Influence of floor inclination on handle push and pull forces production of the upper limb.

Floor inclination can alter hand force production, and lower limb kinetics, affecting control operations, and threatening operator safety in various domains, such as aviation, naval, construction industry, or agriculture. This study investigates the effects of different floor inclinations, on handle push or pull force production. Participants performed maximal isometric contraction tasks requiring to exert a maximal voluntary force either by pulling or pushing a handle, at different floor inclinations from -30° to +30° about the transverse and longitudinal axes.

Influence of Pedal Interface During Pedaling With the Upper Versus Lower Limbs: A Pilot Analysis of Torque Performance and Muscle Synergies.

Pedaling is a physical exercise practiced with either the upper or the lower limbs. Muscle coordination during these exercises has been previously studied using electromyography and synergy analysis, and three to four synergies have been identified for the lower and upper limbs. The question of synergy adaptabilities has not been investigated during pedaling with the upper limbs, and the impact of various modalities is yet not known.

Trial- vs. cycle-level detrending in the analysis of cyclical biomechanical data.

Biomechanical time series may contain low-frequency trends due to factors like electromechanical drift, attentional drift and fatigue. Existing detrending procedures are predominantly conducted at the trial level, removing trends that exist over finite, adjacent time windows, but this fails to consider what we term 'cycle-level trends': trends that occur in cyclical movements like gait and that vary across the movement cycle, for example: positive and negative drifts in early and late gait phases, respectively. The purposes of this study were to describe cycle-level detrending and to investigate the frequencies with which cycle-level trends (i) exist, and (ii) statistically affect results.

An interdisciplinary framework to optimize the anticipation skills of high-level athletes using virtual reality.

The ambition of our contribution is to show how an interdisciplinary framework can pave the way for the deployment of innovative virtual reality training sessions to improve anticipation skills in top-level athletes. This improvement is so challenging that some authors say it is like "training for the impossible". This framework, currently being implemented as part of a project to prepare athletes for the 2024 Olympic Games in Paris, based on the ecological-dynamics approach to expertise, is innovative in its interdisciplinary nature, but also and above all because it overcomes the limitations of more traditional training methods in the field designed to optimize anticipation skills in top-level athletes.

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.

Evolution of muscle coordination and mechanical output following four weeks of arm cranking submaximal training.

Unlabelled: Muscle synergies is extensively studied to understand how the neuromusculoskeletal system deals with abundancy. The synergies represent covariant muscles that acts as building blocks for movement production. Nevertheless, little is known on how those synergies evolve following training, learning and expertise.

Subject specific muscle synergies and mechanical output during cycling with arms or legs.

Background: Upper (UL) and lower limb (LL) cycling is extensively used for several applications, especially for rehabilitation for which neuromuscular interactions between UL and LL have been shown. Nevertheless, the knowledge on the muscular coordination modality for UL is poorly investigated and it is still not known whether those mechanisms are similar or different to those of LL. The aim of this study was thus to put in evidence common coordination mechanism between UL and LL during cycling by investigating the mechanical output and the underlying muscle coordination using synergy analysis.

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.

Online sonification improves cycling performance through kinematic and muscular reorganisations.

Based on a previous study that demonstrated the beneficial effects of sonification on cycling performance, this study investigated which kinematic and muscular activities were changed to pedal effectively. An online error-based sonification strategy was developed, such that, when negative torque was applied to the pedal, a squeak sound was produced in real-time in the corresponding headphone. Participants completed four 6-min cycling trials with resistance values associated with their first ventilatory threshold.

A multivariate statistical strategy to adjust musculoskeletal models.

In musculoskeletal modelling, adjusting model parameters is challenging. This paper proposes a multivariate statistical methodology to adjust muscle force-generating parameters optimally. Dynamic residuals are minimized as muscle force-generating parameters are varied (maximal isometric force, optimal fiber length, tendon slack length and pennation angle).

Is Motorized Treadmill Running Biomechanically Comparable to Overground Running? A Systematic Review and Meta-Analysis of Cross-Over Studies.

Background: Treadmills are often used in research, clinical practice, and training. Biomechanical investigations comparing treadmill and overground running report inconsistent findings.

Objective: This study aimed at comparing biomechanical outcomes between motorized treadmill and overground running.

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.

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.

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.

The Influence of the 'Trier Social Stress Test' on Free Throw Performance in Basketball: An Interdisciplinary Study.

The aim of the present study was to explore the relationship between stress and sport performance in a controlled setting. The experimental protocol used to induce stress in a basketball free throw was the Trier Social Stress Test (TSST) and its control condition (Placebo-TSST). Participants (n = 19), novice basketball players but trained sportspersons, were exposed to two counterbalanced conditions in a crossover design.

Functional coordination of muscles underlying changes in behavioural dynamics.

The dynamical systems approach addresses Bernstein's degrees of freedom problem by assuming that the neuro-musculo-skeletal system transiently assembles and dismantles its components into functional units (or synergies) to meet task demands. Strikingly, little is known from a dynamical point of view about the functioning of the muscular sub-system in this process. To investigate the interaction between the dynamical organisation at muscular and behavioural levels, we searched for specific signatures of a phase transition in muscular coordination when a transition is displayed at the behavioural level.

A scale-based approach to interdisciplinary research and expertise in sports.

After more than 20 years since the introduction of ecological and dynamical approaches in sports research, their promising opportunity for interdisciplinary research has not been fulfilled yet. The complexity of the research process and the theoretical and empirical difficulties associated with an integrated ecological-dynamical approach have been the major factors hindering the generalisation of interdisciplinary projects in sports sciences. To facilitate this generalisation, we integrate the major concepts from the ecological and dynamical approaches to study behaviour as a multi-scale process.

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.

One- and multi-segment foot models lead to opposite results on ankle joint kinematics during gait: Implications for clinical assessment.

Background: Biomechanical models representing the foot as a single rigid segment are commonly used in clinical or sport evaluations. However, neglecting internal foot movements could lead to significant inaccuracies on ankle joint kinematics. The present study proposed an assessment of 3D ankle kinematic outputs using two distinct biomechanical models and their application in the clinical flat foot case.

Does wearing shoes affect your biomechanical efficiency?

Studies involving minimalist shoes have dramatically increased this past 10 years. While a deeper knowledge of the related modifications has ensued regarding the kinematics, electromyographic, and dynamic patterns, little is known regarding the modifications at the muscle forces and muscle fiber levels. The aim of the present study was to assess at a muscular level the modifications brought up when running barefoot, using 0mm midsole height running shoe, or using classical midsole height running shoes.

Shoe drop has opposite influence on running pattern when running overground or on a treadmill.

Purpose: Minimalist running shoes are designed to induce a foot strike made more with the forepart of the foot. The main changes made on minimalist shoe consist in decreasing the height difference between fore and rear parts of the sole (drop). Barefoot and shod running have been widely compared on overground or treadmill these last years, but the key characteristic effects of minimalist shoes have been yet little studied.

A multi-level approach to investigate the control of an input device: application to a realistic pointing task.

Unlabelled: This study investigates the subjects' performance during realistic conditions of control of a joystick. An adapted reciprocal aiming task consisting in driving a virtual vehicle along a slalom course as fast as possible was performed while accuracy constraints were manipulated. Realistic dynamical Interface Screen Relationship between the joystick displacements and the displacements of the vehicle was simulated.