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1.
Am J Sports Med ; 49(1): 183-192, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-33381989

RESUMO

BACKGROUND: Core stability is influential in the incidence of lower extremity injuries, including anterior cruciate ligament (ACL) injuries, but the effects of core strength training on the risk for ACL injury remain unclear. HYPOTHESIS: Core muscle strength training increases the knee flexion angle, hamstring to quadriceps (H:Q) coactivation ratio, and vastus medialis to vastus lateralis (VM:VL) muscle activation ratio, as well as decreases the hip adduction, knee valgus, and tibial internal rotation angles. STUDY DESIGN: Controlled laboratory study. METHODS: A total of 48 male participants were recruited and randomly assigned to either the intervention group (n = 32) or the control group (n = 16). Three-dimensional trunk, hip, knee, and ankle kinematic data and muscle activations of selected trunk and lower extremity muscles were obtained while the participants performed side-step cutting. The core endurance scores were measured before and after training. Two-way analyses of variance were conducted for each dependent variable to determine the effects of 10 weeks of core strength training. RESULTS: The trunk endurance scores in the intervention group significantly increased after training (P < .05 for all comparisons). The intervention group showed decreased knee valgus (P = .038) and hip adduction angles (P = .032) but increased trunk flexion angle (P = .018), rectus abdominis to erector spinae coactivation ratio (P = .047), H:Q coactivation ratio (P = .021), and VM:VL activation ratio (P = .016). In addition, the knee valgus angle at initial contact was negatively correlated with the VM:VL activation ratio in the precontact phase (R2 = 0.188; P < .001) but was positively correlated with the hip adduction angle (R2 = 0.120; P < .005). No statistically significant differences were observed in the trunk endurance scores, kinematics, and muscle activations for the control group. CONCLUSION: Core strength training altered the motor control strategies and joint kinematics for the trunk and the lower extremity by increasing the trunk flexion angle, VM:VL activation ratio, and H:Q activation ratio and reducing the knee valgus and hip adduction angles. CLINICAL RELEVANCE: Training core muscles can modify the biomechanics associated with ACL injuries in a side-step cutting task; thus, core strength training might be considered in ACL injury prevention programs to alter the lower extremity alignment in the frontal plane and muscle activations during sports-related tasks.


Assuntos
Músculos Abdominais/fisiologia , Lesões do Ligamento Cruzado Anterior/terapia , Extremidade Inferior/fisiologia , Treinamento de Resistência , Tronco/fisiologia , Adulto , Lesões do Ligamento Cruzado Anterior/prevenção & controle , Fenômenos Biomecânicos , Humanos , Articulação do Joelho , Masculino , Amplitude de Movimento Articular , Fatores de Risco
2.
Sports Health ; 13(1): 37-44, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-32903164

RESUMO

CONTEXT: Plyometric training has been shown to be beneficial in adolescent overhead athletes. However, existing research on the effects of plyometrics on sport performance has been limited. OBJECTIVE: To systematically review the current literature to investigate whether plyometric training intervention improves upper- and lower-body sport performance. DATA SOURCES: Two electronic databases (MEDLINE and Web of Science) were searched using specific Medical Subject Headings (MeSH) terms up to February 2019, and hand-searching was performed by looking to relevant studies that were cited in other studies. STUDY SELECTION: A total of 932 items were identified and were further assessed for the eligibility in the systematic review. For a study to be eligible, each of the following inclusion criteria had to be met: (1) participants were aged 13 to 18 years and selected from a sports or athletic population and the study (2) involved the evaluation of a plyometric training intervention with an aim to improve sports performance; (3) must have included a control intervention and/or control group; (4) included a quantitative objective measure of sport performance variables concerning throwing, jumping, running, and sprinting; and (5) was published in English. STUDY DESIGN: Systematic review. LEVEL OF EVIDENCE: Level 3. DATA EXTRACTION: A first screening was conducted based on title and abstract of the articles. In the second screening, the full text of the remaining articles was evaluated for the fulfillment of the inclusion criteria. RESULTS: A total of 14 studies were included in this review. The methodological quality of the included studies ranged from low to moderate. There is moderate evidence that plyometric training intervention improves throwing and jumping performances. There is also preliminary evidence that plyometric training intervention improves sprint performance. CONCLUSION: The current evidence suggests that sport performance consisting of throwing capacity, jumping ability, and sprint performance significantly improved due to plyometric training interventions in adolescent overhead athletes.


Assuntos
Desempenho Atlético/fisiologia , Exercício Pliométrico , Esportes Juvenis/fisiologia , Adolescente , Humanos , Extremidade Inferior/fisiologia , Corrida/fisiologia , Extremidade Superior/fisiologia
3.
PLoS One ; 15(12): e0243917, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33362223

RESUMO

The aim of the present clinical trial is to evaluate the effectiveness of neuromuscular versus classical strength-resistance training as part of a cardiac rehabilitation programme in patients following acute coronary syndrome. The study is designed as a double-blinded, randomised, and controlled clinical trial. Thirty participants suffering from acute coronary syndrome who meet our inclusion criteria will be recruited by a private tertiary hospital. The intervention group will follow 20 sessions of a cardiac rehabilitation programme divided into two parts: aerobic training and neuromuscular strength-resistance training. The control group will complete the same aerobic training as well as a classical strength-resistance training workout programme. The primary outcome of the study will be the mean difference in change from baseline in the Incremental Shuttle Walking Test. The secondary outcomes will be the cardiorespiratory fitness of the patients (assessed by means of the Chester Step Test), lower-limb performance (assessed with the 30-Second Chair Stand Test and Single-Leg Squat Test), lower-limb strength (hip flexor handheld dynamometry), sexual dysfunction assessment (Sex Health Inventory for Men) and quality of life (EQ-5D-5L). This work will provide evidence for the effectiveness of a neuromuscular versus a classic strength-training programme in terms of cardiorespiratory fitness, lower-limb performance capacities and quality of life, in cardiac patients. The data obtained could lead to more effective and functional workouts which, in turn, may enhance the speed at which these patients can return to their everyday activities of life and improve the efficiency of their movement patterns and heart responses. Furthermore, patients may find neuromuscular workout routines more motivating and engaging, thus encouraging them to adopt healthier lifestyle patterns.


Assuntos
Síndrome Coronariana Aguda/reabilitação , Força Muscular/fisiologia , Músculo Esquelético/fisiologia , Treinamento de Resistência , Síndrome Coronariana Aguda/fisiopatologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Teste de Esforço , Feminino , Humanos , Extremidade Inferior/fisiologia , Masculino , Pessoa de Meia-Idade , Aptidão Física/fisiologia , Qualidade de Vida , Resultado do Tratamento , Adulto Jovem
4.
J Vis Exp ; (162)2020 08 25.
Artigo em Inglês | MEDLINE | ID: mdl-32925877

RESUMO

Gait termination caused by unexpected stimulus is a common occurrence in everyday life. This study presents a protocol to investigate the lower-limb biomechanical changes that occur during unplanned gait termination (UGT) under different walking speeds. Fifteen male participants were asked to perform UGT on a walkway at normal walking speed (NWS) and fast walking speed (FWS), respectively. A motion analysis system and plantar pressure platform were applied to collect lower-limb kinematic and plantar pressure data. Paired-sampled T-test was used to examine the differences in lower-limb kinematics and plantar pressure data between two walking speeds. The results showed larger range of motion in the hip, knee, and ankle joints in the sagittal plane as well as plantar pressure in forefoot and heel regions during UGT at FWS when compared with NWS. With the increase in walking speed, subjects exhibited different lower-limb biomechanical characteristics that show FWS associated with greater potential injury risks.


Assuntos
Extremidade Inferior/fisiologia , Velocidade de Caminhada/fisiologia , Adulto , Fenômenos Biomecânicos/fisiologia , Calibragem , Humanos , Masculino , Movimento (Física) , Pressão , Amplitude de Movimento Articular
5.
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
6.
Sports Biomech ; 19(6): 723-737, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32942954

RESUMO

The aim of this study was to understand if and how surface-induced vibrations and road bike damping affect short-term neuromuscular performance in cycling. Thirty cyclists (mass 75.9 ± 8.9 kg, height 1.82 ± 0.05 m, Vo2max 63.0 ± 6.8 ml/min/kg) performed steady-state and maximum effort tests with and without vibration exposure (front dropout: 44 Hz, 4.1 mm; rear dropout: 38 Hz, 3.5 mm) on a damped and a nondamped bike. Transmitted accelerations to the musculoskeletal system, activation of lower extremity muscles (gast. med., soleus, vast. med., rec. fem.) and upper body muscles (erec. spinae, deltoideus, tric. brachii), oxygen uptake, heart rate and crank power output were measured. The main findings indicate a transmission of vibration to the whole body, but since no major propulsive muscles increase their activation with vibration, the systemic energy demand increases only marginally with vibration. Damping reduces vibrations at the upper body, which indicates an increase in comfort, but has no effect on the vibration transfer to the lower extremities. Therefore, road bike damping does not affect neuromuscular response of the propulsive muscle groups and energy demand. Consequently, short-term power output does not increase with damping.


Assuntos
Desempenho Atlético/fisiologia , Ciclismo/fisiologia , Meio Ambiente , Músculo Esquelético/fisiologia , Vibração , Aceleração , Fenômenos Biomecânicos , Estudos Transversais , Frequência Cardíaca/fisiologia , Humanos , Extremidade Inferior/fisiologia , Masculino , Músculo Esquelético/inervação , Consumo de Oxigênio/fisiologia , Tronco/fisiologia , Extremidade Superior/fisiologia
7.
J Sports Med Phys Fitness ; 60(8): 1072-1080, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32955833

RESUMO

BACKGROUND: This study aims at describing and comparing each other male and female soccer players kicking instep a stationary ball. The different measures we collected by the 3D motion capture system Movit G1 and the High-Speed Camera (240 fps) were considered as dependent variables, whereas the gender was considered as the independent one. METHODS: Twenty soccer well trained non-professional players: 10 men (age: 25.3±6.5 yrs; height 1.80±0.07 m; body mass 76.9±13.2 kg) and 10 women (age: 19±3.34 yrs; height 1.64±0.07 m; body mass 58.2±7.2 kg) volunteered to participate in the study. RESULTS: Gender differences were found, with a statistical significance (P<0.05) or interesting magnitude (Cohen d>0.5). The most relevant ones were the differences in hip extension of the kicking leg when the foot of the supporting one touches the ground, just before the impact on the ball (independent sample t-Test; P=0.03; Cohen d=1.64) and the speed of the ball, reached immediately after kicking (P<0.001;d=1.23). CONCLUSIONS: These results, together with the greater pelvic acceleration shown by men compared to women, highlight the need to develop a gender-differentiated training model, in order to customize the kicking technique in women and to reduce the likelihood, currently higher than for men, of kicking related injuries.


Assuntos
Extremidade Inferior/fisiologia , Futebol/fisiologia , Aceleração , Adulto , Fenômenos Biomecânicos , Feminino , Pé/fisiologia , Quadril/fisiologia , Humanos , Joelho/fisiologia , Masculino , Pelve/fisiologia , Caracteres Sexuais , Fatores Sexuais , Estudos de Tempo e Movimento , Adulto Jovem
8.
Apunts, Med. esport (Internet) ; 55(207): 89-95, jul.-sept. 2020. ilus, tab, graf
Artigo em Inglês | IBECS | ID: ibc-194709

RESUMO

INTRODUCTION: Age and sport specialization are two of the most important factors that can impact an athlete's flexibility, but their influence during adolescence in youth athletics hasn’t yet been investigated. MATERIAL AND METHODS: Retrospective analysis of the lower limb flexibility assessments in the athletics squad of a full-time sports academy in the Middle East for nine consecutive seasons (2006/07 to 2014/15). Flexibility data were analyzed for eight lower limb muscle groups (mean value±standard deviation) in four athletics events (throws, sprints & jumps, distance running and non-specialized) and seven age groups (categorized yearly from under 13 to above 18 years old). Total lower limb flexibility (TF) was calculated by summating all individual muscle group values and comparisons were made between age groups and athletics events with statistical significance set at p < 0.05. RESULTS: 127 adolescent athletes (age = 15.4 ± 1.8 years) completed, in total, 604 flexibility tests. No statistically significant differences between right and left were found for any muscle (p > 0.05). A weak inverse correlation (r = -0.21, p < 0.001) was found between age and TF, with no significant changes in hamstrings, adductors and hip flexors (p > 0.05). Throwers were found to be significantly less flexible (1091 ± 93) than distance runners (1227 ± 95), sprints & jumps (1186 ± 80) and non-specialized athletes (1178 ± 78); distance runners displayed greater hip external rotators flexibility than any other group (p < 0.01), and up to 78% more than throwers. CONCLUSIONS: this research confirmed that throwers were the least flexible of all events in youth athletics. Overall lower limb flexibility appears to decrease during adolescence, although hamstrings, adductors and hip flexors remained unchanged


No disponible


Assuntos
Humanos , Masculino , Criança , Adolescente , Atletas , Extremidade Inferior/fisiologia , Esforço Físico/fisiologia , Atletismo/fisiologia , Estudos Retrospectivos , Dinamômetro de Força Muscular , Análise de Variância
9.
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
10.
PLoS One ; 15(8): e0238247, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32853239

RESUMO

Switching different gait according to different movements is an important direction in the study of exoskeleton robot. Identifying the movement intention of the wearer to control the gait planning of the exoskeleton robot can effectively improve the man-machine interaction experience after the exoskeleton. This paper uses a support vector machine (SVM) to realize wearer's motion posture recognition by collecting sEMG signals on the human surface. The moving gait of the exoskeleton is planned according to the recognition results, and the decoding intention signal controls gait switching. Meanwhile, the stability of the planned gait during the movement was analyzed. Experimental results show that the sEMG signal decoding human motion intentional, and control exoskeleton robot gait switching has good accuracy and real-time performance. It helps patients to complete rehabilitation training more safely and quickly.


Assuntos
Marcha/fisiologia , Extremidade Inferior/fisiologia , Eletromiografia/métodos , Exoesqueleto Energizado , Humanos , Movimento (Física) , Movimento/fisiologia , Robótica/métodos , Máquina de Vetores de Suporte
11.
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
12.
PLoS One ; 15(8): e0237841, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32813733

RESUMO

To function effectively, a lower limb prosthetic socket must remain securely coupled to the residual limb during walking, running and other activities of daily living; this coupling is referred to as suspension. When this coupling is insufficient longitudinal pistoning of the socket relative to the residual limb occurs. Increasing friction of the socket/liner interface may improve socket suspension and textured sockets may be fabricated relatively easily with 3D printing. The aim of this study was to investigate longitudinal displacement of sockets with different types of textures under two suspension conditions: passive suction and active vacuum. In order to do this, we developed a mock residual limb and mechanical testing protocol. Prosthetic sockets, 14 textured sockets and an Original Squirt-Shape (OSS) Socket, were fabricated from polypropylene copolymer using the Squirt-Shape™ 3D Printer and compared to a smooth socket thermoformed from polypropylene copolymer. Sockets were mounted onto a dual durometer mock residual limb and subjected to four levels of distraction forces (100 N, 250 N, 500 N and 650 N) using a hydraulic material testing system. There was a statistically significant three-way interaction between suspension, force level and texture (p < 0.0005). Longitudinal displacements between textured and reference sockets, for all force levels and both suspension conditions, were significantly different (p < 0.0005). Using these newly developed mechanical testing protocols, it was demonstrated that texturing of polypropylene copolymer sockets fabricated using Squirt-Shape significantly decreased longitudinal displacements compared to a smooth socket. However, none of the novel textured sockets significantly reduced longitudinal displacement compared to the OSS socket under passive suction suspension.


Assuntos
Extremidade Inferior/fisiologia , Teste de Materiais , Fenômenos Mecânicos , Desenho de Prótese , Processamento de Imagem Assistida por Computador , Sucção , Vácuo
13.
Am J Physiol Regul Integr Comp Physiol ; 319(2): R142-R147, 2020 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-32663039

RESUMO

Earlier reports suggest that limb venous distension evokes reflex increases in muscle sympathetic nerve activity (MSNA) and blood pressure (BP) (i.e., venous distension reflex). Our recent report also shows that suction of arterially occluded limb evokes venous distension reflex. We postulate that the venous distension reflex contributes to autonomic responses to orthostatic stress. In this study, we hypothesized that orthostatic tolerance would be linked to the MSNA response seen with lower limb suction. Fifteen healthy subjects were tested in the supine position. Negative pressure (-100 mmHg) was applied on an arterially occluded lower limb for 2 min. MSNA from the peroneal nerve in the limb not exposed to suction, ECG, and BP (Finometer) was recorded throughout the study. Limb occlusion without suction was used as a control trial. In a separate visit, the individual's orthostatic tolerance was assessed using a graded lower body negative pressure (LBNP) tolerance test. Mean arterial BP and MSNA (18.6 ± 1.9 to 23.6 ± 2.0 bursts/min) significantly (both P < 0.05) increased during limb suction. Orthostatic tolerance index positively correlated (R = 0.636, P = 0.011) with the MSNA response seen with suction during occlusion. Since the venous distension reflex strength correlates with the level of orthostatic tolerance, we speculate that lower-limb venous distension reflex engagement increases the sympathetic responses during orthostatic challenge and serves to maintain BP with postural stress.


Assuntos
Barorreflexo/fisiologia , Pressão Sanguínea/fisiologia , Extremidade Inferior/fisiologia , Reflexo/fisiologia , Sistema Nervoso Simpático/fisiologia , Adulto , Feminino , Frequência Cardíaca/fisiologia , Humanos , Pressão Negativa da Região Corporal Inferior , Masculino , Fluxo Sanguíneo Regional
14.
J Electromyogr Kinesiol ; 53: 102441, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32629410

RESUMO

In this study, we investigated the effect of walker type on gait pattern characteristics comparing normal gait (NG), gait with a regular walker (RW), and gait with a newly developed walker with vertical moveable handlebars, the Crosswalker (CW). Partial weight bearing (PWB) of the feet, peak joint angles and largest Lyapunov exponent (λmax) of the lower extremities (hip, knee, ankle) in the sagittal plane, and gait parameters (gait velocity, stride length, cadence, stride duration) were determined for 18 healthy young adults performing 10 walking trials for each walking condition. Assistive gait with the CW improved local dynamic stability in the lower extremities (hip, knee, ankle) compared with RW and was not significantly different from NG. However, peak joint angles and stride characteristics in CW were different from NG. The PWB on the feet was lower with the RW (70.3%) compared to NG (82.8%) and CW (80.9%). This improved stability may be beneficial for the elderly and patients with impaired gait. However, increased PWB is not beneficial for patients during the early stages of rehabilitation.


Assuntos
Marcha/fisiologia , Músculo Esquelético/fisiologia , Andadores/tendências , Suporte de Carga/fisiologia , Adulto , Fenômenos Biomecânicos/fisiologia , Feminino , Voluntários Saudáveis , Humanos , Extremidade Inferior/fisiologia , Masculino , Andadores/normas , Caminhada/fisiologia , Adulto Jovem
15.
J Sports Sci ; 38(20): 2382-2389, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32600126

RESUMO

Elliptical trainers that increase the inter-pedal distance may have potential benefits for knee osteoarthritis by decreasing the amount of knee varus. Modifying elliptical trainers with a converging footpath and reduced inter-pedal distance may be beneficial for reducing anterior knee pathology risk by decreasing knee valgus angles. Twenty-one college students participated in a single testing session. Participants exercised on two different elliptical trainers, one modified with a converging footpath and reduced inter-pedal width, and a standard elliptical trainer. Participants exercised for 2 min at three ramps incline at 120 strides per minute and constant work rate. Three-dimensional kinematics and electromyography of the dominant lower limb were recorded. Multiple 2 × 3 (Elliptical x Incline) ANOVAs with Bonferroni corrections were used to compare the two elliptical trainers at each incline for kinematics and muscle activity. The modified elliptical trainer displayed significantly decreased peak knee valgus (p = 0.031, η p 2 = 0.234 ), peak knee flexion (p = 0.006, η p 2 = 0.246 ), and interactions for peak knee flexion (p = 0.001, η p 2 = 0.250 ) and vastus lateralis (p < 0.01, η p 2 = 0.380 ) muscle activity compared to the standard elliptical trainer. The decreased peak knee valgus and flexion angles could be beneficial for reducing long-term injury risk for anterior knee pathologies.


Assuntos
Extremidade Inferior/fisiologia , Músculo Esquelético/fisiologia , Equipamentos Esportivos , Fenômenos Biomecânicos , Eletromiografia , Desenho de Equipamento , Feminino , Marcha/fisiologia , Quadril/fisiologia , Humanos , Joelho/fisiologia , Masculino , Estudos de Tempo e Movimento , Adulto Jovem
16.
Hu Li Za Zhi ; 67(3): 48-55, 2020 Jun.
Artigo em Chinês | MEDLINE | ID: mdl-32495329

RESUMO

BACKGROUND: Falls are a very common problem in older adults. Improving lower extremity muscle strength is the primary objective of fall-prevention programs. PURPOSE: The aim of the study was to evaluate the effects of the Otago Exercise Program (OEP) on the lower extremity muscle strength of residents living in a long-term care institution. METHODS: In this repeated measurement study, participants were allocated into either the experimental group (EG) or the control group (CG). All of the participants maintained normal activities, and EG participants were additionally enrolled in a 6-month group OEP led by a physiotherapist. The OEP, comprising warm-up exercises, strength training, balance training, and walking training, requires about 45 minutes per session, 3 times a week. A total of 78 OEP sessions were performed during the 6-month intervention. A 30-Second Sit-to-Stand Test and lower extremity muscle strength measurements were performed at baseline, after 3 months, and after 6 months. RESULTS: The twenty participants in this study had a mean age over 80 years and were recruited from a long-term care institution in southern Taiwan. There were ten participants in each group, and the mean total OEP session attendance for EG participants was 92.8%. Although the EG had lower extremity muscle strength than the CG at baseline, the EG had achieved significant improvements in the muscle strength values for the knee extensor, knee flexor, ankle plantar flexors, and dorsiflexors after 6 months (group x time interaction, p < .05). In addition, the results of the 30-second sit-to-stand test for the EG were poor at baseline and significantly better after 6 months, while the results for the CG worsened between baseline and 6 months. CONCLUSIONS / IMPLICATIONS FOR PRACTICE: The results of this study support that participating in a group-based OEP three times per week over 6 months effectively improves lower extremity muscle strength in older adults. Therefore, OEP should be incorporated into fall-prevention programs organized in long-term care institutions.


Assuntos
Terapia por Exercício , Extremidade Inferior/fisiologia , Força Muscular/fisiologia , Instituições Residenciais , Idoso de 80 Anos ou mais , Humanos , Assistência de Longa Duração , Avaliação de Programas e Projetos de Saúde , Taiwan
17.
J Electromyogr Kinesiol ; 53: 102436, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32505988

RESUMO

This systematic review and meta-analysis examined differences in lower extremity neural excitability between ankles with and without chronic ankle instability (CAI). We searched the literature for studies that compared corticomotor or spinal reflexive excitability between a CAI group and controls or copers, or between limbs of a CAI group. Random effects meta-analyses calculated pooled effect sizes for each outcome. Nineteen studies were included. Meta-analyses of motor thresholds of the fibularis longus (Z = 1.17, P = 0.24) and soleus (Z = 0.47, P = 0.64) exhibited no differences between ankles with and without CAI. Pooled data indicate that ankles with CAI had reduced soleus spinal reflexive excitability (Z = 2.18, P = 0.03) and significantly less modulation of the soleus (Z = 6.96, P < 0.01) and fibularis longus (Z = 4.75, P < 0.01) spinal reflexive excitability when transitioning to more challenging stances. Pre-synaptic inhibition was facilitated in ankles with CAI (Z = 4.05, P < 0.01), but no difference in recurrent inhibition existed (Z = 1.50, P = 0.13). Soleus spinal reflexive activity is reduced in those with CAI. Reduced ability of ankles with CAI to modulate soleus and fibularis longus reflexive activity may contribute to impaired balance.


Assuntos
Articulação do Tornozelo/fisiologia , Potencial Evocado Motor/fisiologia , Instabilidade Articular/fisiopatologia , Extremidade Inferior/fisiologia , Músculo Esquelético/fisiologia , Traumatismos do Tornozelo/diagnóstico , Traumatismos do Tornozelo/fisiopatologia , Estudos de Casos e Controles , Humanos , Instabilidade Articular/diagnóstico , Reflexo/fisiologia , Estimulação Magnética Transcraniana/métodos
18.
PLoS One ; 15(6): e0234140, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32492058

RESUMO

BACKGROUND: Diminished somatosensory function is a critical age-related change which is related to postural instability in the older population. Footwear is a cost-effective way to modulate the postural stability by altering sensorimotor inputs via mechanoreceptors on the plantar surface of the feet. Compared to insoles with indentions in the entire surface, we innovatively developed a textured insole with site-specific nodulous protrudous. This study thus aimed to investigate the immediate effect of the nodulous insole and supporting surface condition on static postural stability and lower limb muscle activation for healthy older women. METHODS: This is a single-session study with repeated measurements. Twenty-three healthy older women stood on the firm (i.e., concrete floor) and foam surfaces with their eyes open in the three footwear conditions, namely barefoot, plain shoes and shoes with an innovative textured insole, for 30 seconds. Static postural sway and muscle activation of biceps femoris (BF), vastus lateralis (VL), tibialis anterior (TA), and lateral gastrocnemius (LG) of the dominant leg were measured during each testing condition. RESULTS: Compared to a firm surface, standing on the foam could significantly increase the body sway and lower limb muscle activation (p<0.05). When standing on the foam, compared to barefoot, wearing footwear significantly decreased the VL and TA muscle activation and minimize the postural sway in medial-lateral and anterior-posterior direction, while the influence is larger for the shoes with nodulous insloe compared to the plain shoes. No significant differences between the footwear conditions for static stability and muscle activation were observed on firm surface condition. CONCLUSIONS: For older women, footwear could improve the postural stability in the unstable surface, particularly the footwear with nodulous insole, with the underlying mechanism as enhancing the mechanoreceptors on the plantar surface of the feet.


Assuntos
Órtoses do Pé , Extremidade Inferior/fisiologia , Equilíbrio Postural/fisiologia , Idoso , Eletromiografia , Feminino , Humanos , Pessoa de Meia-Idade , Sapatos , Posição Ortostática
19.
Int J Sports Med ; 41(11): 729-735, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32492733

RESUMO

Side differences in the limb symmetry index during hop tests have been rarely investigated in uninjured athletes. Unknown differences can result in false interpretation of hop tests and affect return to sport decision. Hypothesis was that un-injured athletes in Judo and Taekwondo have side differences in hop test and that asymmetries can be predicted based on the athletes fighting display. Differences, risk relationships were analyzed using the chi-squared test and the odds ratio. A two-tailed p value of<0.05 was considered statistically significant. 115 athletes from the national teams were included (mean age 18.4 years; range 13-27 years). 93, 97.4 and 98.3% did not have symmetric hop distance for three hop tests. Up to a quarter did not reach a limb symmetry index of>90. Moreover, 57.4% (n=66) reached longer jumping distance with the standing leg. Ignoring such pre-existent side differences in evaluation of hop tests and not knowing which limb was dominant prior the injury, can lead to premature or delayed return to sports in the rehabilitation process. Therefore, it might be helpful to refer to individual jump lengths for each limb in case of injury by using hop tests in pre-season screening in professional athletes in Judo and Taekwondo.


Assuntos
Lateralidade Funcional , Extremidade Inferior/fisiologia , Artes Marciais/fisiologia , Adolescente , Adulto , Teste de Esforço/métodos , Feminino , Humanos , Extremidade Inferior/lesões , Masculino , Artes Marciais/lesões , Volta ao Esporte , Adulto Jovem
20.
J Sports Med Phys Fitness ; 60(7): 979-984, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32597615

RESUMO

BACKGROUND: Plyometric exercises are often used to develop lower limb strength and performance-related biomechanics such as leg stiffness. However, the effectiveness of plyometric training may depend on participants' own training and performance demands. The purpose of this study was to examine the effect of plyometric training on Reactive Strength Index (RSI) and leg stiffness (Kleg) on young athletes of different sports. METHODS: Forty eight female athletes (25 Taekwondo (TKD) and 23 rhythmic gymnastics (RG), mean±SD: age: 8.94±2.50 years; mass: 29.73±7.69 kg; height: 138.84±11.90 cm; training experience: 4.62±2.37 years) participated in this study. Participants were randomly assigned to experimental (PT, N.=24) and control (CG, N.=24) groups. The PT group followed a twice-weekly plyometric training program for 4 weeks. Plyometric drills lasted approximately 5-10 s, and at least 90 s rest was allowed after each set. To examine RSI, participants performed trials of five maximal CMJs. Submaximal hopping (20 hops) was performed in order to examine leg stiffness. RESULTS: Significant interaction effect was found for RSI and the post hoc analysis showed that RSI significantly increased by 35% (P=0.017) in RG athletes, whereas a significantly reduction by 28% (P=0.004) was revealed in TKD athletes. The interaction effect between time and group was statistically significant for Kleg (P<0.05) with Kleg significantly increasing by 31% (P=0.008) in TKD athletes, but remaining unchanged (P>0.05) in RG athletes. CONCLUSIONS: The results showed that the effect of a 4-week plyometric training program on RSI and leg stiffness is sport dependent. Further, the applied plyometric program was effective in reducing ground contact time and therefore increasing leg stiffness.


Assuntos
Ginástica/fisiologia , Extremidade Inferior/fisiologia , Artes Marciais/fisiologia , Força Muscular/fisiologia , Exercício Pliométrico/métodos , Adolescente , Desempenho Atlético/fisiologia , Fenômenos Biomecânicos , Criança , Feminino , Humanos , Movimento/fisiologia
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