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1.
J Bodyw Mov Ther ; 30: 154-159, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-35500964

RESUMO

OBJECTIVE: Police officers, particularly the ones who are trained to be on "special forces", perform a wide range of hazardous and physically demanding activities when aiming to protect and serve. The purpose of this study was to investigate the association between lower limb and trunk muscle endurance with drop vertical jump (DVJ) height in a special military police force. METHODS: One hundred and three male military men (age: 36 ± 5.0 years; height: 1.76 ± 0.05 m; weight: 81.8 ± 9.7 kg) volunteered to take part in this study. SIX TESTS WERE PERFORMED: DVJ, McGill core battery (trunk flexion, trunk extension, and side bridge test-right and left), and single-leg squat repetitions. Correlations were analyzed using the Pearson correlation coefficient (r). The level of significance for all analyses was set at p ≤ 0.05. RESULTS: Single-leg squat repetitions were positively associated with DVJ height, contact time and flight time (p = 0.00093∗∗, p = 0.00085∗∗, and p = 0.00098∗∗ respectively). No correlation was observed between trunk muscle endurance and DVJ. CONCLUSION: Therefore, it was concluded that greater endurance of the lower limb muscles, as demonstrated by the single leg squat, was associated with better performance in a DVJ. Individuals should consider incorporating single leg squats into their fitness program to develop muscular endurance and possibly perform better in the DVJ.


Assuntos
Músculo Esquelético , Tronco , Adulto , Exercício Físico/fisiologia , Humanos , Extremidade Inferior/fisiologia , Masculino , Músculo Esquelético/fisiologia , Amplitude de Movimento Articular , Tronco/fisiologia
2.
J Bodyw Mov Ther ; 30: 60-68, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-35500980

RESUMO

BACKGROUND: Limited biomechanical data exist describing how yoga asanas (postures) load the limbs and joints, and little evidence-based recommendations for yoga injury prevention are available. This study aimed to establish joint loading metrics for an injury-prone, yet common yoga pose, the Triangle asana (Trikonasana) by identifying how stance width adjustments alter lower extremity loading. METHODS: Eighteen yoga practitioners underwent 3D motion analysis while performing Trikonasana with self-selected (SS) stance width and -30, -20, -10, +10, +20, and +30% of SS stance width. Ground reaction forces (GRFs), joint forces, and joint moments were calculated for the leading and trailing limb ankle, knee, and hip. One-way repeated-measures analysis of variance determined differences in loading due to stance width. RESULTS: GRFs, net joint forces, and net joint moments were significantly affected by stance width where increasing stance width increased leading limb loading but decreased trailing limb loading. CONCLUSIONS: Altering stance width of Trikonasana influences lower extremity limb loading, and these loading responses were limb-dependent. Yoga practitioners and instructors can use this information to objectively support increasing or decreasing stance width to reduce or increase limb loading according to their goals or to make accommodations to groups such as beginners or at-risk populations for safer, more accessible yoga practices. Cuing a wider or narrower stance width will not have the same effect on both limbs.


Assuntos
Ioga , Articulação do Tornozelo/fisiologia , Fenômenos Biomecânicos , Humanos , Articulação do Joelho/fisiologia , Extremidade Inferior/fisiologia
3.
Artigo em Inglês | MEDLINE | ID: mdl-35409940

RESUMO

OBJECTIVES: To investigate the biomechanics of Ukemi in relation to head and neck injury in adult judokas with varying skill sets. DESIGN: Narrative systematic review. METHODS: An extensive literature search was performed using PubMed, Google Scholar, Science direct and EMBASE from inception to April 2021. Studies were included if they: (1) reported biomechanical analysis of judo throws and Ukemi; (2) were on adult judoka populations; (3) discussed injury related to judo technique. The included studies were assessed for risk of bias using a five-part modified STROBE checklist. A narrative synthesis was performed due to the heterogeneity of included studies. RESULTS: 173 titles and abstracts were screened with 16 studies (158 judokas, 9 of which were female) included. All studies used 3D biomechanical analysis to assess Ukemi. Ukemi implementation produced reduced kinematic data in comparison to direct occipital contact, which was always below the injury threshold. Analysis of lower limb and trunk kinematics revealed variances in Ukemi between novice and experienced judoka. Whilst no significant differences were seen in neck flexion angles, hip, knee and trunk angle time plots revealed greater extension angles in experienced judokas. CONCLUSIONS: Ukemi is essential in preventing head and neck injuries; however, technique differs between experienced and novice judoka. Larger flexion angles of the hip, knee and trunk are seen in novice judoka, which correlate with increased kinematic data. The association of greater neck muscle strength with improved Ukemi is weak. However, a negative correlation was established between fatigue and breakfall skill by one study.


Assuntos
Artes Marciais , Fenômenos Biomecânicos/fisiologia , Feminino , Humanos , Extremidade Inferior/fisiologia , Artes Marciais/fisiologia , Força Muscular , Tronco/fisiologia
4.
Artigo em Inglês | MEDLINE | ID: mdl-35410001

RESUMO

(1) Background: The objective of this study was to determine physical and biomechanical changes in age groups upon running. (2) Method: 75 male adults (20-80s) participated in the study. Bone mineral density and lower extremity joint strength were measured according to age-increase targeting. Based on age, correlations among running characteristics, impulse, impact force, maximum vertical ground reaction force, loading rate, lower extremity joint 3D range of motion, joint moment, and power upon running motion were calculated. (3) Result: Older runners tended to show lower bone mineral density, extremity maximum strength, stride time, and stride distance, with smaller RoM and joint power of ankle and knee joints in the sagittal plane, compared with younger subjects. However, there were no significant correlations between age and impact variables (i.e., impulse, impact force, peak GRF, and loading rate) during running. (4) Conclusion: Older runners tend to show weaker physical strength characteristics, such as bone mineral density and muscle strength and lower joint functionality of ankle and knee joints during running, compared with younger runners. Therefore, strengthening the lower extremity muscle and improving dynamic joint function, especially for ankle joints, can be helpful for injury prevention during running.


Assuntos
Corrida , Adulto , Articulação do Tornozelo , Fenômenos Biomecânicos , Humanos , Extremidade Inferior/fisiologia , Masculino , Amplitude de Movimento Articular/fisiologia , Corrida/fisiologia
5.
Eur J Neurosci ; 55(7): 1810-1824, 2022 04.
Artigo em Inglês | MEDLINE | ID: mdl-35274383

RESUMO

Neural interactions between upper and lower limbs underlie motor coordination in humans. Specifically, upper limb voluntary muscle contraction can facilitate spinal and corticospinal excitability of the lower limb muscles. However, little remains known on the involvement of somatosensory information in arm-leg neural interactions. Here, we investigated effects of voluntary and electrically induced wrist flexion on corticospinal excitability and somatosensory information processing of the lower limbs. In Experiment 1, we measured transcranial magnetic stimulation (TMS)-evoked motor evoked potentials (MEPs) of the resting soleus (SOL) muscle at rest or during voluntary or neuromuscular electrical stimulation (NMES)-induced wrist flexion. The wrist flexion force was matched to 10% of the maximum voluntary contraction (MVC). We found that SOL MEPs were significantly increased during voluntary, but not NMES-induced, wrist flexion, compared to the rest (P < .001). In Experiment 2, we examined somatosensory evoked potentials (SEPs) following tibial nerve stimulation under the same conditions. The results showed that SEPs were unchanged during both voluntary and NMES-induced wrist flexion. In Experiment 3, we examined the modulation of SEPs during 10%, 20% and 30% MVC voluntary wrist flexion. During 30% MVC voluntary wrist flexion, P50-N70 SEP component was significantly attenuated compared to the rest (P = .003). Our results propose that the somatosensory information generated by NMES-induced upper limb muscle contractions may have a limited effect on corticospinal excitability and somatosensory information processing of the lower limbs. However, voluntary wrist flexion modulated corticospinal excitability and somatosensory information processing of the lower limbs via motor areas.


Assuntos
Potencial Evocado Motor , Contração Muscular , Estimulação Elétrica , Eletromiografia , Potencial Evocado Motor/fisiologia , Humanos , Extremidade Inferior/fisiologia , Contração Muscular/fisiologia , Músculo Esquelético/fisiologia , Tratos Piramidais/fisiologia , Estimulação Magnética Transcraniana , Extremidade Superior
6.
Sci Rep ; 12(1): 4509, 2022 03 16.
Artigo em Inglês | MEDLINE | ID: mdl-35296707

RESUMO

This study examines how people learn to perform lower limb control in a novel task with a hoverboard requiring to maintain dynamic balance. We designed an experiment to investigate the learning of hoverboard balance and two control strategies: A hip strategy, which mainly uses hip movements to change the angle of the foot, and an ankle strategy relying more on ankle motion to control the orientation of hoverboard plates controlling the motion. Motor learning was indicated by a significant [Formula: see text]% decrease in the trial completion time (p < 0.001) and a significant 24 ± 11% decrease in total muscle activation (p < 0.001). Furthermore, the participants, who had no prior experience riding a hoverboard, learned an ankle strategy to maintain their balance and control the hoverboard. This is supported by significantly stronger cross-correlation, phase synchrony, lower dynamic time warping distance between the hoverboard plate orientation controlling hoverboard motion, and the ankle angle when compared to the hip angle. The adopted ankle strategy was found to be robust to the foot orientation despite salient changes in muscle group activation patterns. Comparison with results of an experienced hoverboard rider confirmed that the first-time riders adopted an ankle strategy.


Assuntos
Tornozelo , Movimento , Tornozelo/fisiologia , Articulação do Tornozelo , Fenômenos Biomecânicos , , Humanos , Extremidade Inferior/fisiologia , Equilíbrio Postural/fisiologia
7.
Artigo em Inglês | MEDLINE | ID: mdl-35270589

RESUMO

Deficits in hamstring muscle strength and in hip range of motion (ROM) have been considered risk factors for hamstring muscle injuries. However, there is a lack of information on how chronic exposure to regular football training affects hamstring muscle strength and hip ROM. The aim of this study was to examine the longitudinal effect of football training and competition during a complete season on hamstring muscle strength and hip ROM in football players. A total of 26 semi-professional football players underwent measurements of isometric hamstring muscle strength and passive hip flexion/extension, and internal/external hip rotation (IR/ER) ROM during the football season (pre-season, mid-season, end-season). Compared to pre-season, hamstring muscle strength increased in the dominant (+11.1%, p = 0.002) and non-dominant (+10.5%, p = 0.014) limbs in the mid-season. Compared to mid-season, hamstring strength decreased in the dominant (-9.3%, p = 0.034) limb at end-season. Compared to the pre-season, hip extension ROM decreased in mid-season in the dominant (-31.7%, p = 0.007) and non-dominant (-44.1%, p = 0.004) limbs, and further decreased at end-season (-49.0%, p = 0.006 and -68.0%, p < 0.001) for the dominant and non-dominant limbs. Interlimb asymmetry for hip IR ROM increased by 57.8% (p < 0.002) from pre-season to mid-season. In summary, while hamstring muscle strength increased during the first half of the football season in football players, a progressive reduction in hip extension ROM was observed throughout the season. The reduced hip extension ROM suggests a reduced mobility of the hip flexors, e.g., iliopsoas, produced by the continuous practice of football. Consequently, hip-specific stretching and conditioning exercises programs should be implemented during the football season.


Assuntos
Futebol Americano , Músculos Isquiossurais , Tornozelo , Futebol Americano/lesões , Músculos Isquiossurais/fisiologia , Extremidade Inferior/fisiologia , Amplitude de Movimento Articular/fisiologia , Estações do Ano
8.
Sci Med Footb ; 6(1): 40-48, 2022 02.
Artigo em Inglês | MEDLINE | ID: mdl-35236218

RESUMO

Muscle activation has been studied in soccer players kicking stationary balls with the dominant foot. This study evaluated swinging and support limb muscle activation during the instep kick using different feet and ball approach conditions.Vastus medialis (VM), biceps femoris (BF), gastrocnemius medialis (GM) and tibialis anterior (TA) activations were evaluated during maximal instep kicks with both feet and the ball in five conditions (n = 18): stationary (STAT), approaching anteriorly (ANT), posteriorly (POST), laterally (LAT) and medially (MED). A repeated-measures two-way ANOVA compared activations between feet and ball conditions throughout the kicking (0-100%) and follow-through phases (101-200%). Close to ball contact (81-124%), non-dominant support GM had greater activation than the dominant one. The LAT and MED conditions differed within the cycle in the swinging VM (0-21%; 191-200%), BF (13-70%; 121-161%), GM (22-82%; 121-143%) and TA (0-32%; 55-97%; 186-200%) and in support VM (0-81%), BF (6-24%; 121-161%) and GM (24-87%). Players require greater support GM activation to stabilize the ankle during non-dominant kicks. Muscle activation differences between LAT and MED indicate that the kicking strategies are altered when kicking balls approaching from different directions.


Assuntos
Futebol , Fenômenos Biomecânicos , , Extremidade Inferior/fisiologia , Músculo Esquelético/fisiologia , Futebol/fisiologia
9.
Br J Sports Med ; 56(9): 490-498, 2022 May.
Artigo em Inglês | MEDLINE | ID: mdl-35135826

RESUMO

OBJECTIVES: Vertical jump performance (height) is a more representative metric for knee function than horizontal hop performance (distance) in healthy individuals. It is not known what the biomechanical status of athletes after anterior cruciate ligament (ACL) reconstruction (ACLR) is at the time they are cleared to return to sport (RTS) or whether vertical performance metrics better evaluate knee function. METHODS: Standard marker-based motion capture and electromyography (EMG) were collected from 26 male athletes cleared to RTS after ACLR and 22 control healthy subjects during single leg vertical jumps (SLJ) and single leg drop jumps (SLDJ). Performance outcomes, jump height and the Reactive Strength Index, were calculated. Sagittal plane kinematics, joint moments and joint work were obtained using inverse dynamics and lower limb muscle forces were computed using an EMG-constrained musculoskeletal model. Muscle contribution was calculated as a percentage of the impulse of all muscle forces in the model. Between-limb and between-group differences were explored using mixed models analyses. RESULTS: Jump performance, assessed by jump height and Reactive Strength Index, was significantly lower in the involved than the uninvolved limb and controls, with large effect sizes. For the ACLR group, jump height limb symmetry index was 83% and 77% during the SLJ and SLDJ, respectively. Work generation was significantly less in the involved knee compared to uninvolved limb and controls during the SLJ (p<0.001; d=1.19; p=0.003, d=0.91, respectively) and during the SLDJ (p<0.001; d=1.54; p=0.002, d=1.05, respectively). Hamstrings muscle contribution was greater in the involved compared to the uninvolved limb and controls, whereas soleus contribution was lower in the involved limb compared to controls. CONCLUSIONS: During vertical jumps, male athletes after ACLR at RTS still exhibit knee biomechanical deficits, despite symmetry in horizontal functional performance and strength tests. Vertical performance metrics like jump height and RSI can better identify interlimb asymmetries than the more commonly used hop distance and should be included in the testing battery for the RTS.


Assuntos
Lesões do Ligamento Cruzado Anterior , Reconstrução do Ligamento Cruzado Anterior , Lesões do Ligamento Cruzado Anterior/cirurgia , Atletas , Fenômenos Biomecânicos , Feminino , Humanos , Articulação do Joelho , Perna (Membro) , Extremidade Inferior/fisiologia , Masculino , Volta ao Esporte
10.
J Biomech Eng ; 144(8)2022 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-35171239

RESUMO

In this paper, a multibody model was developed in the framework of biotribology of lower limb artificial joints. The presented algorithm performs the inverse dynamics of musculoskeletal systems with the aim to achieve a tool for the calculation of the joint reaction forces. The revolute joint, the cam joint, the spherical joint and the free joint were considered in the analyzed lower limb system by introducing a novel analytical formulation of the rheonomic constraint equations based on the quaternions theory. Within the kinematical analysis, the curved muscle paths were modeled by simulating their geodesic wrapping over bony surfaces while the muscle actuations were formulated through the Hill muscle model. The developed theoretical model was developed in matlab environment allowing to follow the classical musculoskeletal analysis pipeline: kinematical analysis, inverse dynamics, and static optimization, applied to the lower limb during the gait kinematics. The validation of the results was obtained by comparing the calculated hip joint reactions with the ones obtained in vivo by Bergmann and calculated by Opensim software, showing a satisfactory agreement. The proposed model and algorithm represent a fully open and controllable synovial joint tribological configuration generator tool, useful to be coupled with numerical lubrication/contact models in the framework of the in silico artificial joints tribological optimization.


Assuntos
Marcha , Extremidade Inferior , Algoritmos , Fenômenos Biomecânicos , Marcha/fisiologia , Articulação do Quadril/fisiologia , Articulações/fisiologia , Extremidade Inferior/fisiologia , Modelos Biológicos , Músculo Esquelético/fisiologia
11.
Gait Posture ; 94: 15-18, 2022 05.
Artigo em Inglês | MEDLINE | ID: mdl-35193084

RESUMO

BACKGROUND: Bipedalism is a unique function in humans. Various investigations in bipedal walking have assessed the kinetic chain from the pelvis to the lower limbs. However, few studies have investigated the functions of the upper body including the psoas major muscles. In the present study, a bipedal-walking human full-body skeletal model, "the bipedal android model", was generated by attaching air cylinder devices to simulate the contraction and relaxation of various muscles required for bipedal walking, including the psoas major muscles. The bipedal-walking principle was discussed using the model. METHODS: Every part of a human full-body skeletal model was connected by wires or cables to retain the mobility of each joint. Then the psoas major (PM), gluteus minimus (GM), long head of biceps femoris (BF), quadriceps femoris (QF), and semimembranosus (SM) muscles were simulated in the skeletal model using air cylinders. The gait pattern was observed by synchronizing the contraction of PM, GM, QF and SM, and relaxation of BF of the ipsilateral side together with the reversed patterns in the contralateral side, and then switching the phase by every step. The gait pattern in dysfunction of PM or GM muscles was also observed by disconnecting the corresponding air cylinders. RESULTS: The synchronized contraction of PM, GM, QF and SM generates the force to tilt the upper body to ipsilateral side, followed by elevation of the lower limb together with the forward rotation of the pelvis in the contralateral side to swing the leg forward. The next step was generated by reversing the contraction phase at the landing of the swung leg. The dysfunction of PM muscle disabled effective gait in the model, while GM did not. SIGNIFICANCE: The bipedal android model indicated that the psoas major muscles play a crucial role in bipedal walking in human.


Assuntos
Marcha , Caminhada , Marcha/fisiologia , Humanos , Extremidade Inferior/fisiologia , Músculo Esquelético/fisiologia , Músculo Quadríceps/fisiologia , Caminhada/fisiologia
12.
Gait Posture ; 93: 198-204, 2022 03.
Artigo em Inglês | MEDLINE | ID: mdl-35183836

RESUMO

BACKGROUND: Ankle injuries can foster maladaptive changes in nervous system function that predisposes patients to subsequent injury. Patients are often placed in a dynamic boot immobilizer (BI) following injury; however, little is known about the effects of this treatment on neuromechanical function. RESEARCH QUESTION: We aimed to determine the effect of 72 h of BI-use on neural excitability and lower extremity joint motion in a healthy cohort. METHODS: Twelve uninjured individuals (20.8 ± 1.4 yrs, 1.7 ± 0.1 m, 75.2 ± 9.9 kg) participated in this crossover study. Neural excitability and lower extremity kinematics were assessed before and after 72 h of BI or compression sock (CS) use. Neural excitability was assessed via the Hoffmann (H) reflex and transcranial magnetic stimulation of the motor cortex by measuring muscle activation at the tibialis anterior, peroneus longus, and soleus of the immobilized extremity. Three-dimensional lower extremity joint angles were assessed while participants walked on a treadmill. Repeated-measures analyses of variance detected changes in neural excitability and peak joint angles across time-points and testing conditions, while statistical parametric mapping (SPM) was implemented to determine continuous joint angle changes (α = 0.05). RESULTS: Pre-BI to post-BI, HMax:MMax ratio (F = 6.496; p = 0.031) significantly decreased. The BI did not alter resting motor threshold (F = 0.601; p = 0.468), or motor evoked potential amplitudes (F > 2.82; p > 0.608). Significant changes in peak knee and hip angles in the frontal and transverse planes were observed (p < 0.05), with no changes at the ankle. SPM analyses revealed significant hip and knee changes in range of motion (p < 0.05). SIGNIFICANCE: Decreased measures of reflex but not corticospinal excitability suggest that BI-use for 72 h unloaded the joint enough to generate peripheral changes, but not the CNS, as has been described in casting models. Further, kinematic changes were observed in proximal lower extremity joints, likely due to swing-phase adaptations while wearing the BI.


Assuntos
Tornozelo , Córtex Motor , Articulação do Tornozelo/fisiologia , Fenômenos Biomecânicos , Estudos Cross-Over , Humanos , Extremidade Inferior/fisiologia , Músculo Esquelético/fisiologia
13.
J Therm Biol ; 104: 103187, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-35180966

RESUMO

Plyometric training has been used in several sports and fitness programs to improve jumping ability and explosive strength, both in individual and team sports. Eccentric muscle actions, such as those performed during plyometric jumps, induce muscle damage and consequently a rise in skin temperature (Tsk). Thus, the purpose of this study is to assess the response of infrared thermography measurement as an indirect marker of muscle damage after a protocol of plyometric jumps in physically active subjects. Therefore, for the aim of this study ten male subjects with no previous experience in plyometric training participated in the research (age 22.5 ± 3.3 years, weight 71.7 ± 11.0 kg, height 171.1 ± 5.3 cm, and fat mass 15.5 ± 4.7%). To assess the muscle damage, countermovement jump (CMJ), creatine kinase (CK), delayed-onset muscle soreness (DOMS) and infrared thermography (IRT) were measured at 24, 48, and 72 h after plyometric exercise. The acute exercise protocol of plyometric jumps induced muscle damage, as shown by the CK and DOMS (24 and 48 h, p < 0.05) but no statistical difference was shown between the moments analyzed in Tsk (warm zone). Nevertheless, when comparing baseline to 48h, a moderate effect was found in the Tsk (warm zone) for anterior right thigh (ES = 1.1) and posterior left thigh (ES = 0.9) and large effect was found for anterior left thigh (ES = 1.4) and posterior right thigh (ES = 1.3). A moderate effect in the Tsk (warm zone) was found for posterior right and left thigh (ES = 0.9 and ES = 1.1, respectively) when comparing baseline to 72h of IRT. These results suggest that a plyometric jumping session alters CK and DOMS, as well as the thigh's skin temperature in an evident way, bringing up a possible relation with markers of muscle damage.


Assuntos
Músculo Esquelético/fisiopatologia , Exercício Pliométrico , Temperatura Cutânea/fisiologia , Termografia , Adulto , Biomarcadores/análise , Creatina Quinase/sangue , Humanos , Raios Infravermelhos , Extremidade Inferior/fisiologia , Masculino , Músculo Esquelético/diagnóstico por imagem , Músculo Esquelético/lesões , Mialgia/etiologia , Mialgia/fisiopatologia , Adulto Jovem
14.
J Electromyogr Kinesiol ; 63: 102639, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-35131602

RESUMO

The purpose of this research was to compare children's lower extremity muscle activity and kinematics while walking at fast pace and training at fast speeds with and without motor-assistance on a pediatric-modified motor-assisted elliptical. Twenty-one children without disabilities were recruited and fifteen completed all three training conditions at self-selected fast pace. Repeated-measures ANOVAs identified muscle demand (peak, mean, duration) differences across device conditions and fast walking. Root mean square error compared overall kinematic profiles and statistical parametric mapping identified kinematic differences between conditions. Motor-assisted training reduced lower extremity muscle demands compared to training without the motor's assistance (16 of 21 comparisons) and to fast walking (all but one comparison). Training without the motor's assistance required less muscle effort than fast walking (16 of 21 comparisons). Kinematic differences between device conditions and fast walking were greater distally (thigh, knee, ankle) than proximally (trunk, pelvis, hip). In summary, transitioning from training with to without the motor's assistance promoted progressively greater activity across the lower extremity muscles studied, with sagittal plane kinematic changes most apparent at the distal joints. Our findings highlight how motor-assistance can be manipulated to customize physiologic challenges to lower extremity muscles prior to fast overground walking.


Assuntos
Músculo Esquelético , Caminhada , Fenômenos Biomecânicos , Criança , Marcha/fisiologia , Humanos , Extremidade Inferior/fisiologia , Músculo Esquelético/fisiologia , Caminhada/fisiologia , Velocidade de Caminhada
15.
PLoS One ; 17(1): e0262507, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35020757

RESUMO

This study sought to determine whether lower extremity muscle size, power and strength could be a determinant of whole-body maximal aerobic performance in athletes. 20 male and 19 female young athletes (18 ± 4 years) from various sporting disciplines participated in this study. All athletes performed a continuous ramp-incremental cycling to exhaustion for the determination of peak oxygen uptake ([Formula: see text]: the highest [Formula: see text] over a 15-s period) and maximal power output (MPO: power output corresponding to [Formula: see text]). Axial scanning of the right leg was performed with magnetic resonance imaging, and anatomical cross-sectional areas (CSAs) of quadriceps femoris (QF) and hamstring muscles at 50% of thigh length were measured. Moreover, bilateral leg extension power and unilateral isometric knee extension and flexion torque were determined. All variables were normalised to body mass, and six independent variables ([Formula: see text], CSAs of thigh muscles, leg extension power and knee extension and flexion torque) were entered into a forward stepwise multiple regression model with MPO being dependent variable for males and females separately. In the males, [Formula: see text] was chosen as the single predictor of MPO explaining 78% of the variance. In the females, MPO was attributed to, in the order of importance, [Formula: see text] (p < 0.001) and the CSA of QF (p = 0.011) accounting for 84% of the variance. This study suggests that while oxygen transport capacity is the main determinant of MPO regardless of sex, thigh muscle size also has a role in whole-body maximal aerobic performance in female athletes.


Assuntos
Atletas/estatística & dados numéricos , Desempenho Atlético/fisiologia , Exercício Físico , Extremidade Inferior/fisiologia , Força Muscular , Músculo Esquelético/fisiologia , Adolescente , Adulto , Anatomia Transversal , Fenômenos Biomecânicos , Feminino , Humanos , Masculino , Adulto Jovem
16.
Eur J Appl Physiol ; 122(3): 769-779, 2022 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-35038023

RESUMO

PURPOSE: The force-velocity relationship of muscular contraction has been extensively studied. However, previous research has focussed either on isolated muscle or single-joint movements, whereas human movement consists of multi-joint movements (e.g. squatting). Therefore, the purpose of this study was to investigate the force-velocity relationship of isovelocity squatting. METHODS: Fifteen male participants (24 ± 2 years, 79.8 ± 9.1 kg, 177.5 ± 6 cm) performed isovelocity squats on a novel motorised isovelocity device (Kineo Training System) at three concentric (0.25, 0.5, and 0.75 m s-1) and three eccentric velocities (- 0.25, - 0.5, and - 0.75 m s-1). Peak vertical ground reaction forces, that occurred during the isovelocity phase, were collected using dual force plates (2000 Hz) (Kistler, Switzerland). RESULTS: The group mean squat force-velocity profile conformed to the typical in vivo profile, with peak vertical ground reaction forces during eccentric squatting being 9.5 ± 19% greater than isometric (P = 0.037), and occurring between - 0.5 and - 0.75 m s-1. However, large inter-participant variability was identified (0.84-1.62 × isometric force), with some participants being unable to produce eccentric forces greater than isometric. Sub-group analyses could not identify differences between individuals who could/could not produce eccentric forces above isometric, although those who could not tended to be taller. CONCLUSIONS: These finding suggest that variability exists between participants in the ability to generate maximum eccentric forces during squatting, and the magnitude of eccentric increase above isometric cannot be predicted solely based on a concentric assessment. Therefore, an assessment of eccentric capabilities may be required prior to prescribing eccentric-specific resistance training.


Assuntos
Extremidade Inferior/fisiologia , Contração Muscular/fisiologia , Músculo Esquelético/fisiologia , Fenômenos Biomecânicos , Humanos , Masculino , Força Muscular/fisiologia , Postura , Adulto Jovem
17.
Med Sci Sports Exerc ; 54(3): 399-407, 2022 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-34711709

RESUMO

PURPOSE: The physiological response induced by acute prolonged sitting is not fully understood. Therefore, we examined the effects of 8-h constant sitting on microcirculation and associated factors in the lower extremity among healthy males. We also evaluated the protective effects of lower-pressure thigh-length elastic compression garments on these parameters. METHODS: Nine healthy males (age, 22.6 ± 1.4 yr; body mass index, 22.4 ± 1.8 kg·m-2) completed the 8-h constant sitting experiment. Following baseline measurements, each subject was randomized to wear a lower-pressure elastic garment on the right or left leg from the inguinal region to the ankle joint, with the noncompressed contralateral leg as a control. Circumferences of the calf and malleolus, extracellular water contents, blood flow and shear rate of the dorsal metatarsal artery, and oxygen dynamics in the gastrocnemius muscles were measured in both extremities before and during 8-h constant sitting. RESULTS: Compared with baseline values, 8-h constant sitting caused enlargement of circumferences (calf, 2.4% ± 0.7%; malleolus, 2.7% ± 1.4%), retention of extracellular water in lower extremity muscles (10.1% ± 1.78%), deterioration of the blood flow (61.4% ± 16.2% of baseline) and shear rate of the dorsal metatarsal artery, and decrease in oxygenated hemoglobin and total hemoglobin levels in the gastrocnemius muscle (P < 0.05, respectively). When subjects wore the lower-pressure thigh-length compression garment, a significant reduction of these effects was observed (P < 0.05, for all). CONCLUSIONS: Prolonged sitting for 8 h induced edema, as well as deterioration of the arterial blood flow, shear rate, and microcirculation in lower limb muscles. Conversely, application of the lower-pressure elastic garment successfully prevented the pathophysiological deterioration associated with prolonged sitting.


Assuntos
Extremidade Inferior/irrigação sanguínea , Extremidade Inferior/fisiologia , Músculo Esquelético/irrigação sanguínea , Músculo Esquelético/fisiologia , Fluxo Sanguíneo Regional/fisiologia , Postura Sentada , Meias de Compressão , Humanos , Masculino , Adulto Jovem
18.
Med Sci Sports Exerc ; 54(3): 456-465, 2022 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-34652335

RESUMO

PURPOSE: This study aimed to examine the changes in muscle contractile function, voluntary activation, and muscle damage after lower limb resistance training (RT), intermittent sprint exercise, and concurrent training (CT). METHODS: Ten male, recreational team sport athletes with a history of RT participated in a randomized crossover study involving an intermittent sprint protocol (ISP), lower limb RT, and CT (ISP and RT separated by 1 h). Before (PRE), immediately after (POST), 24 h and 48 h after each exercise condition, quadriceps muscle activation, voluntary activation, muscle contractile function (evoked twitch responses), creatine kinase, muscle soreness, and Profile of Mood States (POMS)-fatigue were recorded. RESULTS: Quadriceps contractile function was hampered in all conditions, with a significantly greater decline observed POST RT (58.4% ± 18.0%) and CT (54.8% ± 8.6%) compared with ISP (35.9% ± 10.7%, P < 0.05), recovering at 48 h after all exercise conditions. POMS-fatigue ratings increased at POST in all conditions with CT and ISP eliciting the greatest increase, returning to baseline 48 h after all exercise conditions. Quadriceps muscle soreness remained elevated from PRE at 48 h after all exercise conditions. No changes across time were observed for voluntary activation and quadriceps surface EMG amplitude after any exercise condition. The volume and load lifted in the RT session was unaffected by previous intermittent exercise (ISP) in CT. CONCLUSIONS: RT impairs contractile function, which is not exacerbated when performed 1 h after the ISP. Contractile function after all exercise conditions displayed the same recovery profile (48 h) despite the postexercise decrement being smaller after the ISP compared with RT and CT. Previous intermittent sprint exercise does not negatively affect the volume of exercise performed in a lower limb RT session.


Assuntos
Desempenho Atlético/fisiologia , Extremidade Inferior/fisiologia , Músculo Quadríceps/fisiologia , Treinamento de Força/métodos , Corrida/fisiologia , Esportes de Equipe , Adulto , Estudos Cross-Over , Eletromiografia , Humanos , Masculino , Adulto Jovem
19.
J Sports Sci ; 40(5): 561-570, 2022 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-34796778

RESUMO

The corticospinal responses to high-intensity and low-intensity strength-training of the upper limb are modulated in an intensity-dependent manner. Whether an intensity-dependent threshold occurs following acute strength training of the knee extensors (KE) remains unclear. We assessed the corticospinal responses following high-intensity (85% of maximal strength) or low-intensity (30% of maximal strength) KE strength-training with measures taken during an isometric KE task at baseline, post-5, 30 and 60-min. Twenty-eight volunteers (23 ± 3 years) were randomized to high-intensity (n = 11), low-intensity (n = 10) or to a control group (n = 7). Corticospinal responses were evoked with transcranial magnetic stimulation at intracortical and corticospinal levels. High- or low-intensity KE strength-training had no effect on maximum voluntary contraction force post-exercise (P > 0.05). High-intensity training increased corticospinal excitability (range 130-180%) from 5 to 60 min post-exercise compared to low-intensity training (17-30% increase). Large effect sizes (ES) showed that short-interval cortical inhibition (SICI) was reduced only for the high-intensity training group from 5-60 min post-exercise (24-44% decrease) compared to low-intensity (ES ranges 1-1.3). These findings show a training-intensity threshold is required to adjust CSE and SICI following strength training in the lower limb.


Assuntos
Córtex Motor , Treinamento de Força , Eletromiografia , Potencial Evocado Motor/fisiologia , Humanos , Contração Isométrica/fisiologia , Extremidade Inferior/fisiologia , Córtex Motor/fisiologia , Músculo Esquelético/fisiologia , Tratos Piramidais/fisiologia
20.
Eur J Appl Physiol ; 122(2): 447-457, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-34797438

RESUMO

PURPOSE: Limited information is available on the association between muscle material properties and sprint performance. We aimed to identify whether and how the elasticity of passive and active muscle of the medial gastrocnemius (MG) is related to sprint performance. METHODS: MG shear wave speed was measured under passive and active (20%, 50%, 80% of maximal voluntary contraction [MVC]) conditions, with ultrasound shear wave elastography, in 18 male sprinters. Passive and active ankle joint stiffness was assessed by applying a short-range fast stretch during 0%, 20%, 50%, and 80% MVC of plantar flexion. Additionally, rate of torque development (RTD) during explosive plantar flexion was measured. RESULTS: Passive and active MG shear wave speed was negatively correlated with 100-m race time. Passive MG shear wave speed was positively correlated with RTD, and RTD was negatively correlated with 100-m race time. MG shear wave speed at 50% and 80% MVC showed a positive correlation with ankle joint stiffness at the corresponding contraction level, and ankle joint stiffness at 50% and 80% MVC showed negative correlations with 100-m race time. These correlations were significant even after controlling for MVC torque. CONCLUSION: Our findings indicate that passive and active muscle elasticity of plantar flexor is important to achieve superior sprint performance. Specifically, high elasticity of passive MG could be related to superior sprint performance through high explosive torque production. In contrast, high elasticity of active MG at moderate-to-high intensity is likely related to high sprint performance through high ankle joint stiffness.


Assuntos
Desempenho Atlético/fisiologia , Técnicas de Imagem por Elasticidade , Extremidade Inferior/diagnóstico por imagem , Extremidade Inferior/fisiologia , Músculo Esquelético/diagnóstico por imagem , Músculo Esquelético/fisiologia , Corrida/fisiologia , Humanos , Masculino , Contração Muscular/fisiologia , Torque , Adulto Jovem
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