Increasing load carriage and running speed differentially affect the magnitude, variability and coordination patterns of muscle forces.

The study aims to investigate the effects of different loads and speed during running on inter- and intra-individual muscle force amplitudes, variabilities and coordination patterns. Nine healthy participants ran on an instrumentalized treadmill with an empty weight vest at two velocities (2.6 m/s and 3.

Influence of Force-Length Relationship and Task-Specific Constraints on Finger Force-Generating Capacities.

Grip strength loss in extended and flexed wrist postures has been explained by reduced force-generating capacities of extrinsic finger flexor resulting from non-optimal length, owing to the force-length relationship. Recent works suggested that other muscles, especially wrist extensors, participate in this grip strength loss. The objective of this study was to clarify the role of the force-length relationship in finger force production.

High-intensity training with short and long intervals regulate cortical neurotrophic factors, apoptosis markers and chloride homeostasis in rats with stroke.

The optimal endurance exercise parameters remain to be defined to potentiate long-term functional recovery after stroke. We aim to assess the effects of individualized high-intensity interval training (HIIT) with either long or short intervals on neurotrophic factors and their receptors, apoptosis markers and the two-main cation-chloride cotransporters in the ipsi- and contralesional cerebral cortices in rats with cerebral ischemia. Endurance performance and sensorimotor functions were also assessed METHODS: Rats with a 2 h transient middle cerebral artery occlusion (tMCAO) performed work-matched HIIT4 (intervals: 4 min) or HIIT1 (intervals: 1 min) on treadmill for 2 weeks.

Effects of Different Hangboard Training Intensities on Finger Grip Strength, , and .

Climbing-specific training programs on hangboards are often based on dead-hang repetitions, but little is known about the real intensity applied during such effort. The aim of this study was to quantify and compare the effects of different training intensities (maximal, high submaximal, and low submaximal intensities) on the fingers' physiological capabilities using a hangboard fitted with force sensors. In total, 54 experienced climbers (13 women and 41 men) were randomly divided into four groups, with each group following different training intensity programs: maximal strength program performed at 100% of the maximal finger strength (MFS; F100), intermittent repetitions at 80% MFS (F80), intermittent repetitions at 60% MFS (F60), and no specific training (control group).

Inter-strides variability affects internal foot tissue loadings during running.

Running overuse injuries result from an imbalance between repetitive loadings on the anatomical structures and their ability to adapt to these loadings. Unfortunately, the measure of these in-vivo loadings is not easily accessible. An optimal amount of movement variability is thought to decrease the running overuse injury risk, but the influence of movement variability on local tissue loading is still not known.

Time-dependent cortical plasticity during moderate-intensity continuous training versus high-intensity interval training in rats.

The temporal pattern of cortical plasticity induced by high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) is required to clarify their relative benefits to prevent neurological disorders. The purpose of this study is to define the time-dependent effects of work-matched HIIT and MICT on cortical plasticity, endurance, and sensorimotor performances over an 8-week training period in healthy rats. Adult healthy rats performed incremental exercise tests and sensorimotor tests before and at 2, 4, and 8 weeks of training.

Anatomical basis for ultrasound-guided infiltration of the saphenous nerve in the subsartorial canal.

The present work is aimed studying the visibility and position of the vasto-adductor membrane with ultrasonography and demonstrating that injection performed under this membrane allows to infiltrate the saphenous nerve. It was analyzed with ultrasonography in four cadaveric subjects and in 13 volunteers. This membrane was clearly visible and methylene blue was located underneath it after injection in all cadaveric subjects.

Is High-Intensity Interval Training Suitable to Promote Neuroplasticity and Cognitive Functions after Stroke?

Stroke-induced cognitive impairments affect the long-term quality of life. High-intensity interval training (HIIT) is now considered a promising strategy to enhance cognitive functions. This review is designed to examine the role of HIIT in promoting neuroplasticity processes and/or cognitive functions after stroke.

Effects of Different High-Intensity Interval Training Regimens on Endurance and Neuroplasticity After Cerebral Ischemia.

Background And Purpose: The objective is to compare the effects of high-intensity interval training (HIIT) with long versus short intervals on endurance and motor performance. Their influence on neuroplasticity markers is assessed in the ipsilesional and contralesional cortex and hippocampus since their remodeling could improve functional recovery.

Methods: Rats performed work-matched HIIT4 (long intervals: 4 minutes) or HIIT1 (short intervals: 1 minute) on treadmill for 2 weeks following transient middle cerebral artery occlusion.

Modelling force-length-activation relationships of wrist and finger extensor muscles.

The wrist and finger extensors play a crucial role in the muscle coordination during grasping tasks. Nevertheless, few data are available regarding their force-generating capacities. The objective of this study was to provide a model of the force-length-activation relationships of the hand extensors using non-invasive methods.

Intentional Switching Between Bimanual Coordination Patterns in Older Adults: Is It Mediated by Inhibition Processes?

The study investigated the consequences of age-related decline in inhibition processes on intentional switching between bimanual coordination patterns. Fifteen young (24±2.8 years) and 20 older adults (69±5.

Complex couplings between joints, muscles and performance: the role of the wrist in grasping.

The relationship between posture, muscle length properties and performance remains unclear, because of a lack of quantitative data. Studies on grasping tasks suggested that wrist position could favour the extrinsic finger flexor in regards to their length to maximise grip force performance. The present study aimed at providing quantitative evidence of the links between wrist posture, muscle capacities and grip capabilities.

The stiff plate location into the shoe influences the running biomechanics.

The changes in running biomechanics induced by an increased longitudinal bending stiffness (stiff plates added into the shoes) have been well investigated, but little is known concerning the effects of the stiff plate location into the shoe on running biomechanics. Fourteen male recreational runners ran at two participant-specific running speeds (3.28 ± 0.

Does an increase in energy return and/or longitudinal bending stiffness shoe features reduce the energetic cost of running?

Purpose: This study focused on the effects of shoe energy return and shoe longitudinal bending stiffness on the energetic cost and biomechanics of running.

Methods: The energetic cost of running and biomechanical variables altering running economy (ground contact times, stride frequency, vertical and leg stiffness, ground reaction force impulses, alignment between the resultant ground reaction force and the leg) were measured for nineteen male recreational runners. Participants ran overground under their ventilatory anaerobic threshold (10.

Performing pull-ups with small climbing holds influences grip and biomechanical arm action.

Pull-ups are often used by sport-climbers and other athletes to train their arm and back muscle capabilities. Sport-climbers use different types of holds to reinforce finger strength concomitantly. However, the effect of grip types on pull-up performance had not previously been investigated.

Force-Length Relationship Modeling of Wrist and Finger Flexor Muscles.

Introduction: Because the hand joints possess a broad range of motion, the muscle length can vary importantly which might result in significant variations of the muscle force-generating capacities. However, facing the complexity of this musculoskeletal system, no study has examined the effect of hand muscle length change on muscle force. This study aimed to characterize the force-length relationship of muscles involved in wrist and metacarpophalangeal flexion.

Effects of hand configuration on muscle force coordination, co-contraction and concomitant intermuscular coupling during maximal isometric flexion of the fingers.

Purpose: The mechanisms governing the control of musculoskeletal redundancy remain to be fully understood. The hand is highly redundant, and shows different functional role of extensors according to its configuration for a same functional task of finger flexion. Through intermuscular coherence analysis combined with hand musculoskeletal modelling during maximal isometric hand contractions, our aim was to better understand the neural mechanisms underlying the control of muscle force coordination and agonist-antagonist co-contraction.

Impaired corticomuscular coherence during isometric elbow flexion contractions in humans with cervical spinal cord injury.

After spinal cord injury (SCI), the reorganization of the neuromuscular system leads to increased antagonist muscles' co-activation-that is, increased antagonist vs. agonist muscles activation ratio-during voluntary contractions. Increased muscle co-activation is supposed to result from reduced cortical influences on spinal mechanisms inhibiting antagonist muscles.

The Effect of Aging on Muscular Dynamics Underlying Movement Patterns Changes.

Aging leads to alterations not only within the complex subsystems of the neuro-musculo-skeletal system, but also in the coupling between them. Here, we studied how aging affects functional reorganizations that occur both within and between the behavioral and muscular levels, which must be coordinated to produce goal-directed movements. Using unimanual reciprocal Fitts' task, we examined the behavioral and muscular dynamics of older adults (74.

Active tuning of stroke-induced vibrations by tennis players.

This paper investigates how tennis players control stroke-induced vibration. Its aim is to characterise how a tennis player deals with entering vibration waves or how he/she has the ability to finely adjust them. A specific experimental procedure was designed, based on simultaneously collecting sets of kinematic, vibration and electromyographic data during forehand strokes using various commercial rackets and stroke intensities.

Assessment of the risk and biomechanical consequences of lateral epicondylalgia by estimating wrist and finger muscle capacities in tennis players.

Previous studies suggested that a pronounced weakness of the extensor muscles relative to the flexor muscles could increase the risk of occurrence of lateral epicondylalgia. This study investigates this hypothesis by estimating the ratio of extensor to flexor muscle capacities among healthy non-players (n = 10), healthy tennis players (n = 20), symptomatic players (n = 6), and players who have recovered from lateral epicondylalgia (n = 6). Maximum net joint moments in flexion or extension were measured during seven tasks involving the voluntary contraction of wrist and fingers.

The effects of player grip on the dynamic behaviour of a tennis racket.

The aim of this article is to characterise the extent to which the dynamic behaviour of a tennis racket is dependent on its mechanical characteristics and the modulation of the player's grip force. This problem is addressed through steps involving both experiment and modelling. The first step was a free boundary condition modal analysis on five commercial rackets.

Fatigue- and training-related changes in 'beta' intermuscular interactions between agonist muscles.

The synchronous activation of the muscles involved in force production is crucial for the neuromuscular performance, but the underlying mechanisms remain to be fully elucidated. Our aim was thus to contribute to understand the mechanisms involved in the synergistic activation of agonist muscles. Through wavelet-based time-frequency analysis, this study investigated the modulation of 'beta' intermuscular interactions (IM) during maximum isometric knee extensions performed before and after repetitive submaximal fatiguing contractions.

Performing Isometric Force Control in Combination with a Cognitive Task: A Multidimensional Assessment.

Introduction: We used a multidimensional approach to study isometric force control in single and dual-task conditions.

Methods: Multiple measures of performance, efficiency, variability, and structural interference were calculated at low and higher force levels under single (force maintenance) and dual-task (force maintenance and reaction time) conditions.

Results: Reaction time and signal-to-noise ratio were larger in the dual-task conditions.

Quantifying foot deformation using finite helical angle.

Foot intrinsic motion originates from the combination of numerous joint motions giving this segment a high adaptive ability. Existing foot kinematic models are mostly focused on analyzing small scale foot bone to bone motions which require both complex experimental methodology and complex interpretative work to assess the global foot functionality. This study proposes a method to assess the total foot deformation by calculating a helical angle from the relative motions of the rearfoot and the forefoot.