35% of one stride in all but one case. The distal joints initialize stair ascent, while the proximal joints primarily initialize the stair descent transitions. In general, the distal joints complete the transitions first. We believe that energy- and balance-related processes are responsible for the joint-specific transition timing. Regarding the existence of a transition phase for all joints and transitions, we believe that lower limb exoskeleton or prosthetic control concepts should account for these transitions in order to improve the smoothness of the transition and to thus increase the user comfort, safety, and user experience. Our gait data and the identified transition timings can provide a reference for the design and the performance of stair ambulation- related control concepts.


Assuntos
Articulação do Tornozelo/fisiologia , Marcha/fisiologia , Articulação do Quadril/fisiologia , Articulação do Joelho/fisiologia , Subida de Escada/fisiologia , Adulto , Membros Artificiais , Fenômenos Biomecânicos/fisiologia , Exoesqueleto Energizado , Humanos , Extremidade Inferior , Masculino , Equilíbrio Postural/fisiologia , Desenho de Prótese/métodos , Amplitude de Movimento Articular/fisiologia , Fatores de Tempo , Adulto Jovem
11.
J Sports Sci ; 38(19): 2200-2207, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32921248

RESUMO

The aims of this study were (a) to describe the kinematics underlying the phenomenon of the knee of the swing leg passing medially in front of the athlete during the single push (SP) phase of the block sprint start, and (b) to determine the relationships between block phase pelvis range of motion (RoM), 1st step width and block phase performance. Three-dimensional kinematic data (250 Hz) were collected from eleven competitive sprinters (100 m PB: 11.17 ± 0.41) performing maximal effort block starts. The joint angles of the rear hip with respect to the pelvis and the pelvis segment angles with respect to the laboratory coordinate system were calculated during the block start phase to the end of the 1st stance. A combination of pelvis list and rotation (not hip adduction) was coupled with the thigh of the swing leg moving medially during the SP phase. A very high positive correlation was found between pelvic list RoM and 1st step width (r = 0.799, p = 0.003). No other significant correlations were found. Attempting to reduce pelvic RoM or changing frontal and transverse plane hip joint angles to minimise medial thigh motion is unlikely to lead to an improvement to performance.


Assuntos
Articulação do Joelho/fisiologia , Pelve/fisiologia , Corrida/fisiologia , Aceleração , Fenômenos Biomecânicos , Feminino , Análise da Marcha , Articulação do Quadril/fisiologia , Humanos , Masculino , Postura/fisiologia , Amplitude de Movimento Articular , Coxa da Perna/fisiologia , Estudos de Tempo e Movimento , Adulto Jovem
12.
PLoS One ; 15(8): e0237331, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32822398

RESUMO

Speed skating is a technical endurance sport. Still, little is known about technical changes in junior speed skaters. Therefore, changes in technique throughout a 1500-m time-trial of elite junior speed skaters is investigated to explore differences between sexes, performance levels and competitive seasons. At (inter)national 1500-m competitions, knee and push-off angles were obtained for 120 elite junior speed skaters (56 female, 64 male, age 17.6±1.1 years) per lap at 250m (lap 1), 650m (lap 2), 1050m (lap 3) and 1450m (lap 4). Additionally, 1500m end-times and lap-times were obtained to divide skaters in faster and slower performance groups and to analyze pacing behavior. Fifteen skaters (8 female, 7 male, age 17.3±1.5 years) were measured again after 1.6±0.6 years. (Repeated measures) ANOVAs were used for statistical analyses (p<0.05). ICC, determined in a pilot study, was 0.55 for knee and 0.76 for push-off angles. Elite junior speed skaters increased their knee angles throughout the race (p<0.005), regardless of sex (p = 0.110) or performance level (p = 0.714). Push-off angles increased from lap 1-3 (p<0.001), in which men showed a larger decay than female skaters (p<0.05), this holds for both performance groups (p = 0.103). Faster skaters had smaller knee and push-off angles than slower skaters (p<0.05). Males showed smaller body angles than females (p<0.001). Faster male and female skaters showed a relative slower start and faster lap 3 compared to slower skaters (p<0.05). Development over competitive seasons showed a shift towards smaller push-off angles (p = 0.038) and less decay in knee angles from lap 2-3 (p = 0.026). The present study shows that technique throughout the 1500m deteriorates. Deterioration in technique is regardless of performance level, even with different pacing behaviors. Differences between sexes were found for push-off angles. The longitudinal development suggests changes in technique towards senior level and highlights the importance of studying juniors separate from seniors.


Assuntos
Atletas/estatística & dados numéricos , Desempenho Atlético/fisiologia , Locomoção/fisiologia , Patinação/fisiologia , Adolescente , Fatores Etários , Desempenho Atlético/estatística & dados numéricos , Desempenho Atlético/tendências , Feminino , Humanos , Articulação do Joelho/fisiologia , Masculino , Países Baixos , Projetos Piloto , Fatores Sexuais , Patinação/estatística & dados numéricos , Patinação/tendências , Fatores de Tempo
13.
Artigo em Inglês | MEDLINE | ID: mdl-32824529

RESUMO

The impact of ultramarathons (UM) on the organs, especially in professional athletes, is poorly understood. We tested a 36-year-old UM male runner before and after winning a 24-h marathon. The primary goal of the study was cardiovascular assessment. The athlete experienced right knee pain for the first time after 12 h of running (approximately 130 km), which intensified, affecting his performance. The competitors ran on a 1984 m rectangle-loop (950 × 42 m) in an atypical clockwise fashion. The winner completed 516 rectangular corners. Right knee Magnetic Resonance Imaging (MRI) one day after the run showed general overload in addition to degenerative as well as specific features associated with "turning to the right". Re-examination after three years revealed none of these findings. Different kinds of overloading of the right lower limb, including right knee pain, were indicated in 6 of 10 competitors from the top 20, including a woman who set the world record. The affected competitors suggested as cause for discomfort the shape of the loop and running direction. They believed that changing the direction of the run during the competition and an athletics stadium loop shape on a 2000-2500 m length is better for 24-h UM runners. In the absence of technical alternatives, the "necessary evil" is a counterclockwise run (also Association of Athletics Federations IAAF recommendation). Results suggest that a one-way, clockwise, 24-h UM run had an adverse effect on the athlete's right knee, as a result of unsymmetrical load. Organizers of 24-h UM runs should consider the shape of the competition loop and apply the principle of uniform load on the musculoskeletal system (alternate directions run). In case of technical impossibility, it would be better to run counterclockwise, which is more common, preferred by runners, and recommended by the IAAF.


Assuntos
Articulação do Joelho , Corrida , Adulto , Atletas , Feminino , Humanos , Articulação do Joelho/diagnóstico por imagem , Articulação do Joelho/fisiologia , Extremidade Inferior , Imagem por Ressonância Magnética , Masculino
14.
PLoS One ; 15(8): e0237768, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32813742

RESUMO

INTRODUCTION: In cycling, the utilization of the drops position (i.e. the lowest handlebar position relative to the ground) allows for reduced frontal area, likely improved aerodynamics and thus performance compared to the tops (i.e. the position producing the most upright trunk). The reduced trunk angle during seated submaximal cycling has been shown to influence cardiorespiratory factors but the effects on pedalling forces and joint specific power are unclear. The purpose of this study was to investigate the effect of changing handgrip position on joint specific power and cycling kinematics at different external work rates in recreational and professional cyclists. METHOD: Nine professional and nine recreational cyclists performed cycling bouts using three different handgrip positions and three external work rates (i.e. 100W, 200W and external work rate corresponding to the lactate threshold (WRlt)). Joint specific power was calculated from kinematic measurements and pedal forces using 2D inverse dynamics. RESULTS: We found increased hip joint power, decreased knee joint power and increased peak crank torque for the professional cyclist compared to the recreational cyclists, but only at WRlt where the professional cyclists were working at a higher external work rate. There was no main effect of changing handgrip position on any joint, but there was a small interaction effect of external work rate and handgrip position on hip joint power contribution (Generalized eta squared (ηg2) = 0.012). At 100W, changing handgrip position from the tops to the drops decreased the hip joint contribution (-2.0 ± 3.9 percentage points (pct)) and at the WRlt, changing handgrip position increased the hip joint power (1.6 ± 3.1 pct). There was a small effect of handgrip position with the drops leading to increased peak crank torque (ηg2 = 0.02), increased mean dorsiflexion (ηg2 = 0.05) and increased hip flexion (ηg2 = 0.31) compared to the tops. DISCUSSION: The present study demonstrates that there is no main effect of changing handgrip position on joint power. Although there seems to be a small effect on hip joint power when comparing across large ranges in external work rate, any potential negative performance effect would be outweighed by the aerodynamic benefit of the drops position.


Assuntos
Atletas , Desempenho Atlético/fisiologia , Ciclismo/fisiologia , Postura/fisiologia , Articulação do Tornozelo/fisiologia , Fenômenos Biomecânicos , Mãos/fisiologia , Articulação do Quadril/fisiologia , Humanos , Articulação do Joelho/fisiologia , Masculino , Torque , Adulto Jovem
15.
J Vis Exp ; (161)2020 07 17.
Artigo em Inglês | MEDLINE | ID: mdl-32744530

RESUMO

Running is beneficial for physical health, but it is also accompanied by many injuries. However, the main factors leading to running injury remain unexplained. This study investigated the effects of long running distance on lower-limb kinematic variables and the lower limb kinematic difference of between the initial (IR) and terminal phase (TR) of 5 km running was compared. Ten amateur runners ran on a treadmill at the speed of 10 km/h. Dynamic kinematic data was collected at the phase of IR (0.5 km) and TR (5 km), respectively. The peak angle, peak angular velocities, and range of motion were recorded in this experiment. The main results demonstrated the following: ankle eversion and knee abduction were increased at TR; ROMs of ankle and knee were increased in the frontal plane at TR than IR; a larger peak angular velocity of ankle dorsiflexion and hip interrotation were found in TR compared to IR. These changes during the long distance running may provide some specific details for exploring potential reasons of running injuries.


Assuntos
Articulação do Tornozelo/fisiologia , Fenômenos Biomecânicos , Articulação do Joelho/fisiologia , Extremidade Inferior/fisiologia , Corrida , Adulto , Atletas , Teste de Esforço , Feminino , Humanos , Masculino , Movimento , Amplitude de Movimento Articular
16.
PLoS One ; 15(8): e0231996, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32857774

RESUMO

Lower-limb wearable robotic devices can improve clinical gait and reduce energetic demand in healthy populations. To help enable real-world use, we sought to examine how assistance should be applied in variable gait conditions and suggest an approach derived from knowledge of human locomotion mechanics to establish a 'roadmap' for wearable robot design. We characterized the changes in joint mechanics during walking and running across a range of incline/decline grades and then provide an analysis that informs the development of lower-limb exoskeletons capable of operating across a range of mechanical demands. We hypothesized that the distribution of limb-joint positive mechanical power would shift to the hip for incline walking and running and that the distribution of limb-joint negative mechanical power would shift to the knee for decline walking and running. Eight subjects (6M,2F) completed five walking (1.25 m s-1) trials at -8.53°, -5.71°, 0°, 5.71°, and 8.53° grade and five running (2.25 m s-1) trials at -5.71°, -2.86°, 0°, 2.86°, and 5.71° grade on a treadmill. We calculated time-varying joint moment and power output for the ankle, knee, and hip. For each gait, we examined how individual limb-joints contributed to total limb positive, negative and net power across grades. For both walking and running, changes in grade caused a redistribution of joint mechanical power generation and absorption. From level to incline walking, the ankle's contribution to limb positive power decreased from 44% on the level to 28% at 8.53° uphill grade (p < 0.0001) while the hip's contribution increased from 27% to 52% (p < 0.0001). In running, regardless of the surface gradient, the ankle was consistently the dominant source of lower-limb positive mechanical power (47-55%). In the context of our results, we outline three distinct use-modes that could be emphasized in future lower-limb exoskeleton designs 1) Energy injection: adding positive work into the gait cycle, 2) Energy extraction: removing negative work from the gait cycle, and 3) Energy transfer: extracting energy in one gait phase and then injecting it in another phase (i.e., regenerative braking).


Assuntos
Análise da Marcha/métodos , Marcha/fisiologia , Robótica/instrumentação , Adulto , Tornozelo/fisiologia , Articulação do Tornozelo/fisiologia , Fenômenos Biomecânicos , Exoesqueleto Energizado/tendências , Feminino , Quadril/fisiologia , Articulação do Quadril/fisiologia , Humanos , Joelho/fisiologia , Articulação do Joelho/fisiologia , Locomoção , Extremidade Inferior/fisiologia , Masculino , Músculo Esquelético/fisiologia , Corrida/fisiologia , Caminhada/fisiologia
17.
Clin Interv Aging ; 15: 1045-1056, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32636619

RESUMO

Aim: This study aimed to determine the association of handgrip strength with isometric and isokinetic strength (hip, knee and ankle extensor/flexor muscles), and functional capacity in older women. Methods: The handgrip strength and lower limb strength of 199 older women (60-86 years) were measured using JAMAR and BIODEX dynamometers, respectively. Time Up and Go, Five-times-sit-to-stand and 6m-walk functional tests were evaluated. Pearson correlations were used to determine the relationship between variables. Regression analysis was applied to identify if HS was able to predict TUG performance. The effect of age was analyzed by splitting the participants in a group of older women (OLD; from 60 to 70 years old) and very old women (from 71 to 86 years old). Results: The HS and isometric/isokinetic strength correlations were negligible/low and, in most cases, were non-significant. The correlation between handgrip strength and functional tests also ranged predominantly from negligible (r=0.0 to 0.3) to low (r=0.3 to 0.5), irrespective of the group age. The handgrip strength was not able to explain the variance of the TUG performance. Conclusion: Generalizing handgrip strength as a practical and straightforward measure to determine lower limbs and overall strength, and functional capacity in older women must be viewed with caution. Handgrip strength and standard strength measures of the lower limbs and functional tests present a negligible/low correlation.


Assuntos
Força da Mão/fisiologia , Perna (Membro)/fisiologia , Força Muscular/fisiologia , Músculo Esquelético/fisiologia , Desempenho Físico Funcional , Idoso , Idoso de 80 Anos ou mais , Feminino , Avaliação Geriátrica/métodos , Humanos , Articulação do Joelho/fisiologia , Caminhada/fisiologia
18.
Artigo em Inglês | MEDLINE | ID: mdl-32575511

RESUMO

The study investigated the influence of ankle strength and its range of motion (ROM) on knee kinematics during drop landing. Fifteen male and fifteen female university athletes with a normal range of dynamic knee valgus (DKV) (knee frontal plane projection angle: men = 3° to 8°, females = 7° to 13°) were recruited. They performed drop landing at height 30 cm and 45 cm with three-dimensional motion capture and analysis. Knee angles were compared at specific landing phases. Isokinetic ankle strength was tested at 60°/s angular velocity while the weight-bearing lunge test was conducted to evaluate ankle ROM. For males, strength for both plantarflexors and dorsiflexors were associated with knee kinematics at both heights (30 cm: r = -0.50, p = 0.03; 45 cm: r = -0.45, p = 0.05) during maximum vertical ground reaction force (MVGRF) phase. For females, ankle invertor strength and knee kinematics were associated at both 30cm (r = 0.53; p = 0.02,) and 45 cm landing heights (r = 0.49, p = 0.03), while plantarflexor strength and knee kinematics showed a significant association during initial contact (r = 0.70, p < 0.01) and MVGRF (r = 0.55, p = 0.02) phases at height 30 cm only. Male and female athletes with normal range of DKV showed a significant relationship between ankle strength and knee kinematics at specific landing phases. These relationships varied with increased landing height.


Assuntos
Articulação do Joelho , Amplitude de Movimento Articular , Articulação do Tornozelo , Atletas , Feminino , Humanos , Joelho , Articulação do Joelho/fisiologia , Masculino
19.
J Sports Med Phys Fitness ; 60(6): 848-854, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32487980

RESUMO

BACKGROUND: The aim of this study was to evaluate the effect of 12 weeks of use of orthopedic insoles equipped with a metatarsal retro-capital bar (MRCB) on plantar pressure under the feet and lower limb kinematic variables during running. METHODS: Two groups of 10 runners used for 12 weeks while running orthopedic insoles without correction or equipped with a MRCB. All participants performed successively a standing posture (CoP displacement) test and a running test at 11 km.h-1 (lower limb kinematic variables) using with flat insoles and orthopedic neutral or MRCB insoles at the beginning (T0), after 4 (T4) and 12 weeks (T12) of use. RESULTS: For the MRCB group, CoP moved backwards while forefoot plantar pressure was decreased during standing position at T4 and T12 compared to T0. During running, the plantar pressure under the 2nd, 3rd and 4th metatarsal heads was reduced with MRCB at T0, T4 and T12. The one under the 1st metatarsal head was decreased at T4 and T12, when MRCB or flat insoles were used. The maximal extension and the total amplitude of ankle were slightly increased at T4 and T12 with or without wearing MRCB insoles. Similar changes in knee joint kinematics were observed but only at T12. Any significant changes were found in runners that used orthopedic insoles without correction. CONCLUSIONS: Orthopedic insoles equipped with MRCB involve lower plantar pressure under the metatarsal heads, which may be of interest to treat forefoot injuries in runners.


Assuntos
Pé/fisiologia , Ossos do Metatarso/fisiologia , Corrida/fisiologia , Adulto , Articulação do Tornozelo/química , Articulação do Tornozelo/fisiologia , Fenômenos Biomecânicos , Feminino , Órtoses do Pé , Humanos , Articulação do Joelho/química , Articulação do Joelho/fisiologia , Masculino , Ossos do Metatarso/química , Pressão , Sapatos
20.
J Sports Sci ; 38(18): 2054-2062, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32475221

RESUMO

Cricket fast bowling is a dynamic activity in which a bowler runs up and repeatedly delivers the ball at high speeds. Experimental studies have previously linked ball release speed and several technique parameters with conflicting results. As a result, computer simulation models are increasingly being used to understand the effects of technique on performance. This study evaluates a planar 16-segment whole-body torque-driven simulation model of the front foot contact phase of fast bowling by comparing simulation output with the actual performance of an elite fast bowler. The model was customised to the bowler by determining subject-specific inertia and torque parameters. Good agreement was found between actual and simulated performances with a 4.0% RMS difference. Varying the activation timings of the torque generators resulted in an optimised simulation with a ball release speed 3.5 m/s faster than the evaluation simulation. The optimised technique used more extended front ankle and knee joint angles, increased trunk flexion and a longer delay in the onset of arm circumduction. These simulations suggest the model provides a realistic representation of the front foot contact phase of fast bowling and is suitable to investigate the limitations of kinematic or kinetic variables on fast bowling performance.


Assuntos
Simulação por Computador , Críquete/fisiologia , Pé/fisiologia , Destreza Motora/fisiologia , Adolescente , Articulação do Tornozelo/fisiologia , Braço/fisiologia , Fenômenos Biomecânicos , Humanos , Articulação do Joelho/fisiologia , Masculino , Tronco/fisiologia
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