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1.
J Biomech ; 166: 112062, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38555779

RESUMO

The purpose of this study was to determine the material stresses experienced in the femoral neck during the stepping phase of recovery from a forward loss of balance achieved both using release from a static forward lean and rapid treadmill accelerations in 8 older adults. A scalable musculoskeletal model with 23 degrees of freedom and 92 force actuators was used to calculate joint reaction forces. A finite element model of the femur used joint reaction forces calculated by the musculoskeletal model to calculate the material stresses during stepping. Balance recovery from a static forward lean angle had a greater joint contact force and greater maximum tensile stress than a recovery from treadmill induced perturbations both before and after a training session. Hip joint contact loads were found to be large in magnitude, however, all stresses experienced by the bone are less than critical yield stresses for trabecular bone. We suggest that stepping balance recovery is safe for older adults with no obvious loss of bone density or strength and that analyses such as finite element analysis are necessary to understand stresses in the material at the joint level.


Assuntos
Fêmur , Extremidade Inferior , Análise de Elementos Finitos , Articulação do Quadril , Colo do Fêmur , Estresse Mecânico
2.
J Strength Cond Res ; 37(10): 1947-1954, 2023 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-37556813

RESUMO

ABSTRACT: Goodman, WW, Helms, E, and Graham, DF. Individual muscle contributions to the acceleration of the center of mass during the barbell back squat in trained female subjects. J Strength Cond Res 37(10): 1947-1954, 2023-The squat is used to enhance performance and rehabilitate the lower body. However, muscle forces and how muscles accelerate the center of mass (CoM) are not well understood. The purpose was to determine how lower extremity muscles contribute to the vertical acceleration of the CoM when squatting to parallel using 85% one-repetition maximum. Thirteen female subjects performed squats in a randomized fashion. Musculoskeletal modeling was used to obtain muscle forces and muscle-induced accelerations. The vasti, soleus, and gluteus maximus generated the largest upward accelerations of the CoM, whereas the muscles that produced the largest downward acceleration about the CoM were the hamstrings, iliopsoas, adductors, and tibialis anterior. Our findings indicate that a muscle's function is task and posture specific. That is, muscle function depends on both joint position and how an individual is interacting with the environment.


Assuntos
Músculo Esquelético , Postura , Humanos , Feminino , Músculo Esquelético/fisiologia , Postura/fisiologia , Quadril/fisiologia , Aceleração , Nádegas , Fenômenos Biomecânicos
3.
Gait Posture ; 104: 151-158, 2023 07.
Artigo em Inglês | MEDLINE | ID: mdl-37421811

RESUMO

BACKGROUND: People with mild-to-moderate hip osteoarthritis (OA) exhibit hip muscle weakness, alterations in hip kinematics and kinetics and hip contact forces during gait compared to healthy controls. However, it is unclear if those with hip OA use different motor control strategies to coordinate the motion of the centre of mass (COM) during gait. Such information could provide further critical assessment of conservative management strategies implemented for people with hip OA. RESEARCH QUESTION: Do muscle contributions to the acceleration of the COM during walking differ between individuals with mild-to-moderate hip OA and controls? METHODS: Eleven individuals with mild-to-moderate hip OA and 10 healthy controls walked at a self-selected speed while whole-body motion and ground reaction forces were measured. Muscle forces during gait were obtained using static optimisation and an induced acceleration analysis was performed to determine individual muscle contributions to the acceleration of the COM during single-leg stance (SLS). Between-group comparisons were made using independent t-tests via Statistical Parametric Modelling. RESULTS: There were no between-group differences in spatial-temporal gait parameters or three-dimensional whole-body COM acceleration. The rectus femoris, biceps femoris, iliopsoas and gastrocnemius muscles in the hip OA group contributed less to the fore-aft accelerations of the COM (p < 0.05), and more to the vertical COM acceleration with the gluteus maximus (p < 0.05), during SLS, compared to the control group. SIGNIFICANCE: Subtle differences exist in the way people with mild-to-moderate hip OA use their muscles to accelerate the whole-body centre of mass during the SLS phase of walking relative to healthy controls. These findings improve understanding of the complex functional consequences of hip OA and enhance our understanding of how to monitor the effectiveness of an intervention on biomechanical changes in gait in people with hip OA.


Assuntos
Osteoartrite do Quadril , Humanos , Marcha/fisiologia , Caminhada/fisiologia , Músculo Esquelético/fisiologia , Fenômenos Biomecânicos , Aceleração , Debilidade Muscular
4.
J Appl Physiol (1985) ; 132(4): 956-965, 2022 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-35142563

RESUMO

A better understanding of the strains experienced by the Achilles tendon during commonly prescribed exercises and locomotor tasks is needed to improve efficacy of Achilles tendon training and rehabilitation programs. The aim of this study was to estimate in vivo free Achilles tendon strain during selected rehabilitation, locomotor, jumping, and landing tasks. Sixteen trained runners with no symptoms of Achilles tendinopathy participated in this study. Personalized free Achilles tendon moment arm and force-strain curve were obtained from imaging data and used in conjunction with motion capture and surface electromyography to estimate free Achilles tendon strain using electromyogram-informed neuromusculoskeletal modeling. There was a strong correspondence between Achilles tendon force estimates from the present study and experimental data reported in the literature (R2 > 0.85). The average tendon strain was highest for maximal hop landing (8.8 ± 1.6%), lowest for walking at 1.4 m/s (3.1 ± 0.8%), and increased with locomotor speed during running (run 3.0 m/s: 6.5 ± 1.6%; run 5.0 m/s: 7.9 ± 1.7%) and during heel rise exercise with added mass (BW: 5.8 ± 1.3%; 1.2 BW: 6.9 ± 1.7%). The peak tendon strain was highest during running (5 m/s: 13.7 ± 2.5%) and lowest during walking (1.4 m/s: 7 ± 1.8%). Overall findings provide a preliminary evidence base for exercise selection to maximize anabolic tendon remodeling during training and rehabilitation of the Achilles tendon.NEW & NOTEWORTHY Our work combines medical imaging and electromyogram-informed neuromusculoskeletal modeling data to estimate free Achilles tendon strain during selected rehabilitation, locomotor, jumping, and landing tasks in trained middle-distance runners. These data may potentially be used to inform Achilles tendon training and rehabilitation to maximize anabolic tendon remodeling.


Assuntos
Tendão do Calcâneo , Corrida , Tendinopatia , Traumatismos dos Tendões , Fenômenos Biomecânicos , Humanos , Caminhada
5.
Artigo em Inglês | MEDLINE | ID: mdl-32903393

RESUMO

Musculoskeletal tissues, including tendons, are sensitive to their mechanical environment, with both excessive and insufficient loading resulting in reduced tissue strength. Tendons appear to be particularly sensitive to mechanical strain magnitude, and there appears to be an optimal range of tendon strain that results in the greatest positive tendon adaptation. At present, there are no tools that allow localized tendon strain to be measured or estimated in training or a clinical environment. In this paper, we first review the current literature regarding Achilles tendon adaptation, providing an overview of the individual technologies that so far have been used in isolation to understand in vivo Achilles tendon mechanics, including 3D tendon imaging, motion capture, personalized neuromusculoskeletal rigid body models, and finite element models. We then describe how these technologies can be integrated in a novel framework to provide real-time feedback of localized Achilles tendon strain during dynamic motor tasks. In a proof of concept application, Achilles tendon localized strains were calculated in real-time for a single subject during walking, single leg hopping, and eccentric heel drop. Data was processed at 250 Hz and streamed on a smartphone for visualization. Achilles tendon peak localized strains ranged from ∼3 to ∼11% for walking, ∼5 to ∼15% during single leg hop, and ∼2 to ∼9% during single eccentric leg heel drop, overall showing large strain variation within the tendon. Our integrated framework connects, across size scales, knowledge from isolated tendons and whole-body biomechanics, and offers a new approach to Achilles tendon rehabilitation and training. A key feature is personalization of model components, such as tendon geometry, material properties, muscle geometry, muscle-tendon paths, moment arms, muscle activation, and movement patterns, all of which have the potential to affect tendon strain estimates. Model personalization is important because tendon strain can differ substantially between individuals performing the same exercise due to inter-individual differences in these model components.

6.
PLoS One ; 12(10): e0185564, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29069097

RESUMO

The purpose of this study was to determine the muscular contributions to the acceleration of the whole body centre of mass (COM) of older compared to younger adults that were able to recover from forward loss of balance with a single step. Forward loss of balance was achieved by releasing participants (14 older adults and 6 younger adults) from a static whole-body forward lean angle of approximately 18 degrees. 10 older adults and 6 younger adults were able to recover with a single step and included in subsequent analysis. A scalable anatomical model consisting of 36 degrees-of-freedom was used to compute kinematics and joint moments from motion capture and force plate data. Forces for 92 muscle actuators were computed using Static Optimisation and Induced Acceleration Analysis was used to compute individual muscle contributions to the three-dimensional acceleration of the whole body COM. There were no significant differences between older and younger adults in step length, step time, 3D COM accelerations or muscle contributions to 3D COM accelerations. The stance and stepping leg Gastrocnemius and Soleus muscles were primarily responsible for the vertical acceleration experienced by the COM. The Gastrocnemius and Soleus from the stance side leg together with bilateral Hamstrings accelerated the COM forwards throughout balance recovery while the Vasti and Soleus of the stepping side leg provided the majority of braking accelerations following foot contact. The Hip Abductor muscles provided the greatest contribution to medial-lateral accelerations of the COM. Deficits in the neuromuscular control of the Gastrocnemius, Soleus, Vasti and Hip Abductors in particular could adversely influence balance recovery and may be important targets in interventions to improve balance recovery performance.


Assuntos
Músculo Esquelético/fisiologia , Equilíbrio Postural , Adulto , Idoso , Idoso de 80 Anos ou mais , Humanos
7.
J Biomech ; 49(13): 2619-2624, 2016 09 06.
Artigo em Inglês | MEDLINE | ID: mdl-27288331

RESUMO

Hip joint contact loads during activities of daily living are not generally considered high enough to cause acute bone or joint injury. However there is some evidence that hip joint loads may be higher in stumble recovery from loss of balance. A common laboratory method used to evaluate balance recovery performance involves suddenly releasing participants from various static forward lean magnitudes (perturbation intensities). Prior studies have shown that when released from the same perturbation intensity, some older adults are able to recover with a single step, whereas others require multiple steps. The main purpose of this study was to use a musculoskeletal model to determine the effect of three balance perturbation intensities and the use of single versus multiple recovery steps on hip joint contact loads during recovery from forward loss of balance in community dwelling older adults (n=76). We also evaluated the association of peak hip contact loads with perturbation intensity, step length and trunk flexion angle at foot contact at each participant׳s maximum recoverable lean angle (MRLA). Peak hip joint contact loads were computed using muscle force estimates obtained using Static Optimisation and increased as lean magnitude was increased and were on average 32% higher for Single Steppers compared to Multiple Steppers. At the MRLA, peak hip contact loads ranged from 4.3 to 12.7 body weights and multiple linear stepwise regression further revealed that initial lean angle, step length and trunk angle at foot contact together explained 27% of the total variance in hip joint contact load. Overall findings indicated that older adults experience peak hip joint contact loads during maximal balance recovery by stepping that in some cases exceeded loads reported to cause mechanical failure of cadaver femurs. While step length and trunk flexion angle are strong predictors of step recovery performance they are at best moderate predictors of peak hip joint loading.


Assuntos
Acidentes por Quedas/prevenção & controle , Articulação do Quadril/fisiologia , Equilíbrio Postural , Atividades Cotidianas , Adulto , Idoso , Fenômenos Biomecânicos , Feminino , Marcha , Humanos , Masculino , Modelos Anatômicos , Estudos Prospectivos , Amplitude de Movimento Articular
8.
Exp Gerontol ; 66: 39-46, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-25871728

RESUMO

Falls are prevalent in older adults and are predicted by the maximum forward lean magnitude (MRLM) that can be recovered using a single step. The purpose of this study was to determine the relative contribution of selected neuromuscular and biomechanical variables associated with balance recovery to the MRLM. Forward loss of balance was induced by releasing participants (n=117 community-dwelling older adults) from a static forward lean angle. Participants were instructed to attempt to recover balance by taking a single step. A scalable anatomical model consisting of 36 degrees-of-freedom was used to compute kinematics and joint moments from motion capture and force plate data. Isometric muscle strength at the ankle, knee and hip joints was assessed using a dynamometer. A univariate analysis revealed that lower limb strength measures, step recovery kinematics, and stepping limb kinetics accounted for between 8 and 19%, 3 and 59%, and 3 and 61% of the variance in MRLM respectively. When all variables were entered into a stepwise multiple regression analysis, normalised step length, peak hip extension moment, trunk angle at foot contact, and peak hip flexion power during stepping together accounted for 69% of the variance in MRLM. These findings confirm that successful recovery from forward loss of balance is a whole body control task that requires adequate trunk control and generation of adequate lower limb moments and powers to generate a long and rapid step. Training programmes that specifically target these measures may be effective in improving balance recovery performance and thereby contribute to fall prevention amongst older adults.


Assuntos
Acidentes por Quedas/prevenção & controle , Envelhecimento/fisiologia , Força Muscular/fisiologia , Equilíbrio Postural/fisiologia , Amplitude de Movimento Articular/fisiologia , Idoso , Articulação do Tornozelo/fisiologia , Fenômenos Biomecânicos , Feminino , Pé/fisiologia , Humanos , Articulação do Joelho/fisiologia , Extremidade Inferior/fisiologia , Masculino , Prognóstico , Análise de Regressão
9.
J Sci Med Sport ; 17(1): 134-8, 2014 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-23601797

RESUMO

OBJECTIVES: To determine the effect size of wearing sports garments treated with microscopic titanium particles (AQUA TITAN) during recovery from strenuous running on the restoration of running economy during subsequent exercise. DESIGN: A double-blind crossover was used to determine the effect of AQUA TITAN on running metabolic cost in 10 healthy men. Participants performed 40 min of treadmill running comprising 2×(10 min at 5% and 10 min at -10% grade), followed by random allocation to skin-tight nylon-polyurethane AQUA TITAN treated or non-treated placebo garments covering the torso, limbs, and feet. Garments were worn continuously throughout the next 48-h, during which time participants rested (day 2) then completed a graded treadmill run to determine metabolic outcome (day 3). METHODS: Body-weight normalised running metabolic cost was evaluated by indirect calorimetry and the effect size referenced against the smallest meaningful change in economy (0.9%) for improvement in distance running performance. RESULTS: The fatigue effect while wearing control garments on metabolic cost at 48-h was small (2.2% 95%CL ±1.2%). In contrast, AQUA TITAN garments most certainly reduced running metabolic cost (-3.1% ±0.9%) vs. control. Additionally, AQUA TITAN increased the respiratory exchange ratio (0.011 ±0.005) and lowered minute ventilation at intensities below the ventilatory threshold (-4.0% ±0.9%). CONCLUSIONS: AQUA TITAN garments worn during recovery from strenuous exercise improved subsequent running economy to a magnitude likely to restore endurance performance. Future research should verify the magnitude of garment effects on performance outcomes, and on identifying the acute or passive neural, musculotendinous or metabolic mechanisms responsible.


Assuntos
Vestuário , Metabolismo Energético/efeitos dos fármacos , Exercício Físico , Corrida , Titânio/administração & dosagem , Adulto , Estudos Cross-Over , Método Duplo-Cego , Voluntários Saudáveis , Humanos , Masculino , Adulto Jovem
10.
J Biomech ; 47(3): 667-74, 2014 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-24360199

RESUMO

The purpose of this study was to determine the muscular contributions to the stepping phase of recovery from forward loss of balance in 5 young and 5 older adults that were able to recover balance in a single step, and 5 older adults that required multiple steps. Forward loss of balance was achieved by releasing participants from a static forward lean angle. All participants were instructed to attempt to recover balance by taking a rapid single step. A scalable anatomical model consisting of 36 degrees-of-freedom was used to compute kinematics and joint moments from motion capture and force plate data. Forces for 94 muscle actuators were computed using static optimisation and induced acceleration analysis was used to compute individual muscle contributions to net lumbar spine joint, and stepping side hip joint and knee joint accelerations during recovery. Older adults that required multiple recovery steps used a significantly shorter and faster initial recovery step and adopted significantly more trunk flexion throughout recovery compared to the older single steppers. Older multiple steppers also produced significantly more force in the stance side hamstrings, which resulted in significantly higher hamstring induced flexion accelerations at the lumbar spine and extension accelerations at the hip. However since the net joint lumbar spine and hip accelerations remained similar between older multiple steppers and older single steppers, we suggest that the recovery strategy adopted by older multiple steppers was less efficient as well as less effective than for older single steppers.


Assuntos
Envelhecimento/fisiologia , Marcha/fisiologia , Modelos Biológicos , Músculo Esquelético/fisiologia , Equilíbrio Postural/fisiologia , Aceleração , Acidentes por Quedas/prevenção & controle , Adulto , Idoso , Fenômenos Biomecânicos/fisiologia , Articulação do Quadril/fisiologia , Humanos , Articulação do Joelho/fisiologia , Vértebras Lombares/fisiologia , Masculino , Amplitude de Movimento Articular/fisiologia
11.
Springerplus ; 2: 653, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-24349956

RESUMO

We previously reported increased running economy and joint range of motion (ROM) during subsequent exercise performed 48-h following strenuous exercise while wearing garments containing micro-titanium particles generated from high-pressure aqueous processing of titanium (AQUA TITAN(TM)). Here we utilised an isolated plantarflexion triceps surae model and AQUA TITAN-treated flexible tape to determine if dermal application of the micro-titanium could account for meaningful changes in functional properties of the musculotendinous unit. In a randomised double-blind crossover, 20 trained men day 1, baseline measures, AQUA TITAN or placebo tape covering the triceps surae, intermittent high-intensity treadmill running; day 2, rest; day 3, post-stress post-treatment outcome measures. Outcomes comprised: plantarflexion ROM via isokinetic dynamometry; short latency reflex from electromyography; Achilles tendon stiffness from isometric dynamometry, ultrasonography (Achilles-medial-gastrocnemius junction), motion analysis, and force-length modelling. High-intensity exercise with placebo tape reduced tendon stiffness (-16.5%; 95% confidence limits ±8.1%; small effect size), relative to non-taped baseline, but this effect was negligible (-5.9%; ±9.2%) with AQUA TITAN (AQUA TITAN-placebo difference -11.3%; ±11.6%). Change in latency relative to baseline was trivial with placebo (1.6%; ±3.8%) but large with AQUA TITAN (-11.3%; ±3.3%). The effects on ROM with AQUA TITAN (1.6%; ±2.0%) and placebo were trivial (-1.6% ±1.9%), but the small difference (3.1%; ±2.7%) possibly greater with AQUA TITAN. AQUA TITAN tape accelerated the reflex response and attenuated reduced Achilles tendon stiffness following fatiguing exercise. Altered neuromuscular control of tendon stiffness via dermal application of micro-titanium treated materials may facilitate restoration of musculotendinous contractile performance following prior strenuous exercise.

12.
Appl Physiol Nutr Metab ; 33(1): 39-51, 2008 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-18347652

RESUMO

Nutrition is an important aspect of recuperation for athletes during multi-day competition or hard training. Post-exercise carbohydrate is likely to improve recovery, but the effect of protein is equivocal. The objective of this study was to determine the effect of post-exercise dietary protein content imposed over a high-carbohydrate background on subsequent performance. Using a crossover design, 12 cyclists completed 3 high-intensity rides over 4 days. Day 1 comprised 2.5 h intervals, followed by repeat-sprint performance tests on days 2 (15 h post) and 4 (60 h post), interspersed with a rest day. During 4 h recovery on days 1 and 2, cyclists ingested either 1.4 g.kg(-1).h(-1) carbohydrate, 0.7 g.kg(-1).h(-1) protein and 0.26 g.kg(-1).h(-1) fat (protein-enriched) or 2.1 g.kg(-1).h(-1) carbohydrate, 0.1 g.kg(-1).h(-1) protein, and equal fat (control). At other times, cyclists ingested a standardized high-carbohydrate diet. Anabolism was gauged indirectly by nitrogen balance, stress and inflammation via cortisol and cytokines, skeletal-muscle membrane disruption by creatine kinase, and oxidative stress by malonyl dealdehyde. Sprint mean power was not clearly different on day 2 (0.0%; 95%CL: +/-3.9%), but on day 4 it was 4.1% higher (+/-4.1%) in the protein-enriched condition relative to control. Reduced creatine kinase was possible (26%; +/-30%) but effects on oxidative stress, inflammatory markers, and cortisol were inconclusive or trivial. Overnight nitrogen balance was positive in the protein-enriched condition on day 1 (249+/-70 mg N.kg FFM(-1); mean+/-SD), but negative (-48+/-26 mg N.kg FFM(-1)) in the control condition. A nutritive effect of post-exercise protein content was not discernible short term (15 h), but a delayed performance benefit (60 h) was observed following protein-enriched high-carbohydrate ingestion.


Assuntos
Proteínas Alimentares/administração & dosagem , Exercício Físico/fisiologia , Músculo Esquelético/fisiologia , Miosite/dietoterapia , Estresse Oxidativo/fisiologia , Estresse Fisiológico/dietoterapia , Adulto , Glicemia , Proteína C-Reativa/metabolismo , Membrana Celular/metabolismo , Membrana Celular/patologia , Método Duplo-Cego , Fadiga/dietoterapia , Fadiga/imunologia , Fadiga/patologia , Humanos , Hidrocortisona/sangue , Interleucina-6/sangue , Ácido Láctico/sangue , Masculino , Músculo Esquelético/imunologia , Músculo Esquelético/patologia , Miosite/imunologia , Miosite/patologia , Nitrogênio/sangue , Recuperação de Função Fisiológica/fisiologia , Fator de Necrose Tumoral alfa/sangue
13.
Int J Sport Nutr Exerc Metab ; 17(6): 521-43, 2007 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-18156659

RESUMO

Carbohydrate ingestion after prolonged strenuous exercise enhances recovery, but protein might also be important. In a crossover with 2-wk washout, 10 cyclists completed 2.5 h of intervals followed by 4-h recovery feeding, provided 218 g protein, 435 g carbohydrate, and 79 g fat (protein enriched) or 34 g protein, 640 g carbohydrate, and 79 g fat (isocaloric control). The next morning, cyclists performed 10 maximal constant-work sprints on a Velotron cycle ergometer, each lasting approximately 2.5 min, at approximately 5-min intervals. Test validity was established and test reliability and the individual response to the protein-enriched condition estimated by 6 cyclists'repeating the intervals, recovery feeding, and performance test 2 wk later in the protein-enriched condition. During the 4-h recovery, the protein-enriched feeding had unclear effects on mean concentrations of plasma insulin, cortisol, and growth hormone, but testosterone was 25% higher (90% confidence limits, +/- 14%). Protein enrichment also reduced plasma creatine kinase by 33% (+/-38%) the next morning and reduced tiredness and leg-soreness sensations during the sprints, but effects on mean sprint power were unclear (-1.4%, +/-4.3%). The between-subjects trial-to-trial coefficient of variation in overall mean sprint power was 3.1% (+/-3.4%), whereas the variation in the protein-enriched condition was 5.9% (+/-6.9%), suggesting that individual responses to the protein-enriched treatment contributed to the unclear performance outcome. To conclude, protein-enriched recovery feeding had no clear effect on next-day performance.


Assuntos
Proteínas Alimentares/administração & dosagem , Exercício Físico/fisiologia , Músculo Esquelético/efeitos dos fármacos , Análise e Desempenho de Tarefas , Adulto , Ciclismo , Estudos Cross-Over , Carboidratos da Dieta/administração & dosagem , Relação Dose-Resposta a Droga , Humanos , Masculino , Músculo Esquelético/lesões , Músculo Esquelético/fisiologia , Resistência Física , Esforço Físico
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