Jacques Duchateau

Université Libre de Bruxelles | ULB · Laboratory of Applied Biology and Neurophysiology

The aim of our study was to compare the effects of two different plyometric training programs (targeting knee extensors or plantar flexors) on jump height and strength of leg muscles. Twenty‐nine male basketball players were assigned to the knee‐flexed (KF), knee‐extended (KE), or control groups. In addition to regular training, the KF group perfor...

The aim of the study was to assess neuromuscular changes during an intermittent fatiguing task designed to replicate fundamental actions and ergonomics of road race motorcycling. Twenty-eight participants repeated a sequence of submaximal brake-pulling and gas throttle actions, interspaced by one maximal brake-pulling, until failure. During the sub...

Rapid force production and its transmission to the skeleton are important factors in movements that involve the stretch-shortening cycle. Plyometric exercises are known to augment this cycle and thereby improve the neuromechanical function of the muscle. However, the training exercises that maximize translation of these gains to sports performance...

Ageing is accompanied by numerous changes within the sensory and motor components of the muscle spindle pathway. To further document these age-related changes, this study compared the characteristics of the Hoffmann (H) reflex and M wave, evoked with several pulse durations, between young and old adults. The H-reflex and M-wave recruitment curves w...

Research in movement science aims at unravelling mechanisms and designing methods for restoring and maximizing human functional capacity, and many techniques provide access to neural adjustments (acute changes) or long-term adaptations (chronic changes) underlying changes in movement capabilities. First described by Paul Hoffmann over a century ago...

Ageing is accompanied by numerous changes within the sensory and motor component of the muscle spindle pathway. To further document these age-related changes, this study compared the characteristics of the Hoffmann (H) reflex and M wave, evoked with several pulse durations, between young and old adults. The H-reflex and M-wave recruitment curves we...

We analyzed the time course of changes in muscle activity of the prime mover and synergist muscles during a sustained brake-pulling action and investigated the relationship between muscle activity and braking force fluctuation (FF). Thirty-two participants performed a continuous fatiguing protocol (CFP) at 30% of maximal voluntary contraction (MVC)...

This study investigated the effects of post-activation potentiation (PAP) on the force output and muscle architecture in plantar flexor muscles. The mechanical response to a single electrical stimulus (twitch), and to two (doublet) and three (triplet) stimuli (10-ms inter-pulse interval) was measured before and after a 6-s maximal voluntary contrac...

The sense of force is suggested to rely in part on proprioceptive inputs when assessed with a force reproduction task. The age-related alterations in proprioceptive system could, therefore, alter the sense of force. This study investigated the effects of tendon vibration on a force reproduction task performed with the wrist flexors in 18 young (20–...

The purpose of our review was to compare the distribution of motor unit properties across human muscles of different sizes and recruitment ranges. Although motor units can be distinguished based on several different attributes, we focused on four key parameters that have a significant influence on the force produced by muscle during voluntary contr...

Fatigue is one of the most common debilitating symptoms reported by persons with multiple sclerosis (MS). It reflects feelings of tiredness, lack of energy, low motivation, and difficulty in concentrating. It can be measured at a specific instant in time as a perception that arises from interoceptive networks involved in the regulation of homeostas...

Maneuvering a motorcycle in racing conditions or for prolonged time is sufficiently demanding that on many occasions forearm muscles reach a state of functional failure when riders cannot properly brake or operate the throttle. This study intends to discriminate which ones of the several dynamometric parameters used in the literature to characteriz...

Key points Changes in corticospinal excitability prior to a contraction may depend on its characteristics, including the rate of torque development. This study compared the specific modulation of cortical and spinal excitability during the preparation phase (last 500 ms before contraction) of fast (ballistic) and ramp contractions of ankle dorsifle...

Training with low-load exercise performed under blood-flow restriction can augment muscle hypertrophy and maximal strength to a similar extent as the classical high-load strength training method. However, the blood-flow restriction method elicits only minor neural adaptations. In an attempt to maximize training-related gains, we propose using other...

Laurent, C, Baudry, S, and Duchateau, J. Comparison of plyometric training with two different jumping techniques on Achilles tendon properties and jump performances. J Strength Cond Res XX(X): 000-000, 2020-This study compared the influence of 10 weeks of plyometric training with 2 different jumping techniques on Achilles tendon properties and the...

The generation of action potentials in intramuscular motor and sensory axons in response to an imposed external current source can evoke muscle contractions and elicit widespread responses throughout the nervous system that impact sensorimotor function. The benefits experienced by individuals exposed to several weeks of treatment with electrical st...

Aim: To assess the change in the contribution of proprioceptive signal from leg muscles in postural control with ageing. Methods: Fifteen young (~23 yr) and fifteen older adults (~68 yr) participated in Experiment 1, which consisted of recording the mean position of the centre of pressure (CoP), CoP path length, CoP velocity, and the amplitude o...

Aim This study investigated the efficacy of a new strength training method on strength gain, hypertrophy, and neuromuscular fatigability. Methods The training exercise consisted of elbow flexion against a load of ~ 70% of one repetition maximal (1RM). A new method (3/7 method) consisting of five sets of an increasing number of repetitions (3 to 7)...

Purpose The objective of the current study was to investigate the mechanisms responsible for the briefer time to failure of a submaximal contraction (C2) when performed 60 min after a similar contraction (C1), and the influence of anodal transcranial direct current stimulation (a-tDCS) applied over the motor cortex on these mechanisms. Methods In...

Fatigue is a disabling symptom that constrains motor performance. It depends on the physiological capabilities that establish the level of fatigability for a given task and the physiological and psychological factors that contribute to perceptions of fatigue [1]. The relative influence of the potential factors that can contribute to fatigue depends...

Background: The Hoffmann (H) reflex can provide relevant information on spinal control of leg muscles during locomotor tasks in young and older adults. Research question: Is the H reflex in the leg muscles differently modulated during stair gait in young and older adults? Method: The H reflex in soleus (SOL) and medial gastrocnemius (MG) (normalize...

The application of a series of extremely high accelerative motor-driven quick releases while muscles contract isometrically (i.e. slack test) has been proposed to assess unloaded velocity in human muscle. This study aimed to measure gastrocnemius medialis fascicle (VF) and tendinous tissues shortening velocity during motor-driven quick releases per...

Purpose: To determine the role of noradrenergic modulation in the control of motor output, we compared the acute effect of Reboxetine (REB), a noradrenaline reuptake inhibitor, to a placebo (PLA) on knee extensors motor performance and cortical and spinal excitability. Methods: Eleven young males took part in two randomized experiments during wh...

Purpose: The present study aimed at comparing knee extensor neuromuscular properties determined with transcutaneous electrical stimulation using two pulse durations before and after a standardized fatigue protocol. Methods: In the first sub-study, 19 healthy participants (ten women and nine men; 28 ± 5 years) took part to two separate testing se...

Purpose: This study investigated the effects of short-term glucocorticoid administration on voluntary activation and intracortical inhibitory and facilitatory circuits. Methods: Seventeen healthy men participated in a pseudo randomized double-blind study to receive either dexamethasone (8 mg·d, n = 9 subjects) or placebo (n = 8 subjects) for 7 d...

Introduction : A recent study (Laurent et al., 2016) indicated that a strength training method (3/7 method) which consists of 5 sets of an incremental number of repetitions during successive sets (from 3 to 7 repetitions), a moderate load (70% of one repetition maximal (1RM)), and very brief rest interval between sets (≤15 s), induced similar incre...

Introduction: The modulation of the Hoffman (H) reflex in soleus (SOL) during the gait cycle highlights the need to adjust the synaptic efficacy between Ia afferents and spinal motoneurones depending on the gait phases (Capaday and Stein, 1986). Such modulation should be even more pronounced during staircase ascent and descent that involve greater...

PurposeThis study investigated the modulation of spinal (group Ia afferents) and corticospinal pathways when young (22.7 ± 1.3 years) and older adults (72.2 ± 7.9 years) stood at the bottom and at the top of a three-step staircase equipped with force platforms. Method Changes in submaximal H-reflex amplitude (H50) and slope of the H-reflex input–ou...

Geriatric patients with acute infection show increased muscle weakness and fatigability but the relative contribution of central and peripheral factors is unclear. Hospitalised patients with acute infection (82 ± 6 years, N = 10) and community-dwelling controls (76 ± 6 years, N = 19) sustained a maximal voluntary isometric contraction of the M. Add...

The force exerted by a muscle during a voluntary contraction depends on the number of motor units recruited for the action and the rates at which they discharge action potentials (rate coding). Over most of the operating range of a muscle, the nervous system controls muscle force by varying both motor unit recruitment and rate coding. Except at rel...

Purpose: The acute effects of a single training session on muscle activity and oxygenation were compared between a new strength training method (3/7 protocol) and a more classical method (4 × 6 and 8 × 6 protocols). Method: All protocols consisted of lifting and lowering a load (70 % 1RM) with the elbow-flexor muscles. The 3/7 protocol involved...

Introduction: Maximal force of the ankle plantar flexor (PF) muscles plays a key role in postural control (1). The decrease in maximal PF force with ageing should therefore contribute to alter balance steadiness in this age group (4). However, some studies reported only modest effects of a strength training programme on bipedal balance control in o...

The evaluation of rate of force development during rapid contractions has recently become quite popular for characterising explosive strength of athletes, elderly individuals and patients. The main aims of this narrative review are to describe the neuromuscular determinants of rate of force development and to discuss various methodological consider...

Aim This study investigated the effect of a new strength training method (3/7 protocol) consisting of 5 sets with an incremental number of repetitions (3 to 7) and very short rest interval between sets (15 s). Material and methods Thirty-eight young subjects were assigned to one of the 3 following protocols and trained 2 times per week for 8 weeks...

This chapter describes the physiology of muscle activation and force generation. It discusses the anatomy of the final common pathway from the nervous system to muscle, the electrical properties of motor neurons and muscle fibers, and the contractile properties of muscle fibers and motor units. The chapter presents the concept of motor unit types a...

This chapter focuses on the basics of surface electromyography (sEMG) and related methods for the study of human motor control and its adaptations. Recordings of voluntary sEMG provide partial information on the mechanisms involved in muscle activity. However, the combination of sEMG and methods based on electrically and magnetically evoked potenti...

Despite flourishing interest in the topic of fatigue-as indicated by the many presentations on fatigue at the 2015 annual meeting of the American College of Sports Medicine-surprisingly little is known about its impact on human performance. There are two main reasons for this dilemma: (1) the inability of current terminology to accommodate the scop...

During exercise, there is a progressive reduction in the ability to produce muscle forces. Processes within the nervous system, as well as within the muscles contribute to this fatigue. In addition to impaired function of the motor system, sensations associated with fatigue, and impairment of homeostasis can contribute to impairment of performance...

Background: The increase in corticospinal excitability in response to anodal transcranial direct current stimulation (a-tDCS) may contribute to decrease neuromuscular fatigability. Objective: This study investigated t he effects of a-tDCS on neuromuscular fatigability in relation with changes in corticospinal excitability. Methods: Eleven adul...

Purpose: To assess the neural mechanisms that limit endurance time, we compared a fatiguing task performed under the influence of reboxetine (REB), a noradrenaline reuptake inhibitor, and placebo (PLA). Methods: Nine male subjects (age: 24 ± 2 yr) participated in this study. The fatiguing task involved repeated 3-s submaximal isometric contracti...

A number of studies over the last few decades have established that the control strategy employed by the nervous system during lengthening (eccentric) differs from those used during shortening (concentric) and isometric contractions. The purpose of this review is to summarize current knowledge on the neural control of lengthening contractions. Afte...

No abstract. Copyright © 2015, Journal of Applied Physiology.

Introduction Previous work revealed the importance of sensory inputs to control balance, with different contribution of vestibular, visual and proprioceptive information (Peterka 2002). Accordingly, the decline in the integrity of the sensory systems with ageing alters balance capacity (Maki et al. 1996). But the effects on the respective contribut...

The present work was designed to investigate the presynaptic modulation of soleus Ia afferents with the direction of the displacement and the position of the center of pressure (CoP) during unperturbed upright standing and exaggerated CoP displacements in young adults. Hoffmann (H) reflex was evoked in the soleus by stimulating the tibial nerve at...

Very few studies have quantified the degree of fatigue characterized by the decline in the maximal voluntary contraction (MVC) force of the trunk extensors induced by the widely used Sørensen test. Measure the degree of fatigue of the trunk extensor muscles induced by the Sørensen test. Eighty young healthy subjects were randomly divided into a con...

The study was undertaken to provide insight into the mechanisms underlying the potentiation of the muscle compound action potential (M wave) after conditioning contractions. M waves were evoked in the tibialis anterior before and after isometric maximal voluntary contractions (MVC) of 1, 3, 6, 10, 30 and 60s, and after 3-s contractions at 10, 30, 5...

This study investigated the effects of two training programmes of 6 weeks combining strength and balance exercises in different proportions. One training programme [n = 10; 71.4 (6.3) years] consisted mainly of strength exercises (ST) and the other programme [n = 8; 71.4 (6.4) years] included a majority of balance exercises (BT). Maximal strength o...

Introduction Ageing is associated with reduced strength and impaired balance, both contributing to an increased risk of falling. If few studies have reported that training programmes combining balance and strength exercises improved postural control and muscle strength (Granacher et al. 2011), the optimal proportion of both types of exercises to i...

Balance control during upright standing is accompanied by an increased amplitude of motor potentials evoked (MEP) by transcranial magnetic stimulation and a decreased amplitude of the Hoffmann (H) reflex in soleus muscle. Nonetheless, whether these observations reflect reciprocal adjustments between corticospinal and group I afferents pathways duri...

Videos of the conference are now available online! http://www.canal-insep.fr/enhancing-muscle-capacities-strength-power-velocity INSEP, the French National Institute of Sport, is proud to announce the organization of an international conference entitled "Enhancing muscle capacities: strength, power, velocity", to take place in Paris on 19-20 May 2...

The magnitude of the neural activation, and hence the force produced by a muscle, depend on the number of motor units activated (recruitment) and the rates at which motor neurons discharge action potentials (rate coding). Although the recruitment order of motor units (size principle) is similar for contractions during which the force is gradually i...

This study investigated the influence of vision and proprioception on the excitability of direct corticospinal (corticomotoneuronal) pathway to soleus in young and elderly adults during upright standing. Ten young and ten elderly adults stood upright on a rigid surface with eyes open or closed, and on foam mat with eyes open. The corticomotoneurona...

This study investigated the effects of ageing on the excitability of soleus homonymous Ia afferents and corticospinal pathways during bipedal upright standing. The input-output relations for the Hoffmann (H) reflex and motor evoked potential (MEP) were computed for the soleus in response to electrical nerve stimulation and transcranial magnetic sti...

The short-term administration of glucocorticoids increases maximal voluntary force in healthy humans but the underlying mechanisms remain poorly understood. The present study investigated the glucocorticoid effects on spinal and corticospinal pathways, and on electromechanical properties of the tibialis anterior (TA) muscle in response to nerve sti...

This study investigated the changes in muscular activity and tissue oxygenation while lifting and lowering a load of 20, 40, 60 or 80 % of one repetition maximum (1RM) with elbow flexor muscles until failure. The surface electromyogram (EMG) was recorded in biceps brachii (BB), brachioradialis (BRD) and triceps brachii (TB). For BB, a tissue oxygen...

The purpose of this brief review is to examine our current knowledge of the neural control of eccentric contractions. The review focuses on three main issues. The first issue considers the ability of individuals to activate muscles maximally during eccentric contractions. Most studies indicate that, regardless of the experimental approach (surface...

The purpose of this brief review is to synthesize the scientific knowledge related to sarcopenia (reduction in muscle mass with ageing) and the associated functional alterations. Sarcopenia is not only due to the atrophy of muscle fibres but also to a loss of fibres resulting from the apoptosis of some motor neurones in the spinal cord. These alter...

Our purpose was to compare the effect of a periodized preparation consisting of power endurance training and high-intensity power training on the contractile properties of the quadriceps muscle and functional performances in well trained male sprinters (n = 7). After 4 weeks of high-intensity power training, 60-m sprint running time improved by an...

Our purpose was to compare the effect of a periodized preparation consisting of power endurance training and high-intensity power training on the contractile properties of the quadriceps muscle and functional performances in well trained male sprinters (n = 7). After 4 weeks of high-intensity power training, 60-m sprint running time improved by an...

Key points The observed decrease in balance with ageing, vision suppression and compliance of the support surface may involve differential modulation of Ia afferent feedback from leg muscles. The modulation of Ia presynaptic inhibition for the soleus muscle was assessed in young and elderly adults when standing in normal and modified visual (eyes c...

Purpose: Prolonged exhaustive exercise induces a failure of the nervous system to activate the involved muscles maximally (i.e., central fatigue). Part of central fatigue may reflect insufficient output from the motor cortex (i.e., supraspinal fatigue), but the cause is unresolved. To investigate the potential link between supraspinal fatigue and...

This study investigated the adjustments in muscle activation and oxygenation in biceps and triceps brachii during two tasks sustained to failure at 20 and 60% of the maximal voluntary contraction (MVC) force. The tasks required participants either to push against a rigid restraint (force task) or to support an inertial load (position task) with the...

The purpose of this study was to record the discharge characteristics of tibialis anterior motor units over a range of target forces and to import these data, along with previously reported observations, into a computational model to compare experimental and simulated measures of torque variability during isometric contractions with the dorsiflexor...

Mechanical properties of the muscle-tendon unit change with aging, but it is not known how these modifications influence the control of lower leg muscles during upright stance. In this study, young and elderly adults stood upright on a force platform with and without vision while muscle architecture and myotendinous junction movements (expressed re...

An important aspect of central fatigue is supraspinal fatigue, or fatigue originating from an insufficient output from the motor cortex. One possible underlying mechanism is that this reaction is evoked by changes in brain neurotransmitters such as dopamine (DA) and noradrenaline (NA). In the present study, we looked into the relation between supra...

Soon after Edward Liddell [1895-1981] and Charles Sherrington [1857-1952] introduced the concept of a motor unit in 1925 and the necessary technology was developed, the recording of single motor unit activity became feasible in humans. It was quickly discovered by Edgar Adrian [1889-1977] and Detlev Bronk [1897-1975] that the force exerted by muscl...

The analysis of movement dates back to antiquity and by the early 20th C its study was tied closely to the properties of motoneurons, particularly those innervating limb and respi- ratory muscles. Now, in the 21st C, the analysis of movement is quite sophisticated, and motoneuron (MN) neurobiology is on the forefront of the integration of molecular...

During voluntary contractions, motor neurone activity is modulated by descending input and sensory feedback. Impaired excitatory afferent feedback with ageing may, therefore, alter motor control. This study investigated the age-related changes in afferent feedback through the recording of reflex responses during voluntary muscle activation. Short-...

This study was designed to investigate the cortical and spinal mechanisms involved in the modulations of neural activation during lengthening compared with isometric and shortening maximal voluntary contractions (MVCs). Two muscles susceptible to different neural adjustments at the spinal level, the soleus (SOL) and medial gastrocnemius (MG), were...