RESUMEN
Enhancing peak landing forces and ensuring faster stabilization in the lower limbs during jumping activities can significantly improve performance and decrease the risk of injury among basketball players. This study aimed to compare the effects of unilateral (uPJT) and bilateral plyometric jump training (bPJT) programs on various performance measures, including countermovement jump (CMJ), squat jump (SJ), and single-leg land and hold (SLLH) test outcomes, assessed using force plates. A randomized multi-arm study design was employed, comprising two experimental groups (n = 25; uPJT and n = 25; bPJT) and one control group (n = 25), conducted with youth male regional-level basketball players (16.3 ± 0.6 years old). Participants underwent assessment twice, both before and after an 8-week intervention training period. The uPJT program exclusively involved plyometric drills (e.g., vertical jump exercises; horizontal jump exercises) focusing on single-leg exercises, whereas the bPJT program utilized drills involving both legs simultaneously. The outcomes analyzed included CMJ peak landing force, CMJ peak power, SJ peak force, SJ maximum negative displacement, SLLH time to stabilization, and SLLH peak landing force. The control group exhibited significantly greater SLLH time to stabilization compared to both the uPJT (p < 0.001) and bPJT (p < 0.030) groups. Additionally, time to stabilization was also significantly higher in bPJT than in uPJT (p = 0.042). Comparisons between groups in regards SLLH peak landing force after intervention revealed that the value was significantly smaller in uPJT than in bPJT (p = 0.043) and control (p < 0.001). In the remaining outcomes of CMJ and SJ, both uPJT and bPJT showed significant improvement compared to the control group (p > 0.05), although there was no significant difference between them. In conclusion, our study suggests that utilizing uPJT is equally effective as bPJT in enhancing performance in bilateral jump tests. However, it significantly outperforms bPJT in improving time to stabilization and peak landing forces during single-leg land and hold test. uPJT could be advantageous not for maximizing performance but also for potentially decreasing injury risk by enhancing control and balance during single-leg actions, which are common in basketball.
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Rendimiento Atlético , Baloncesto , Ejercicio Pliométrico , Humanos , Baloncesto/fisiología , Masculino , Ejercicio Pliométrico/métodos , Adolescente , Rendimiento Atlético/fisiología , Extremidad Inferior/fisiología , Prueba de Esfuerzo/métodos , Fenómenos Biomecánicos , Fuerza Muscular/fisiología , Pierna/fisiología , Acondicionamiento Físico Humano/métodos , Acondicionamiento Físico Humano/fisiologíaRESUMEN
Running jumps that depart the ground from two feet require momenta redirection upward from initial momenta that are primarily horizontal. It is not known how each leg generates backward and upward impulses from ground reaction forces to satisfy this mechanical objective when jumping to maximize height. We examined whole-body linear momentum control strategies during these two-foot running jumps by uncovering the roles of each leg in impulse generation. 3D motion capture and force plates were used to record 14 male basketball players performing two-foot running jumps towards an adjustable basketball hoop. Total ground contact phase started from the first leg ground contact and ended at takeoff and was divided into center of mass descent and ascent subphases. During the total ground contact phase, all participants generated significantly more upward impulse with the first leg and ten participants generated significantly more backward impulse with the first leg compared to the second leg. During the descent subphase, all participants generated significantly more upward and backward impulses with the first leg. During the ascent subphase, all but one participant generated significantly more backward impulse with the second leg. In addition to group-level statistics, participant-specific strategies were described. Overall, this study revealed the fundamental whole-body momentum control strategies used in two-foot running jumps and supports future research into optimal jump techniques and training interventions that respect the need to satisfy the mechanical objectives of the movement.
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Baloncesto , Carrera , Humanos , Masculino , Baloncesto/fisiología , Carrera/fisiología , Fenómenos Biomecánicos , Pie/fisiología , Adulto , Adulto Joven , Pierna/fisiologíaRESUMEN
While interest in using wearable sensors to measure infant leg movement is increasing, attention should be paid to the characteristics of the sensors. Specifically, offset error in the measurement of gravitational acceleration (g) is common among commercially available sensors. In this brief report, we demonstrate how we measured the offset and other errors in three different off-the-shelf wearable sensors available to professionals and how they affected a threshold-based movement detection algorithm for the quantification of infant leg movement. We describe how to calibrate and correct for these offsets and how conducting this improves the reproducibility of results across sensors.
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Algoritmos , Pierna , Movimiento , Dispositivos Electrónicos Vestibles , Humanos , Movimiento/fisiología , Lactante , Pierna/fisiología , Calibración , Reproducibilidad de los Resultados , Monitoreo Fisiológico/instrumentación , Monitoreo Fisiológico/métodos , AceleraciónRESUMEN
Robotic locomotion in unstructured terrain demands an agile, adaptive, and energy-efficient architecture. To traverse such terrains, legged robots use rigid electromagnetic motors and sensorized drivetrains to adapt to the environment actively. These systems struggle to compete with animals that excel through their agile and effortless motion in natural environments. We propose a bio-inspired musculoskeletal leg architecture driven by antagonistic pairs of electrohydraulic artificial muscles. Our leg is mounted on a boom arm and can adaptively hop on varying terrain in an energy-efficient yet agile manner. It can also detect obstacles through capacitive self-sensing. The leg performs powerful and agile gait motions beyond 5 Hz and high jumps up to 40 % of the leg height. Our leg's tunable stiffness and inherent adaptability allow it to hop over grass, sand, gravel, pebbles, and large rocks using only open-loop force control. The electrohydraulic leg features a low cost of transport (0.73), and while squatting, it consumes only a fraction of the energy (1.2 %) compared to its conventional electromagnetic counterpart. Its agile, adaptive, and energy-efficient properties would open a roadmap toward a new class of musculoskeletal robots for versatile locomotion and operation in unstructured natural environments.
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Locomoción , Robótica , Robótica/métodos , Locomoción/fisiología , Humanos , Pierna/fisiología , Fenómenos Biomecánicos , Marcha/fisiología , Músculo Esquelético/fisiologíaRESUMEN
BACKGROUND: Sensitive measures to predict neuromotor outcomes from data collected early in infancy are lacking. Measures derived from the recordings of infant movement using wearable sensors may be a useful new technique. METHODS: We collected full-day leg movement of 41 infants in rural Guatemala across 3 visits between birth and 6 months of age using wearable sensors. Average leg movement rate and fuzzy entropy, a measure to describe the complexity of signals, of the leg movements' peak acceleration time series and the time series itself were derived. We tested the three measures for the predictability of infants' developmental outcome, Bayley Scales of Infant and Toddler Development III motor, language, or cognitive composite score assessed at 12 months of age. We performed quantile regressions with clustered standard errors, accounting for the multiple visits for each infant. RESULTS: Fuzzy entropy was associated with the motor composite score at the 0.5 quantiles; this association was not found for the other two measures. Also, no leg movement characteristic was associated with language or cognitive composite scores. CONCLUSION: We propose that the entropy of leg movement associated peak accelerations calculated from the wearable sensor data collected for a full-day can be considered as one predictor for infants' motor developmental outcome assessed with Bayley Scales of Infant and Toddler Development III at 12 months of age.
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Desarrollo Infantil , Población Rural , Dispositivos Electrónicos Vestibles , Humanos , Guatemala , Lactante , Femenino , Masculino , Desarrollo Infantil/fisiología , Pierna/fisiología , Recién Nacido , Movimiento/fisiología , Acelerometría/instrumentación , Desarrollo del LenguajeRESUMEN
The actions of the major human leg muscles are well established; however, the functions of these muscle actions during steady running remain unclear. Here, leg structures and mechanisms are considered in terms of their functions in meeting the task of a vehicle acting as an effective machine, supporting body weight during translation with low mechanical work demand and in supplying mechanical work economically. Legs are modelled as a sequence of linkages that predict muscle actions and reveal the varying muscle functions within the integrated leg. Work avoidance is achieved with isometric muscles and linkages that promote a sliding of the hip over the ground contact, resulting in an approximately horizontal path of the centre of mass. Economical work supply requires, for muscle with constrained power, shortening over the entire stance duration; this function is achieved by the hamstrings without disrupting the linkages resulting in work avoidance. In late stance, the two functions occur through coactivation of antagonistic muscles, providing one answer to Lombard's paradox. Quadriceps and hamstring tensions result in opposing moments about both hip and knee joints, but by doing so perform the independent yet complementary roles of work avoidance during translating weight support and economical work supply.
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Pierna , Músculo Esquelético , Carrera , Humanos , Carrera/fisiología , Músculo Esquelético/fisiología , Pierna/fisiología , Fenómenos BiomecánicosRESUMEN
Under simultaneous ambient temperature and postural stressors, integrated regional blood flow responses are required to maintain blood pressure and thermoregulatory homeostasis. The aim of the present study was to assess the effect of ambient temperature and body posture on regional regulation of microvascular blood flow, specifically in the arms and legs. Participants (N = 11) attended two sessions in which they experienced transient ambient conditions, in a climatic chamber. During each 60-min trial, ambient temperature increased from 15.7 (0.6) °C to 38.9 (0.6) °C followed by a linear decrease, and the participants were either standing or in a supine position throughout the trial; relative humidity in the chamber was maintained at 25.9 (6.6) %. Laser doppler flowmetry of the forearm (SkBFarm) and calf (SkBFcalf), and haemodynamic responses (heart rate, HR; stroke volume, SV; cardiac output, CO; blood pressure, BP), were measured continuously. Analyses of heart rate variability and wavelet transform were also conducted. SkBFarm increased significantly at higher ambient temperatures (p = 0.003), but not SkBFcalf. The standing posture caused lower overall SkBF in both regions throughout the protocol, regardless of temperature (p < 0.001). HR and BP were significantly elevated, and SV significantly lowered, in response to separate and combined effects of higher ambient temperatures and a standing position (all p < 0.05); CO remained unchanged. Mechanistic analyses identified greater sympathetic nerve activation, and higher calf myogenic activation at peak temperatures, in the standing condition. Mechanistically and functionally, arm vasculature responds to modulation from both thermoregulation and baroreceptor activity. The legs, meanwhile, are more sensitive to baroreflex regulatory mechanisms.
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Frecuencia Cardíaca , Hemodinámica , Postura , Flujo Sanguíneo Regional , Humanos , Masculino , Adulto , Presión Sanguínea , Adulto Joven , Femenino , Temperatura , Regulación de la Temperatura Corporal , Pierna/irrigación sanguínea , Pierna/fisiologíaRESUMEN
Background and Objectives: Bedridden patients are at a high risk of venous thromboembolism (VTE). Passive devices such as elastic compression stockings and intermittent pneumatic compression are common. Leg exercise apparatus (LEX) is an active device designed to prevent VTE by effectively contracting the soleus muscle and is therefore expected to be effective in preventing disuse of the lower limbs. However, few studies have been conducted on the kinematic properties of LEX. Therefore, this study aimed to compare the exercise characteristics of LEX with those of an ergometer, which is commonly used as a lower-limb exercise device, and examine its effect on the two domains of muscle activity and circulatory dynamics. Materials and Methods: This study used a crossover design in which each participant performed both exercises to evaluate the exercise characteristics of each device. Fifteen healthy adults performed exercises with LEX and an ergometer (Terasu Erugo, SDG Co., Ltd., Tokyo, Japan) for 5 min each and rested for 10 min after each exercise. Muscle activity was measured using surface electromyography (Clinical DTS, Noraxon, Scottsdale, AZ, USA), and circulatory dynamics were recorded using a non-invasive impedance cardiac output meter (Physioflow Enduro, Manatec Biomedical, Paris, France). The primary outcome was the mean percentage of maximum voluntary contraction (%MVC) of the soleus muscle during exercise. Results: The mean %MVC of the soleus muscle was significantly higher in the LEX group, whereas no significant differences were observed across the periods and sequences. Heart rate, stroke volume, and cardiac output increased during exercise and decreased thereafter; however, the differences between the devices were not significant. Conclusions: LEX may not only have a higher thromboprophylaxis effect, but also a higher effect on preventing muscle atrophy as a lower-extremity exercise device. Additionally, LEX could potentially be used safely in patients who need to be monitored for changes in circulatory dynamics.
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Estudios Cruzados , Músculo Esquelético , Humanos , Masculino , Femenino , Adulto , Músculo Esquelético/fisiología , Ejercicio Físico/fisiología , Ergometría/métodos , Ergometría/instrumentación , Electromiografía/métodos , Pierna/fisiología , Tromboembolia Venosa/prevención & controlRESUMEN
Humans exhibit unique skeletal muscle morphologies that are known to matter in upright bipedalism. However, their relevance to the ease of leg swing, which limits locomotion performance, remains unclear. Here, we aimed to examine muscle mass distribution within the human leg and the effect of each muscle on the ease of leg swing. We calculated the mass, center of mass position, and moment of inertia around the hip extension-flexion axis for all leg muscles by using a publicly available dataset of the 3D reconstruction of the musculoskeletal components in human male and female legs. The leg muscles showed a top-heavy-bottom-light tapering trend; muscles far from the hip joint tended to have smaller masses. Interestingly, however, the soleus exhibited sizable mass for its location. Consequently, the moment of inertia of the soleus was exceptionally greatest, accounting for approximately one-quarter of that of all muscles. These results indicate that compared to the other muscles the soleus muscle has a much larger effect on the leg moment of inertia and uniquely makes humans difficult to swing the leg, although the leg muscles basically show the top-heavy bottom-light tapering trend favoring the leg swing. Our findings highlight a novel functional consequence of human body evolution, suggesting that muscular enlargement for postural stability and endurance capacity has compromised the locomotion speed during the adaptation to bipedalism.
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Pierna , Músculo Esquelético , Humanos , Músculo Esquelético/fisiología , Masculino , Femenino , Pierna/fisiología , Pierna/anatomía & histología , Articulación de la Cadera/fisiología , Articulación de la Cadera/anatomía & histología , Adulto , Fenómenos Biomecánicos , Caminata/fisiología , Locomoción/fisiologíaRESUMEN
While resistance training promotes muscle hypertrophy and strength, accessibility of equipment is a barrier. This study evaluated a wearable VAriable Resistance Suit (VARS) as a novel and alternative method to achieve muscle strength improvement. It was hypothesized that by providing adjustable, bi-directional and speed dependent resistance, VARS can target specific muscles to improve muscle strength via an accessible and portable device. Twelve untrained healthy male adults (22.08 ± 4.1 years old) participated in an 8-week long resistance training using VARS to strengthen four muscles (biceps brachii, triceps brachii, biceps femoris, rectus femoris) of their non-dominant arm and leg using VARS. The results showed significant improvements in the muscle strength measured by isokinetic dynamometer - 49.9±9.6% increase in isokinetic force and 30.6±7.6% increase in isometric force. Muscle size and body composition were also assessed using ultrasound imaging and bioelectrical impedance analysis, which did not show significant changes. The study demonstrates the efficacy and feasibility of VARS as a resistance training tool to achieve muscle strength improvement and its potential extension to clinical populations.
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Voluntarios Sanos , Contracción Isométrica , Fuerza Muscular , Músculo Esquelético , Entrenamiento de Fuerza , Humanos , Masculino , Entrenamiento de Fuerza/métodos , Fuerza Muscular/fisiología , Adulto Joven , Contracción Isométrica/fisiología , Adulto , Músculo Esquelético/fisiología , Dinamómetro de Fuerza Muscular , Dispositivos Electrónicos Vestibles , Composición Corporal , Impedancia Eléctrica , Brazo/fisiología , Pierna/fisiologíaRESUMEN
Coordinative patterns require experience and learning to be acquired, producing movements that offer efficient solutions to various situations and involving certain degree of variability. This coordination variability implies functionality in movement, but it can be impacted by the type of sport practice from early years. The purpose of this work is to analyze the coordination variability and coordination patterns in a specific action such as single-leg landing in children practicing gymnastics, volleyball and non-sporting children. Thirty children (15 girls) performed 10 successful trials of single-leg landing from a height of 25 cm. A motion capture system (9 cameras) was used to capture 3D thigh and shank kinematics. To identify the significant effect of children's groups on coordination and coordination variability during single-leg landing, one-dimensional Statistical Parametric Mapping (SPM) was used. Regarding the coordination patterns, in the frontal plane, during the attenuation phase of single-leg landing, the control group exhibited a higher frequency of Anti-Phase with proximal dominancy compared to the sport groups (i.e., gymnastics, and volleyball). In addition, in the sagittal plane during the second peak phase, volleyball players exhibited a higher coordination variability than the gymnastics. The children in the control group showed a greater frequency of antiphasic movements, which indicates the influence of training at an early age, being a determining factor in the increase or not of variability.
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Gimnasia , Voleibol , Humanos , Niño , Femenino , Masculino , Fenómenos Biomecánicos , Desempeño Psicomotor/fisiología , Movimiento , Destreza Motora/fisiología , Pierna/fisiologíaRESUMEN
ABSTRACT: Fourel, L, Touzard, P, Fadier, M, Arles, L, Deghaies, K, Ozan, S, and Martin, C. Relationships between force-time curve variables and tennis serve performance in competitive tennis players. J Strength Cond Res 38(9): 1667-1674, 2024-Practitioners consider the role of the legs in the game of tennis as fundamental to achieve high performance. But, the exact link between leg actions and high-speed and accurate serves still lacks understanding. Here, we investigate the correlation between force-time curve variables during serve leg drive and serve performance indicators. Thirty-six competitive players performed fast serves, on 2 force plates, to measure ground reaction forces (GRF). Correlation coefficients describe the relationships between maximal racket head velocity, impact height, and force-time curve variables. Among all the variables tested, the elapsed time between the instants of maximal vertical and maximal anteroposterior GRF ( r = -0.519, p < 0.001) and the elapsed time between the instant of maximal anteroposterior GRF and ball impact ( r = -0.522, p < 0.001) are the best predictors of maximal racket velocity. Maximal racket head velocity did not significantly correlate with the mean or maximal vertical GRF or with the mean or maximum rate of vertical force development. The best predictor for impact height is the relative net vertical impulse during the concentric phase ( r = 0.772, p < 0.001). This work contributes to a better understanding of the mechanical demands of tennis serve motion and gives guidelines to improve players preparation and performance. Trainers should encourage their players to better synchronize their upward and forward pushing action during the serve to increase maximal racket head velocity. Players should also aim to improve their relative net vertical impulse to increase impact height through strength training and technical instructions.
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Rendimiento Atlético , Tenis , Humanos , Tenis/fisiología , Rendimiento Atlético/fisiología , Masculino , Adulto Joven , Fenómenos Biomecánicos , Adulto , Conducta Competitiva/fisiología , Adolescente , Pierna/fisiología , FemeninoRESUMEN
OBJECTIVE: This study explored the impact of one session of low-pressure leg blood flow restriction (BFR) during treadmill walking on dual-task performance in older adults using the neurovisceral integration model framework. METHODS: Twenty-seven older adults participated in 20-min treadmill sessions, either with BFR (100 mmHg cuff pressure on both thighs) or without it (NBFR). Dual-task performance, measured through light-pod tapping while standing on foam, and heart rate variability during treadmill walking were compared. RESULTS: Following BFR treadmill walking, the reaction time (p = 0.002) and sway area (p = 0.012) of the posture dual-task were significantly reduced. Participants exhibited a lower mean heart rate (p < 0.001) and higher heart rate variability (p = 0.038) during BFR treadmill walking. Notably, BFR also led to band-specific reductions in regional brain activities (theta, alpha, and beta bands, p < 0.05). The topology of the EEG network in the theta and alpha bands became more star-like in the post-test after BFR treadmill walking (p < 0.005). CONCLUSION: BFR treadmill walking improves dual-task performance in older adults via vagally-mediated network integration with superior neural economy. This approach has the potential to prevent age-related falls by promoting cognitive reserves.
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Frecuencia Cardíaca , Caminata , Humanos , Anciano , Masculino , Femenino , Caminata/fisiología , Frecuencia Cardíaca/fisiología , Prueba de Esfuerzo , Encéfalo/fisiología , Encéfalo/diagnóstico por imagen , Encéfalo/irrigación sanguínea , Flujo Sanguíneo Regional/fisiología , Desempeño Psicomotor/fisiología , Pierna/fisiologíaRESUMEN
Cardiac output (QÌC) and leg blood flow (QÌLEG) can be measured simultaneously with high accuracy using transpulmonary and femoral vein thermodilution with a single-bolus injection. The invasive measure has offered important insight into leg hemodynamics and blood flow distribution during exercise. Despite being the natural modality of exercise in humans, there has been no direct measure of QÌLEG while running in humans. We sought to determine the feasibility of the thermodilution technique for measuring QÌLEG and conductance during high-intensity running, in an exploratory case study. A trained runner (30 years male) completed two maximal incremental tests on a cycle ergometer and motorized treadmill. QÌLEG and QÌC were determined using the single-bolus thermodilution technique. Arterial and venous blood were sampled throughout exercise, with continuous monitoring of metabolism, intra-arterial and venous pressure, and temperature. The participant reached a greater peak oxygen uptake (VÌO2peak) during running relative to cycling (74 vs. 68 mL/kg/min) with comparable QÌLEG (19.0 vs. 19.5 L/min) and QÌC (27.4 vs. 26.2 L/min). Leg vascular conductance was greater during high-intensity running relative to cycling (82 vs. 70 mL/min/mmHg @ ~80% VÌO2peak). The "beat phenomenon" was apparent in femoral flow while running, producing large gradients in conductance (62-90 mL/min/mmHg @ 70% VÌO2peak). In summary, we present the first direct measure of QÌLEG and conductance in a running human. Our findings corroborate several assumptions about QÌLEG during running compared with cycling. Importantly, we demonstrate that using thermodilution in running exercise can be completed effectively and safely.
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Gasto Cardíaco , Pierna , Consumo de Oxígeno , Flujo Sanguíneo Regional , Carrera , Termodilución , Humanos , Termodilución/métodos , Gasto Cardíaco/fisiología , Carrera/fisiología , Masculino , Pierna/irrigación sanguínea , Pierna/fisiología , Adulto , Consumo de Oxígeno/fisiología , Flujo Sanguíneo Regional/fisiología , Prueba de Esfuerzo/métodosRESUMEN
Transspinal (or transcutaneous spinal cord) stimulation is a promising noninvasive method that may strengthen the intrinsic spinal neural connectivity in neurological disorders. In this study we assessed the effects of cervical transspinal stimulation on the amplitude of leg transspinal evoked potentials (TEPs), and the effects of lumbosacral transspinal stimulation on the amplitude of arm TEPs. Control TEPs were recorded following transspinal stimulation with one cathode electrode placed either on Cervical 3 (21.3 ± 1.7 mA) or Thoracic 10 (23.6 ± 16.5 mA) vertebrae levels. Associated anodes were placed bilaterally on clavicles or iliac crests. Cervical transspinal conditioning stimulation produced short latency inhibition of TEPs recorded from left soleus (ranging from - 6.11 to -3.87% of control TEP at C-T intervals of -50, -25, -20, -15, -10, 15 ms), right semitendinosus (ranging from - 11.1 to -4.55% of control TEP at C-T intervals of -20, -15, 15 ms), and right vastus lateralis (ranging from - 13.3 to -8.44% of control TEP at C-T intervals of -20 and - 15 ms) (p < 0.05). Lumbosacral transspinal conditioning stimulation produced no significant effects on arm TEPs. We conclude that in the resting state, cervical transspinal stimulation affects the net motor output of leg motoneurons under the experimental conditions used in this study. Further investigations are warranted to determine whether this protocol may reactivate local spinal circuitry after stroke or spinal cord injury and may have a significant effect in synchronization of upper and lower limb muscle synergies during rhythmic activities like locomotion or cycling.
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Brazo , Potenciales Evocados Motores , Pierna , Estimulación de la Médula Espinal , Humanos , Adulto , Masculino , Estimulación de la Médula Espinal/métodos , Femenino , Pierna/fisiología , Brazo/fisiología , Potenciales Evocados Motores/fisiología , Adulto Joven , Región Lumbosacra/fisiología , Músculo Esquelético/fisiología , Electromiografía , Vértebras Cervicales/fisiología , Vías Nerviosas/fisiologíaRESUMEN
OBJECTIVE: To compare whole-body kinematics, leg muscle activity, and discomfort while performing a 10-min carrying task with and without a passive upper-body exoskeleton (CarrySuitâ), for both males and females. BACKGROUND: Diverse commercial passive exoskeletons have appeared on the market claiming to assist lifting or carrying task. However, evidence of their impact on kinematics, muscle activity, and discomfort while performing these tasks are necessary to determine their benefits and/or limitations. METHOD: Sixteen females and fourteen males carried a 15kg load with and without a passive exoskeleton during 10-min over a round trip route, in two non-consecutive days. Whole-body kinematics and leg muscle activity were evaluated for each condition. In addition, leg discomfort ratings were quantified before and immediately after the task. RESULTS: The gastrocnemius and vastus lateralis muscle activity remained constant over the task with the exoskeleton. Without the exoskeleton a small decrease of gastrocnemius median activation was observed regardless of sex, and a small increase in static vastus lateralis activation was observed only for females. Several differences in sagittal, frontal, and transverse movements' ranges of motion were found between conditions and over the task. With the exoskeleton, ROM in the sagittal plane increased over time for the right ankle and pelvis for both sexes, and knees for males only. Thorax ROMs in the three planes were higher for females only when using the exoskeleton. Leg discomfort was lower with the exoskeleton than without. CONCLUSION: The results revealed a positive impact on range of motion, leg muscle activity, and discomfort of the tested exoskeleton.
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Dispositivo Exoesqueleto , Pierna , Músculo Esquelético , Humanos , Masculino , Femenino , Fenómenos Biomecánicos , Adulto , Músculo Esquelético/fisiología , Pierna/fisiología , Adulto Joven , Rango del Movimiento Articular/fisiología , Electromiografía , Soporte de Peso/fisiologíaRESUMEN
Previous research has demonstrated that oral contraceptive (OC) users have enhanced cardiorespiratory responses to arm metaboreflex activation (i.e., postexercise circulatory occlusion, PECO) and attenuated pressor responses to leg passive movement (PM) compared to non-OC users (NOC). We investigated the cardiorespiratory responses to arm or leg metaboreflex and mechanoreflex activation in 32 women (OC, n = 16; NOC, n = 16) performing four trials: 40% handgrip or 80% plantarflexion followed by PECO and arm or leg PM. OC and NOC increased mean arterial pressure (MAP) similarly during handgrip, plantarflexion and arm/leg PECO compared to baseline. Despite increased ventilation (VE) during exercise, none of the women exhibited higher VE during arm or leg PECO. OC and NOC similarly increased MAP and VE during arm or leg PM compared to baseline. Therefore, OC and NOC were similar across pressor and ventilatory responses to arm or leg metaboreflex and mechanoreflex activation. However, some differences due to OC may have been masked by disparities in muscle strength. Since women increase VE during exercise, we suggest that while women do not display a ventilatory response to metaboreflex activation (perhaps due to not reaching a theoretical metabolite threshold to stimulate VE), the mechanoreflex may drive VE during exercise in women.
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Anticonceptivos Orales , Ejercicio Físico , Reflejo , Humanos , Femenino , Ejercicio Físico/fisiología , Adulto , Anticonceptivos Orales/farmacología , Fuerza de la Mano , Pierna/fisiología , Presión Sanguínea/fisiología , Brazo/fisiología , Adulto JovenRESUMEN
Similar to nonamputees, female athletes with unilateral transtibial amputation (TTA) using running-specific leg prostheses (RSPs) may have worse running economy and higher rates of running-related injury than male athletes. Optimizing RSP configuration for female athletes could improve running economy and minimize biomechanical asymmetry, which has been associated with running-related injury. Nine females with a TTA ran at 2.5 m/s while we measured metabolic rates and ground reaction forces. Subjects used an RSP with a manufacturer-recommended stiffness category, one category less stiff and two categories less stiff than recommended. Use of an RSP two categories less stiff resulted in 3.0% lower net metabolic power (P = 0.04), 7.8% lower affected leg stiffness (P = 6.01 × 10-4), increased contact time asymmetry (P = 0.04), and decreased stance average vertical ground reaction force asymmetry (P = 0.04) compared with a recommended stiffness category RSP. Lower RSP stiffness (kN/m) values were associated with lower net metabolic power (P = 0.02), lower affected leg stiffness (P = 1.36 × 10-4), longer affected leg contact time (P = 1.46 × 10-4), and similar affected leg peak and stance-average vertical ground reaction force compared with higher RSP stiffness values. Subjects then used the RSP stiffness category that elicited the lowest net metabolic power with 100 g, 200 g, and 300 g added distally. We found no significant effects of added mass on net metabolic power, biomechanics, or asymmetry. These results suggest that female runners with a TTA could decrease metabolic power during running while minimizing biomechanical asymmetries, which have been associated with running-related injury, by using an RSP two categories less stiff than manufacturer recommended.NEW & NOTEWORTHY Females with unilateral transtibial amputation can improve running performance through reductions in net metabolic power by using a running-specific prosthesis (RSP) that is less stiff than manufacturer-recommended. Lower RSP stiffness values are associated with greater leg stiffness and contact time asymmetry, and lower stance-average vertical ground reaction force asymmetry. However, we found that adding mass to the RSP did not affect net metabolic power and stance-phase biomechanical asymmetries during running.
Asunto(s)
Amputación Quirúrgica , Miembros Artificiales , Pierna , Carrera , Humanos , Femenino , Carrera/fisiología , Adulto , Fenómenos Biomecánicos/fisiología , Pierna/fisiología , Amputados , Adulto Joven , Diseño de Prótesis , Atletas , Persona de Mediana Edad , Metabolismo Energético/fisiologíaRESUMEN
Lateral ankle sprains (LAS) often lead to chronic ankle instability (CAI). The Ebbets foot drills were created to strengthen the lower leg muscles and reduce the risk of LAS. The current study aimed to explore the activation of the lower leg muscles during the Ebbets foot drills. Twenty-two (22) college students without LAS participated in the study. Surface electromyography (sEMG) of the tibialis anterior (TA), tibialis posterior (TP), and peroneus longus (PL) was collected during each of the Ebbets foot drills and a normal walking trial. The sEMG mean root mean square (RMS) was calculated for each walking and Ebbets foot drill trial duration. The mean RMS was higher during the Ebbets foot drills compared to normal walking for all muscles. The TA sEMG mean RMS was greater (4.0-68.3%, P = 0.001-0.023) during all the Ebbets foot drills than during the walking trial. The TP had greater mean RMS during the toe-in (50.4%, P < 0.001), toe-out (55.0%, P < 0.001), and backward walking (47.3%, P < 0.001) drills, than during the walking trial. The PL had greater mean RMS during all Ebbets foot drills (19.4-53.7%, P < 0.001) except for the heel walking and inversion drills. Ebbets foot drills higher muscle activity than regular walking, suggesting that the Ebbets foot drills could aid in the strengthening of the TA, TP, and PL muscles. These results build evidence on Ebbets' theory and indicate that these drills may be used to rehabilitate LAS and CAI.
Asunto(s)
Electromiografía , Músculo Esquelético , Caminata , Humanos , Masculino , Músculo Esquelético/fisiología , Femenino , Adulto Joven , Caminata/fisiología , Traumatismos del Tobillo , Adulto , Pierna/fisiología , Terapia por Ejercicio/métodos , Inestabilidad de la Articulación/fisiopatología , Inestabilidad de la Articulación/rehabilitaciónRESUMEN
The Orthelligent Pro sensor is a practicable, portable measuring instrument. This study assessed the validity and reliability of this sensor in measuring single-leg countermovement jumps. Fifty healthy athletic adults participated in two measurement sessions a week apart in time. They performed single-leg countermovement jumps on the force plate while wearing the Orthelligent Pro sensor on their lower leg. During the first measurement session, Tester 1 invited the participants to make three single-leg countermovement jumps; subsequently, Tester 2 did the same. For assessing the sensor's intratester reliability, Tester 1 again invited the participants to make three single-leg countermovement jumps during the second measurement session. The sensor's validity was assessed by using the force plate results as the gold standard. To determinate the agreement between two measurements, Bland-Altman plots were created. The intertester reliability (ICC = 0.99; 0.97) and intratester reliability (ICC = 0.96; 0.82) were both excellent. The validity calculated (i) on the basis of the mean value of three jumps and (ii) on the basis of the maximum value of three jumps was very high, but it showed a systematic error. Taking this error into account, physiotherapists can use the Orthelligent Pro sensor as a valid and reliable instrument for measuring the jump height of countermovement jumps.