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1.
Scand J Med Sci Sports ; 34(2): e14585, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38356438

RESUMO

Ankle inversion orientation and peroneal activation insufficiency may contribute to lateral ankle sprains during landing in chronic ankle instability (CAI); however, how anticipation alters these factors is neglected. This study aimed to assess the impact of anticipation on joint orientation and muscle activity during landing in individuals with CAI. Fifteen participants with CAI and 15 healthy participants (control) were recruited to perform single-leg landings after bilateral countermovement jumps when the landing limb was specified before (planned) or after (unplanned) take-off. Joint angle (hip, knee, and ankle) and electromyography (gluteus medius, rectus femoris, biceps femoris, gastrocnemius lateral head, tibialis anterior, and peroneal longus) were collected and analyzed with 2 (groups) × 2 (conditions) statistical parametric mapping ANOVA. In the unplanned condition, the CAI group demonstrated a less plantarflexed (maximum difference [MD] = 9.5°, p = 0.047) and more inverted ankle joint (MD = 4.1°, p < 0.001) before ground contact, along with lower peroneal activity at ground contact compared to the control group (MD = 28.9% of peak activation, p < 0.001). No significant differences between groups were observed in the planned condition. In conclusion, anticipation may mask jump landing deficits in people with CAI, including inverted ankle orientation and reduced peroneus longus activity pre- and post-landing, which were observed exclusively in unplanned landings. Clinicians and researchers need to recognize the impact of anticipation on apparent landing deficits and consider the implications for injury prevention and rehabilitation strategies.


Assuntos
Tornozelo , Instabilidade Articular , Humanos , Articulação do Tornozelo/fisiologia , Perna (Membro)/fisiologia , Máscaras , Extremidade Inferior/fisiologia , Músculo Esquelético/fisiologia , Eletromiografia , Fenômenos Biomecânicos
2.
Biomed Eng Online ; 23(1): 6, 2024 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-38229090

RESUMO

BACKGROUND: Cycling workload is an essential factor in practical cycling training. Saddle height is the most studied topic in bike fitting, but the results are controversial. This study aims to investigate the effects of workload and saddle height on the activation level and coordination of the lower limb muscles during cycling. METHODS: Eighteen healthy male participants with recreational cycling experience performed 15 × 2-min constant cadence cycling at five saddle heights of 95%, 97%, 100%, 103%, and 105% of greater trochanter height (GTH) and three cycling workloads of 25%, 50%, and 75% of functional threshold power (FTP). The EMG signals of the rectus femoris (RF), tibialis anterior (TA), biceps femoris (BF), and medial gastrocnemius (MG) of the right lower limb were collected throughout the experiment. RESULTS: Greater muscle activation was observed for the RF and BF at a higher cycling workload, whereas no differences were observed for the TA and MG. The MG showed intensified muscle activation as the saddle height increased. The mean and maximum amplitudes of the EMG signals of the MG increased by 56.24% and 57.24% at the 25% FTP workload, 102.71% and 126.95% at the 50% FTP workload, and 84.27% and 53.81% at the 75% FTP workload, respectively, when the saddle height increased from 95 to 100% of the GTH. The muscle activation level of the RF was minimal at 100% GTH saddle height. The onset and offset timing revealed few significant differences across cycling conditions. CONCLUSIONS: Muscle activation of the RF and BF was affected by cycling workload, while that of the MG was affected by saddle height. The 100% GTH is probably the appropriate saddle height for most cyclists. There was little statistical difference in muscle activation duration, which might be related to the small workload.


Assuntos
Ciclismo , Carga de Trabalho , Humanos , Masculino , Ciclismo/fisiologia , Eletromiografia , Fenômenos Biomecânicos , Extremidade Inferior/fisiologia , Músculo Esquelético/fisiologia
3.
Sci Rep ; 14(1): 1813, 2024 01 20.
Artigo em Inglês | MEDLINE | ID: mdl-38245640

RESUMO

The biomechanical characteristics of runs in firefighters with different rescue tasks are unclear. This study aimed to explore the biomechanical characteristics of firefighters running in different rescue tasks and provide theoretical and practical references for firefighter training and occupational injury prevention. Eighteen professional healthy male firefighters were randomly selected as participants and tested running on different rescue tasks: wearing firefighting protective clothing (FPC), FPC+carrying a gas can (20 kg, FPC+ C), and FPC+carrying a mannequin (60 kg, FPC+M). Eight Qualisys infrared cameras and an AMTI 3D force measurement platform were used for the participant's acquisition of lower limb kinematic/kinetic data. The results showed that gait velocity and stride length of the FPC+GC and FPC+ M rescue tasks were significantly decreased compared to the FPC rescue task, while the support time was significantly increased. Compared to the FPC rescue task, the FPC+GC rescue task showed significant decreases in vertical ground reaction force (vGRF), minimum ankle dorsiflexion angle, and the maximum ankle plantarflexion power. In contrast, the FPC+M rescue task demonstrated significant increases in ankle range of motion, maximum hip extension angle, minimum knee flexion angle, maximum ankle dorsiflexion angle, maximum hip extension moment, maximum knee flexion moment, maximum hip flexion power, and hip and knee stiffness while exhibiting significant decreases in minimum ankle dorsiflexion angle. Compared to the FPC+ GC rescue task, the FPC+M rescue task exhibited significant increases in the maximum hip extension angle, minimum knee flexion angle, maximum ankle dorsiflexion angle, maximum hip flexion moment, maximum hip extension moment, maximum knee flexion moment, maximum ankle plantarflexion moment, maximum hip flexion power, maximum ankle dorsiflexion power, hip stiffness, and vGRF. Conversely, it showed significant decreases in the maximum knee flexion power. In conclusion, compared to the FPC rescue task, the FPC+GC and FPC+M rescue tasks altered the firefighter's gait performance, as evidenced by decreased gait velocity and stride length and increased support time. FPC+M rescue task would increase firefighter's risk of hip and knee injuries. Therefore, we suggest firefighters increase their strength training of the trunk, hip, and knee joint muscles as part of their daily training programs under large weight load status (60 kg and above) to reduce injury risk during rescue tasks.


Assuntos
Bombeiros , Corrida , Humanos , Masculino , Tornozelo , Articulação do Tornozelo/fisiologia , Extremidade Inferior/fisiologia , Articulação do Joelho/fisiologia , Marcha/fisiologia , Fenômenos Biomecânicos , Amplitude de Movimento Articular/fisiologia
4.
Artigo em Inglês | MEDLINE | ID: mdl-38163311

RESUMO

This study presents the biomimetic design of the structure and controller of AutoLEE-II, a self-balancing exoskeleton developed to assist patients in performing multiple rehabilitation movements without crutches or other supporting equipment. Its structural design is founded upon the human body structure, with an eliminated axis deviation and a raised CoM of the exoskeleton. The controller is a physical parameter-independent controller based on the CoM modification. Thus, the exoskeleton can adapt to patients with different physical parameters. Five subjects underwent exoskeleton-assisted rehabilitation training experiments, including squatting, tilting, and walking trainings. The results showed that the exoskeleton can assist patients in completing various rehabilitation exercises and help them maintain their balance during the rehabilitation training. This helpful role of the exoskeleton in rehabilitation training is analyzed through an electromyography (EMG) data analysis. The findings revealed that wearing the exoskeleton can reduce the activity of the lower limb muscles by approximately 20-30% when performing the same rehabilitation exercises.


Assuntos
Exoesqueleto Energizado , Robótica , Humanos , Robótica/métodos , Caminhada/fisiologia , Extremidade Inferior/fisiologia , Terapia por Exercício
5.
Sci Rep ; 14(1): 64, 2024 01 02.
Artigo em Inglês | MEDLINE | ID: mdl-38168920

RESUMO

Falls are caused by a combination of factors, including loss of lower limb muscle strength (LMS), and associated with declined performance status (PS). Age-related sarcopenia is generally associated with decreased muscle mass and strength of lower limb muscle but without a noticeable loss of those of upper limb or trunk muscle. However, no reports have focused on falls or LMS in chronic liver disease (CLD) patients. This study is the first to analyze the risk factors for falls in patients with CLD, focusing on LMS measurement using the Locomoscan. This study enrolled 315 CLD patients whose LMS was measured. The patients who experienced falls more than 1 year ago or during the observation period were classified as those who experienced falls. We found that risk factors for falls were PS1/2 and decreased LMS (< 0.32 N/kg). The group with sarcopenia had a higher frequency of decreased LMS (54 vs. 26%, p = 0.001) and falls (24 vs. 4.4%, p < 0.001) compared to the non-sarcopenia group. This study found that decreased LMS was an independent risk factor for falls. Assessment of LMS may be used as a better marker associated with the risk of falls in patients with CLD.


Assuntos
Hepatopatias , Sarcopenia , Humanos , Sarcopenia/diagnóstico , Força Muscular/fisiologia , Músculo Esquelético , Acidentes por Quedas , Hepatopatias/complicações , Extremidade Inferior/fisiologia , Força da Mão/fisiologia
6.
Gait Posture ; 108: 313-319, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38199090

RESUMO

BACKGROUND: Balance perturbation studies during walking have improved our understanding of balance control in various destabilizing conditions. However, it is unknown to what extent balance recovery strategies can be generalized across different types of mediolateral balance perturbations. RESEARCH QUESTION: Do similar mediolateral perturbations (foot placement versus surface translation) have similar effects on balance control and corresponding balance response strategies? METHODS: Kinetic and kinematic data were previously collected during two separate studies, each with 15 young, healthy participants walking on an instrumented treadmill. In both studies, medial and lateral balance perturbations were applied at 80% of the gait cycle either by a treadmill surface translation or a pneumatic force applied to the swing foot. Differences in balance control (frontal plane whole body angular momentum) and balance response strategies (hip abduction moment, ankle inversion moment, center of pressure excursion and frontal plane trunk moment) between perturbed and unperturbed gait cycles were evaluated using statistical parametric mapping. RESULTS: Balance disruptions after foot placement perturbations were larger and sustained longer compared to surface translations. Changes in joint moment responses were also larger for the foot placement perturbations compared to the surface translation perturbations. Lateral hip, ankle, and trunk strategies were used to maintain balance after medial foot placement perturbations, while a trunk strategy was primarily used after surface translations. SIGNIFICANCE: Surface and foot placement perturbations influence balance control and corresponding response strategies differently. These results can help inform the development of perturbation-based balance training interventions aimed at reducing fall risk in clinical populations.


Assuntos
Extremidade Inferior , Caminhada , Humanos , Caminhada/fisiologia , Extremidade Inferior/fisiologia , Pé/fisiologia , Marcha/fisiologia , Movimento (Física) , Fenômenos Biomecânicos , Equilíbrio Postural/fisiologia
7.
Clin Biomech (Bristol, Avon) ; 112: 106169, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38211422

RESUMO

BACKGROUND: Falls pose a significant health risk in older adults, with stair descent falls carrying particularly severe consequences. Reduced balance control and limb support due to aging-related physiological and neuromuscular decline are critical components in increased falling risk in older adults. Understanding the age-associated abnormalities in balance control and limb support strategies during sudden forward and downward body shift could reveal potential biomechanical deficits responsible for increased falling risks in older adults. This study investigates balance regulatory responses following first-time exposure to compelled forward and downward body shift in young and older adults. METHODS: Thirteen healthy old and thirteen healthy young adults participated in this study. Participants stood on two adjacent perturbation platforms in modified tandem stance. The leading limb support surface dropped 3 in. vertically at an unknown time. The anterior margin of stability and center of mass velocity, peak vertical ground reaction forces, and leading limb ankle and knee joint angular displacement, torque, and power during the initial response phase were compared between age groups. FINDINGS: Compared to young adults, older adults showed higher center of mass velocity, lower margin of stability, peak vertical ground reaction force, peak ankle and knee joint power, and peak knee joint torque during the initial response phase. INTERPRETATIONS: The abnormalities potentially identified in our study, particularly in dynamic stability regulation, limb support force generation, and shock absorption may affect the ability to arrest the body's forward and downward motion. These deficits may contribute to an increased risk of forward falls in aging.


Assuntos
Articulação do Joelho , Joelho , Humanos , Adulto Jovem , Idoso , Fenômenos Biomecânicos , Articulação do Joelho/fisiologia , Extremidade Inferior/fisiologia , Envelhecimento/fisiologia , Equilíbrio Postural/fisiologia
8.
J Biomech ; 162: 111891, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38147810

RESUMO

Differences in lower limb kinematics between males and females during functional activities may be attributed to sex differences in the incidence of patellofemoral pain, which is more common in females. To better comprehend the knee joint motion, it is necessary to understand both inter-segmental coordination patterns and angular amplitude. This exploratory study aimed to assess sex differences in pelvis-thigh and thigh-shank coordination patterns in the frontal and horizontal planes during walking. Data regarding the kinematic characteristics of the pelvis, thigh, and shank segments were collected from 26 males and 26 females performing walking at self-selected speeds using a 3D motion capture system. Furthermore, we compared the kinematics of the pelvis, thigh, and shank during walking as well as the pelvis-thigh and thigh-shank coordination patterns in the frontal and horizontal planes during the stance phase between males and females. Compared to males, females had greater thigh adduction (p < 0.001) and internal rotation (p < 0.001) throughout the stance phase; significantly greater frequency of the pelvis-thigh anti-phase pattern in the frontal plane in the early (p = 0.002) and mid-stance (p = 0.003); and significantly greater thigh-shank anti-phase pattern in the frontal plane in the early (p = 0.001) and mid-stance (p = 0.015). These results suggest the presence of sex differences in the inter-segmental coordination of the pelvis and lower limb during walking. However, as this study could not determine a causal relationship between female sex and knee joint injury, further longitudinal studies are needed to determine the effects of differences in coordination patterns on the pathophysiology of the injury and pain generation.


Assuntos
Traumatismos do Joelho , Coxa da Perna , Feminino , Humanos , Masculino , Caracteres Sexuais , Extremidade Inferior/fisiologia , Caminhada/fisiologia , Pelve , Fenômenos Biomecânicos , Marcha/fisiologia
9.
Physiol Behav ; 275: 114455, 2024 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-38161041

RESUMO

This study aimed to test the hypotheses that fatiguing unilateral handgrip contraction exhibits different changes in corticomotor excitability, which is evaluated by motor-evoked potentials (MEPs), in the lower limbs ipsilateral and contralateral to the fatigued hand, and that the changes in corticomotor excitability estimated by MEPs in the non-fatigued lower limbs affect the force exerted based on the sense of effort. Ten healthy males completed fatiguing unilateral handgrip contraction and force-matching tasks by static dorsiflexion before, immediately after, and 10 min after handgrip contraction. MEPs in the tibialis anterior (TA) were also measured before, immediately after, and 10 min after handgrip contraction. Fatiguing handgrip contractions resulted in asymmetrical MEPs in the TA muscles. Specifically, MEPs in the contralateral TA muscle were significantly increased (158 ± 60 %) and MEPs in the contralateral TA muscle were greater after the handgrip contraction than the ipsilateral MEPs (111 ± 30 %). Moreover, the torque exerted during the force-matching task significantly increased only in the contralateral ankle after the fatiguing handgrip contraction. Fatiguing unilateral handgrip contraction results in asymmetric changes in corticomotor excitability in the TA muscle, and the force exerted during the force-matching task based on the sense of effort becomes higher in the TA muscle with greater corticomotor excitability than that before fatiguing unilateral handgrip contraction.


Assuntos
Contração Muscular , Fadiga Muscular , Masculino , Humanos , Fadiga Muscular/fisiologia , Contração Muscular/fisiologia , Força da Mão/fisiologia , Extremidade Inferior/fisiologia , Músculo Esquelético/fisiologia , Potencial Evocado Motor/fisiologia , Eletromiografia , Estimulação Magnética Transcraniana/métodos
10.
Gait Posture ; 107: 306-311, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-37914560

RESUMO

BACKGROUND: Running on different surfaces, including natural and artificial surfaces, requires different gait mechanics, especially in individuals with foot deformity. RESEARCH QUESTION: How muscle activity change during running on the ground and artificial turf in males with pronated and supinated feet? METHODS: In this quasi-experimental study, we assessed a cohort of young male subjects, classified as healthy (n = 10), and with pronated (n = 10) or supinated (n = 10) feet. An electromyographic system was used to record lower limb muscle activity while running on the ground and artificial turf at constant speed (3.2 m/s). RESULTS: Results demonstrated significant main effects of the "surface" factor for vastus medialis activity during the loading phase (p = 0.040, η2 =0.147). Paired comparison revealed significantly greater vastus medialis activity while running on artificial grass with respect to the ground. A significant effect of the "group" factor was found for medial gastrocnemius during loading phase (p = 0.020, η2 =0.250). Paired-wise comparison revealed significantly lower medial gastrocnemius activity in the pronated and supinated feet groups than in the healthy group. SIGNIFICANCE: The healthy group may possess better neuromuscular control, allowing them to effectively coordinate the activation of the medial gastrocnemius with other muscles involved in running. Based on these findings, running on artificial turf is useful when the runner would like to strengthen vastus medialis muscle. The runner should carefully choose the running surface according to his/her state and training session goal.


Assuntos
, Extremidade Inferior , Masculino , Humanos , Feminino , Pronação/fisiologia , Pé/fisiologia , Extremidade Inferior/fisiologia , Músculo Esquelético/fisiologia , Marcha/fisiologia , Eletromiografia , Fenômenos Biomecânicos
11.
J Neuroeng Rehabil ; 20(1): 170, 2023 12 20.
Artigo em Inglês | MEDLINE | ID: mdl-38124144

RESUMO

BACKGROUND: There is currently no objective and accurate clinical assessment of reticular neuromuscular control in healthy subjects or patients with upper motor neuron injury. As a result, clinical dysfunctions of neuromuscular control could just be semi-quantified, efficacies and mechanisms of various therapies for neuromuscular control improving are difficult to verify. METHODS: Fourteen healthy participants were required to maintain standing balance in the kinetostatics model of Gusu Constraint Standing Training (GCST). A backward and upward constraint force was applied to their trunk at 0°, 20° and 25°, respectively. The multiplex recurrence network (MRN) was applied to analyze the surface electromyography signals of 16 muscles of bilateral lower limbs during the tests. Different levels of MRN network indices were utilized to assess reticular neuromuscular control. RESULTS: Compared with the 0° test, the MRN indices related to muscle coordination of bilateral lower limbs, of unilateral lower limb and of inter limbs showed significant increase when participants stood in 20° and 25° tests (P < 0.05). The indices related to muscle contribution of gluteal, anterior thigh and calf muscles significantly increased when participants stood in 20° and 25° tests (P < 0.05). CONCLUSIONS: This study applied the dynamical network indices of MRN to analyze the changes of neuromuscular control of lower limbs of healthy participants in the kinetostatics model of GCST. Results showed that the overall coordination of lower limb muscles would be significantly enhanced during performing GCST, partly by the enhancement of neuromuscular control of single lower limb, and partly by the enhancement of joint control across lower limbs. In particular, the muscles in buttocks, anterior thighs and calves played a more important role in the overall coordination, and their involvement was significantly increased. The MRN could provide details of control at the bilateral lower limbs, unilateral lower limb, inter limbs, and single muscle levels, and has the potential to be a new tool for assessing the reticular neuromuscular control. Trial registration ChiCTR2100055090.


Assuntos
Relevância Clínica , Músculo Esquelético , Humanos , Eletromiografia , Músculo Esquelético/fisiologia , Extremidade Inferior/fisiologia , Perna (Membro)
12.
IEEE Int Conf Rehabil Robot ; 2023: 1-6, 2023 09.
Artigo em Inglês | MEDLINE | ID: mdl-37941174

RESUMO

The clinical usage of powered exoskeletons for the rehabilitation of patients affected by lower limb disorders has been constantly growing in the last decade. This paper presents a versatile and reliable gait pattern generator for these devices able to accommodate several gait requirements, i.e., step length, clearance, and time, and to suit a wide range of persons. In the proposed method, the human gait phases have been modeled with a set of trajectories as Bèzier curves, enabling a robotic lower-limb exoskeleton to walk in a continuous way, similarly to the physiological gait cycle. The kinematic, kinetic, and spatial requirements for each gait phase are translated into the control points of the Bèzier curves that define the trajectory for that phase. The outcome of this study has been tested on real scenarios with a group of healthy subjects wearing the TWIN lower-limb exoskeleton. They were asked to walk at different speeds, generally defined as slow, medium, and fast. The results are shown in terms of joint positions, velocities, and body-mass-normalized torques. The maximum hip and knee joint torque was observed in the support phase. While, at higher speeds the maximum hip torque was provided in the swing phase due to the mechanical properties and limits of the device. In terms of speed, all the subjects reached 0.44 m/s, which is the minimum required community ambulation.


Assuntos
Exoesqueleto Energizado , Humanos , Marcha/fisiologia , Caminhada/fisiologia , Extremidade Inferior/fisiologia , Articulação do Joelho/fisiologia , Fenômenos Biomecânicos
13.
Sensors (Basel) ; 23(21)2023 Oct 24.
Artigo em Inglês | MEDLINE | ID: mdl-37960383

RESUMO

BACKGROUND: This systematic review aimed to provide a comprehensive overview of the effects of functional electrical stimulation (FES) on gait characteristics in healthy individuals. METHODS: Six electronic databases (PubMed, Embase, Epistemonikos, PEDro, COCHRANE Library, and Scopus) were searched for studies evaluating the effects of FES on spatiotemporal, kinematic, and kinetic gait parameters in healthy individuals. Two examiners evaluated the eligibility and quality of the included studies using the PEDro scale. RESULTS: A total of 15 studies met the inclusion criteria. The findings from the literature reveal that FES can be used to modify lower-limb joint kinematics, i.e., to increase or reduce the range of motion of the hip, knee, and ankle joints. In addition, FES can be used to alter kinetics parameters, including ground reaction forces, center of pressure trajectory, or knee joint reaction force. As a consequence of these kinetics and kinematics changes, FES can lead to changes in spatiotemporal gait parameters, such as gait speed, step cadence, and stance duration. CONCLUSIONS: The findings of this review improve our understanding of the effects of FES on gait biomechanics in healthy individuals and highlight the potential of this technology as a training or assistive solution for improving gait performance in this population.


Assuntos
Marcha , Caminhada , Humanos , Caminhada/fisiologia , Marcha/fisiologia , Articulação do Joelho/fisiologia , Joelho , Extremidade Inferior/fisiologia , Fenômenos Biomecânicos
14.
Sensors (Basel) ; 23(21)2023 Oct 31.
Artigo em Inglês | MEDLINE | ID: mdl-37960541

RESUMO

To maintain a healthy lifestyle, adults rely on their ability to walk while simultaneously managing multiple tasks that challenge their coordination. This study investigates the impact of cognitive dual tasks on lower-limb muscle activities in 21 healthy young adults during both gait initiation and steady-state gait. We utilized wireless electromyography sensors to measure muscle activities, along with a 3D motion capture system and force plates to detect the phases of gait initiation and steady-state gait. The participants were asked to walk at their self-selected pace, and we compared single-task and dual-task conditions. We analyzed mean muscle activation and coactivation in the biceps femoris, vastus lateralis, gastrocnemius, and tibialis anterior muscles. The findings revealed that, during gait initiation with the dual-task condition, there was a decrease in mean muscle activation and an increase in mean muscle coactivation between the swing and stance limbs compared with the single-task condition. In steady-state gait, there was also a decrease in mean muscle activation in the dual-task condition compared with the single-task condition. When participants performed dual-task activities during gait initiation, early indicators of reduced balance capability were observed. Additionally, during dual-task steady-state gait, the knee stabilizer muscles exhibited signs of altered activation, contributing to balance instability.


Assuntos
Marcha , Extremidade Inferior , Adulto Jovem , Humanos , Eletromiografia , Extremidade Inferior/fisiologia , Marcha/fisiologia , Músculo Esquelético/fisiologia , Caminhada/fisiologia
15.
Sensors (Basel) ; 23(21)2023 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-37960596

RESUMO

In this study, to establish the biomechanical characteristics of commercial vehicle drivers' muscles and bones while operating the three pedals, a driver pedal-operation simulator was built, and the real-life situation was reconstructed in OpenSim 3.3 software. We set up three seat heights to investigate the drivers' lower limbs, and the research proceeded in two parts: experiment and simulation. Chinese adult males in the 95th percentile were selected as the research participants. In the experiment, Delsys wireless surface electromyography (EMG) sensors were used to collect the EMG signals of the four main muscle groups of the lower limbs when the drivers operated the three pedals. Then, we analyzed the muscle activation and the degree of muscle fatigue. The simulation was based on OpenSim software to analyze the driver's lower limb joint angles and joint torque. The results show that the activation of the hamstrings, gastrocnemius, and rectus femoris muscles were higher in the four muscle groups. In respect of torque, in most cases, hip joint torque > knee joint torque > ankle joint torque. The knee joint angles were the largest, and the ankle joint angles changed the most. The experimental results provide a reference for improving drivers' handling comfort in commercial vehicles and provide theoretical bases for cab design and layout optimization.


Assuntos
Extremidade Inferior , Músculo Esquelético , Masculino , Adulto , Humanos , Fenômenos Biomecânicos , Extremidade Inferior/fisiologia , Músculo Esquelético/fisiologia , Articulação do Joelho/fisiologia , Eletromiografia , Torque
16.
J Bodyw Mov Ther ; 36: 30-37, 2023 10.
Artigo em Inglês | MEDLINE | ID: mdl-37949575

RESUMO

OBJECTIVE: To identify the effects of instrument-assisted soft tissue mobilization (IASTM) and foam roller self-myofascial release (FRSMR) strategies and verify their results in athletic performance. METHOD: Systematic review conducted in four databases from 2017. The inclusion criteria were randomized controlled trials assessing the effects of two forms of soft tissue mobilization on athletes' performance. The risk of bias was analyzed using the Cochrane Handbook scale. RESULTS: Ten studies were included for qualitative analysis. IASTM increased range of motion, knee joint kinetic force, peak torque, and angular velocity in dorsiflexion and plantar flexion. The technique increases isometric strength and isokinetic power in vertical jumping. FRSMR was relevant in counter movement jumping between the pre- and post-intervention conditions, mainly by increasing strength in the initial jumping phase. CONCLUSIONS: IASTM should be used in sports preparation to improve muscle response and explosive force production. FRSMR increases flexibility as it tends to restore tissue elasticity, but it does not improve aerobic activity. The suggested time for strategy intervention is at least 90 s per muscle group.


Assuntos
Desempenho Atlético , Terapia de Liberação Miofascial , Humanos , Extremidade Inferior/fisiologia , Joelho , Desempenho Atlético/fisiologia , Articulação do Joelho/fisiologia , Amplitude de Movimento Articular/fisiologia
17.
PLoS One ; 18(11): e0294161, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37972031

RESUMO

To enhance human mobility, training interventions and assistive lower limb wearable robotic designs must draw insights from movement tasks from daily life. This study aimed to analyze joint peak power, limb and joint work, and muscle activity of the lower limb during a series of stair ambulation conditions. We recruited 12 subjects (25.4±4.5 yrs, 180.1±4.6 cm, 74.6±7.9 kg) and studied steady gait and gait transitions between level walking, stair ascent and stair descent for three staircase inclinations (low 19°, normal 30.4°, high 39.6°). Our analysis revealed that joint peak power, limb and joint work, and muscle activity increased significantly compared to level walking and with increasing stair inclination for most of the conditions analyzed. Transition strides had no increased requirements compared to the maxima found for steady level walking and steady stair ambulation. Stair ascent required increased lower limb joint positive peak power and work, while stair descent required increased lower limb joint negative peak power and work compared to level walking. The most challenging condition was high stair inclination, which required approximately thirteen times the total lower limb joint positive and negative net work during ascent and descent, respectively. These findings suggest that training interventions and lower limb wearable robotic designs must consider the major increases in lower limb joint and muscle effort during stair ambulation, with specific attention to the demands of ascent and descent, to effectively improve human mobility.


Assuntos
Marcha , Caminhada , Humanos , Fenômenos Biomecânicos/fisiologia , Caminhada/fisiologia , Marcha/fisiologia , Extremidade Inferior/fisiologia , Músculos/fisiologia , Articulação do Joelho/fisiologia
18.
PLoS One ; 18(11): e0289089, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-38011209

RESUMO

This study was aimed to analyze in detail how the fatigue effects to kinematic parameters of body weight squat exercise (BSQ) by dividing a squat cycle into four different regions. Twenty-one male athletes participated in this study. Participants were divided into two groups according to their lower limb muscle ratio (LLMR). The BSQ was performed until participants were unable to continue the exercise due to the fatigue. Linear and angular kinematics were obtained by motion analysis software which has high validity and reliability. There was no significant but had large effect size interaction between fatigue conditions and LLMR groups in terms of knee ROM in the extension phase and hip angular velocity in braking phase of the flexion (0.08 > p >0.05, 0.18 > [Formula: see text] > 0.16). Fatigue condition did not have a significant effect on the duration in the acceleration and braking phases of BSQ (p > 0.05). There were many significant main effects on kinematics in the different regions due to the fatigue (0.01 < p <0.05, 0.44 > [Formula: see text] > 0.14). In the fatigue condition, there was a polynomial relationship between velocity of shoulder and hip joints (R2flex = 0.82, R2ext = 0.72) rather than linear (R2flex = 0.64, R2ext = 0.53) and coefficient correlations also decreased (rflex = 0.88 to 0.80, rext = 0.92 to 0.73). The sticking region was observed in the non-fatigue condition and disappeared when fatigue occurred. These results suggest that LLMR may be taken into consideration in the squat exercises, joint tracking may vary for velocity-based squat training and pre-test for sticking region observation may be apply with the BSQ.


Assuntos
Articulação do Joelho , Joelho , Humanos , Masculino , Fenômenos Biomecânicos , Reprodutibilidade dos Testes , Joelho/fisiologia , Articulação do Joelho/fisiologia , Extremidade Inferior/fisiologia , Amplitude de Movimento Articular/fisiologia
19.
PLoS One ; 18(10): e0292999, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37831688

RESUMO

PURPOSE: Evidence directly comparing the effects of bilateral and unilateral conditioning activities is limited. Therefore, the aim of this study was to assess the acute effect of unilateral and bilateral conditioning activity on vastus lateralis stiffness, countermovement jump parameters, and 10 m sprint. METHODS: Twelve semi-professional basketball players participated in this study (age: 23 ± 4 yrs; body mass: 84.7 ± 10.6 kg; body height: 192 ± 6 cm; basketball training experience: 11 ± 4 yrs) performed four experimental sessions to compare the acute effects of bilateral, stronger-only, weaker-only lower limb or no conditioning activity on vastus lateralis stiffness, countermovement jumps variables (height; peak velocity; peak force, contraction time, countermovement depth, and modified reactive strength index and 10 m sprint time. Measurements were performed 5 minutes before and in the 5th and 10th minutes after CA. RESULTS: Bilateral conditioning activity significantly increase the countermovement jump height (p = 0.002; ES = 0.71) and the reactive strength index modified (p = 0.010; ES = 0.59). Moreover, a significantly higher peak force in the stronger than in the weaker limb was found (p<0.001) without any differences between conditions and time points (p>0.05). However, there were no significant (p>0.05) interactions and effects of conditions or time-point in the case of the other countermovement jump variables, vastus lateralis stiffness, and 10m sprint time. CONCLUSION: Unilateral and bilateral drop jumps (3 sets of 5 repetitions) did not affect the vastus lateralis stiffness and time of the 10m sprint. However, only bilateral drop jumps effectively enhanced the countermovement jump height and modified reactive strength index. Bilateral drop jumps might be a useful part of a warm-up to improve jumping performance in basketball players.


Assuntos
Desempenho Atlético , Basquetebol , Exercício de Aquecimento , Humanos , Adulto Jovem , Adulto , Estudos Cross-Over , Extremidade Inferior/fisiologia , Basquetebol/fisiologia , Músculo Quadríceps , Força Muscular/fisiologia , Desempenho Atlético/fisiologia
20.
J Vis Exp ; (199)2023 09 22.
Artigo em Inglês | MEDLINE | ID: mdl-37811948

RESUMO

Reestablishing balance after a trip is challenging for lower-limb amputees and often results in a fall. The effectiveness of reestablishing balance following a trip depends on factors such as amputation level (transtibial or transfemoral) or which limb is tripped (prosthetic or sound/lead or trailing). Understanding the recovery responses can help identify strategies to avoid a trip becoming a fall and what trip-response functionality could be designed into a prosthesis. This study presents an experimental approach for inducing unexpected trips in individuals with amputation. Tripping was manually triggered by activating an electromagnetic device to raisea polypropylene wire to obstruct (bring to a near halt) theswinging limb during its mid-swing phase. A safety harness attached to a ceiling rail ensured participants did not hit the ground if they failed to reestablish balance following the trip (i.e., it prevented a fall from occurring). One transtibial amputee completed repeated walking trials in which a trip was induced around 1 out of 15 times to avoid it being anticipated. 3D kinematics were determined via two smartphones (60Hz) using the OpenCap software, highlighting that the experimental approach induced meaningful tripping/recovery responses dependent on which limb was tripped (prosthetic or sound). The presented methodology avoids using a rigid obstacle, potentially reducing the risk of injuries, and is inexpensive and easy to set up. Importantly it permits a trip to be unexpectedly introduced during the mid-swing phase of the gait and hence provides an approach for identifying real-world trip recovery responses. When tripping the sound limb, participants could 'disentangle' from the trip-wire (post-trip) by plantarflexing the ankle, but such action was not possible when tripping the prosthetic limb.


Assuntos
Amputados , Membros Artificiais , Humanos , Extremidade Inferior/cirurgia , Extremidade Inferior/fisiologia , Marcha/fisiologia , Caminhada/fisiologia , Fenômenos Biomecânicos
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