Caroline Nicol
Aix-Marseille University, Faculté des Sciences du Sport, Faculty Member
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Nicol C, Komi PV, Marconnet P. Fatigue effects of marathon running on neuromuscular performance. I. Changes in muscle force and stiffness characteristics. Scand J Med Sci Sports 1991: 1: 10-17. Nine experienced endurance runners performed... more
Nicol C, Komi PV, Marconnet P. Fatigue effects of marathon running on neuromuscular performance. I. Changes in muscle force and stiffness characteristics. Scand J Med Sci Sports 1991: 1: 10-17. Nine experienced endurance runners performed individual marathon runs that involved several tests of neuromuscular performance before, during and after the marathon. The tests were performed with special force platform and dynamometer techniques. The results showed an overall decrease in performance from the marathon. The maximal sprint velocity decreased parabolically during the marathon, reaching the final value of 84% of the pre-marathon one. Similarly, the other test results after marathon indicated that maximal isometric knee extension torque was 78%, the performance in a special rebound test (drop jump) 84% and the 5-jump performance 92% of the pre-marathon values. These reductions were accompanied by alteration in the ground reaction force curves in the sprint and jump tests, suggestin...
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After limb amputation, patients often wake up with a vivid perception of the presence of the missing limb, called "phantom limb". Phantom limbs have mostly been studied with respect to pain sensation. But patients can experience... more
After limb amputation, patients often wake up with a vivid perception of the presence of the missing limb, called "phantom limb". Phantom limbs have mostly been studied with respect to pain sensation. But patients can experience many other phantom sensations, including voluntary movements. The goal of the present study was to quantify phantom movement kinematics and relate these to intact limb kinematics and to the time elapsed since amputation. Six upper arm and two forearm amputees with various delays since amputation (6months to 32years) performed phantom finger, hand and wrist movements at self-chosen comfortable velocities. The kinematics of the phantom movements was indirectly obtained via the intact limb that synchronously mimicked the phantom limb movements, using a Cyberglove® for measuring finger movements and an inertial measurement unit for wrist movements. Results show that the execution of phantom movements is perceived as "natural" but effortful. T...
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Objectives: To identify relevant physiological, mechanical, and strength indices to improve the evaluation of elite mountain bike riders competing in the current Cross-Country Olympic (XCO) format. Methods: Considering the evolution of... more
Objectives: To identify relevant physiological, mechanical, and strength indices to improve the evaluation of elite mountain bike riders competing in the current Cross-Country Olympic (XCO) format. Methods: Considering the evolution of the XCO race format over the last decade, the present testing protocol adopted a battery of complementary laboratory cycling tests: a maximal aerobic consumption, a force–velocity test, and a multi-short-sprint test. A group of 33 elite-level XCO riders completed the entire testing protocol and at least 5 international competitions. Results: Very large correlations were found between the XCO performance and maximal aerobic power output (r = .78; P < .05), power at the second ventilation threshold (r = .83; P < .05), maximal pedaling force (r = .77; P < .05), and maximum power in the sixth sprint (r = .87; P < .05) of the multi-short-sprint test. A multiple regression model revealed that the normalized XCO performance was predicted at 89.2%...
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Introduction L’intervention en activite physique (AP) peut aider les adolescents obeses a sortir du cercle vicieux d’un desengagement de la pratique physique [1] . L’objectif de cette etude etait de mesurer les effets psychophysiologiques... more
Introduction L’intervention en activite physique (AP) peut aider les adolescents obeses a sortir du cercle vicieux d’un desengagement de la pratique physique [1] . L’objectif de cette etude etait de mesurer les effets psychophysiologiques d’exercices courts et intenses associes a une diete. Materiels et methodes Les effets (i) differes et (ii) immediats d’un programme sur cinq semaines de trois exercices intermittents hebdomadaires randomises de meme intensite vigoureuse (EIV) controlee (> 80 % FCmax, > 6 Kcal/min) de contextes (basketball, bike’n run, boxe pieds-poings) et de durees nettes differentes (respectivement 30, 12 et 8 min) ont ete etudies. La composition corporelle (taille, poids, % masse grasse) et les conditions physiques objectives (distance et travail au test de marche de 6 minutes [2] , frequence cardiaque, lactatemie) et percues (soi physique percu) [3] ont ete mesures aupres de 24 garcons et filles obeses (14–15 ans ; IMC = 32,64 ± 4,88 kg.m−2). Une Anova a ...
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studies dealing with body unweighing have focused on the walking pattern and showed reduced vertical ground reaction forces and longer contact time [1,2]. Little is known about the unweighing influence on the running pattern but decreases... more
studies dealing with body unweighing have focused on the walking pattern and showed reduced vertical ground reaction forces and longer contact time [1,2]. Little is known about the unweighing influence on the running pattern but decreases in loading rate, impact peak force and active peak force have been reported [3].
This study examined the combined effect of exercise induced hyperthermia and dehydration on neuromuscular function in human subjects. Six trained male runners ran for 40 min on a treadmill at 65% of their maximal aerobic velocity while... more
This study examined the combined effect of exercise induced hyperthermia and dehydration on neuromuscular function in human subjects. Six trained male runners ran for 40 min on a treadmill at 65% of their maximal aerobic velocity while wearing a tracksuit covered with an impermeable jacket and pants to impair the evaporation of sweat. These stressful experimental running conditions led the runners to a physiological status close to exhaustion. On average, the 40 min run ended at a heart rate of 196 (SD 8) beats.min-1, a tympanic temperature of 40 (SD 0.3) degrees C and with a loss of body mass of 2 (SD 0.5)%. Pre- and post-running strength tests included measurements of maximal knee extension and flexion torques in both isometric and isokinetic (at 60 and 240 degrees.s-1) conditions. A 20 s endurance test at 240 degrees.s-1 was also performed. Surface electromyographic (EMG) activity was recorded from six knee extensor and flexor muscles during the entire protocol. The treadmill run led to clear decrements in maximal extension torque and EMG activity both in isometric and at the slowest isokinetic velocity (60 degrees.s-1). However, no differences in these parameters were observed at 240 degrees.s-1. Furthermore, the EMG patterns of the major knee extensor and flexor muscles remained remarkably stable during the treadmill run. These results demonstrate that the exercise-induced hyperthermia and dehydration in the present experiments had only minor effects on the neuromuscular performance. However, it is also suggested that high internal body temperature per se could limit the production of high force levels.
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Spécialité : Sciences du mouvement Humain LE CYCLE ETIREMENT-DETENTE : un modèle d'étude des mécanismes de compensation en cas d'altération du système musculo-tendineux Mémoire de recherche présenté par Caroline Nicol Soutenue le... more
Spécialité : Sciences du mouvement Humain LE CYCLE ETIREMENT-DETENTE : un modèle d'étude des mécanismes de compensation en cas d'altération du système musculo-tendineux Mémoire de recherche présenté par Caroline Nicol Soutenue le 30 janvier 2009.Dans les formes habituelles de la locomotion, les muscles extenseurs des membres inférieurs sontengagés au cours de chaque appui au sol dans un enchaînement de phases de freinage (excentrique) etde poussée (concentrique). Cette combinaison, appelée Cycle Etirement-Détente, est connue pouraccroître l’efficacité de la phase finale concentrique, notamment par la restitution de l’énergieélastique préalablement accumulée lors de l’étirement actif du complexe musculo-tendineux. Nostravaux ont contribué à démontrer que l’intervention de la composante de courte latence du réflexed’étirement musculaire permettait d’accroître la force et la raideur du muscle. L’utilisation récente del’échographie à haute fréquence révèle l’existence d’un étire...
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In natural forms of ground locomotion such as running and jumping, the functional phases include the stretching of the preactivated muscles followed by their shortening. This is called stretch-shortening cycle (SSC). SSC is a natural but... more
In natural forms of ground locomotion such as running and jumping, the functional phases include the stretching of the preactivated muscles followed by their shortening. This is called stretch-shortening cycle (SSC). SSC is a natural but complex activity that combines the available structuro-functional resources: the contractile and elastic structures with the central and reflex activation patterns. SSC may thus be used as a model to reveal the neural adjustments and the associated muscle-tendon responses to internal and external constraints. This presentation will focus on the neuro-mechanical adjustments to the acute and delayed SSC fatigue effects and to partial unweighting on lower body positive pressure treadmill. Both testing conditions emphasize the adaptive quality of the SSC, and demonstrate Time-, Taskand SSC phase-dependent neuro-mechanical adjustments.
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An arm amputation is extremely invalidating since many of our daily tasks require bi-manual and precise control of hand movements. Perfect hand prostheses should therefore offer a natural, intuitive and cognitively simple control over... more
An arm amputation is extremely invalidating since many of our daily tasks require bi-manual and precise control of hand movements. Perfect hand prostheses should therefore offer a natural, intuitive and cognitively simple control over their numerous biomimetic active degrees of freedom. While efficient polydigital prostheses are commercially available, their control remains complex to master and offers limited possibilities, especially for high amputation levels. In this pilot study, we demonstrate the possibility for upper-arm amputees to intuitively control a polydigital hand prosthesis by using surface myoelectric activities of residual limb muscles (sEMG) associated with phantom limb movements, even if these residual arm muscles on which the phantom activity is measured were not naturally associated with hand movements before amputation. Using pattern recognition methods, three arm amputees were able, without training, to initiate 5–8 movements of a robotic hand (including indiv...
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Une amputation a comme consequence la privation soudaine d'entrees sensorielles au niveau du systeme nerveux central ainsi que la perte de cibles musculaires pour les fibres efferentes. Le systeme nerveux central, avec sa grande... more
Une amputation a comme consequence la privation soudaine d'entrees sensorielles au niveau du systeme nerveux central ainsi que la perte de cibles musculaires pour les fibres efferentes. Le systeme nerveux central, avec sa grande capacite d'adaptation, reagit a cette privation par une reorganisation anatomique et fonctionnel a differentes echelles de temps. Ce papier resume les reorganisations fonctionnelles au niveau des aires sensorimotrices primaires suite a une amputation d'un membre. Ensuite, nous abordons les mecanismes sous-jacents au membre fantome avec l'accent sur sa mobilite, peu connue mais repandue. Nous finissons avec l'interet que peut avoir la mobilite du membre fantome pour la readaptation de patients amputes du membre superieur.
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This study investigated the sex influence on the acute and delayed fatigue effects of a 20 km graded running race. Eighteen recreational runners, 10 women and 8 men, completed the race. The testing protocol included five sessions: a week... more
This study investigated the sex influence on the acute and delayed fatigue effects of a 20 km graded running race. Eighteen recreational runners, 10 women and 8 men, completed the race. The testing protocol included five sessions: a week before the race (PRE), 35 ± 15 min after (POST), 2 h, 2 and 4 days (2D and 4D) later. Each session included uni- and bilateral maximal isometric voluntary contractions of the knee extensors (MVC), a squat jump (SJ), and a drop jump (DJ). Acute and delayed muscle soreness (DOMS) were evaluated for the quadriceps, hamstring and triceps surae muscle groups. The 2D and 4D sessions included also a horizontal force-velocity test (HF-V) performed under five resistive conditions. For each test, a set of key variables was computed to characterize the lower limb functional recovery. Mixed ANOVA analyses revealed significant (sex × time) interactions, with larger acute drops for men in MVCs and earlier recovery for women in the bilateral MVC (p < 0.001) and...
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Specialite : Sciences du mouvement Humain LE CYCLE ETIREMENT-DETENTE : un modele d'etude des mecanismes de compensation en cas d'alteration du systeme musculo-tendineux Memoire de recherche presente par Caroline Nicol Soutenue le... more
Specialite : Sciences du mouvement Humain LE CYCLE ETIREMENT-DETENTE : un modele d'etude des mecanismes de compensation en cas d'alteration du systeme musculo-tendineux Memoire de recherche presente par Caroline Nicol Soutenue le 30 janvier 2009. Dans les formes habituelles de la locomotion, les muscles extenseurs des membres inferieurs sont engages au cours de chaque appui au sol dans un enchainement de phases de freinage (excentrique) et de poussee (concentrique). Cette combinaison, appelee Cycle Etirement-Detente, est connue pour accroitre l’efficacite de la phase finale concentrique, notamment par la restitution de l’energie elastique prealablement accumulee lors de l’etirement actif du complexe musculo-tendineux. Nos travaux ont contribue a demontrer que l’intervention de la composante de courte latence du reflexe d’etirement musculaire permettait d’accroitre la force et la raideur du muscle. L’utilisation recente de l’echographie a haute frequence revele l’existence d’...
Among the running field tests that measure aerobic fitness indirectly, the 20-m shuttle run test is the one most commonly used among obese youth. However, this back and forth running test induces premature cessation of exercise in this... more
Among the running field tests that measure aerobic fitness indirectly, the 20-m shuttle run test is the one most commonly used among obese youth. However, this back and forth running test induces premature cessation of exercise in this population. The present study aimed to examine the psycho-physiological responses of obese adolescents to an intermittent (15-15) progressive and maximal run test as compared with a continuous shuttle run test. Eleven obese adolescents (age: 14-15 years; BMI = 34.01 ± 5.30 kg·m-2) performed both tests. A two-way ANOVA examined the main effects of the running test, participant's sex, and their interaction on maximal aerobic performance (net exercise duration and final velocity), physiological values (heart rate, pulmonary oxygen uptake, respiratory exchange ratio and blood lactate concentration) and psychological responses (rating of perceived exertion, and physical self-perceptions). Oxygen uptake and heart-rate values at 9 km·h-1 were also compar...
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Introduction/Background In the light of the development of polydigital hand prosthesis, we recently explored an intuitive control mode by surface EMG associated to phantom limb movements (PLM) in upper arm amputees (Jarrasse et al.,... more
Introduction/Background In the light of the development of polydigital hand prosthesis, we recently explored an intuitive control mode by surface EMG associated to phantom limb movements (PLM) in upper arm amputees (Jarrasse et al., 2017a, b). As little was known about PLM, we described types and characteristics of upper limb PLM and explored some factors potentially influencing these in a population of upper limb amputees (De Graaf et al., 2016; Touillet et al., submitted). We showed, among others, that one persistent characteristic of PLM is the associated fatigue, which potentially is a problem when using PLM for prosthesis control since fatigue diminish the mobilization capacity as well as the stability of the EMG signals and thus interferes with the prosthesis control. Material and method In the present study, we explored whether PLM training (not to confound with learning) can increase mobilization capacity and stabilize EMG signals. Five trans-humeral amputees volunteered for training of all their types of PLM at home on a daily basis during about 6 weeks. Kinematics (via the intact limb imitating the phantom movements) as well as EMG signals from the residual muscles were recorded just before and right after the training period. Results None of the participants experienced (phantom or residual limb) pain related to the training. Three participants increased the number of different PLM they could execute. All of them increased the amplitude and velocity, and thus diminished the cycle duration, as well as the number of cycles they could execute before the PLM blocked by fatigue. The amplitude of the EMG increased and became more specific to the type of PLM. Conclusion In conclusion, as is the case for intact limbs, training of PLM improves motor performance and stabilizes the EMG signals associated to PLM execution. This is encouraging for future PLM-based prosthesis control.
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Objective The lower body positive pressure (LBPP) treadmill is emerging as an innovative tool for rehabilitation as it allows running in partial unweighted conditions. This technology uses small increase in air pressure to produce a... more
Objective The lower body positive pressure (LBPP) treadmill is emerging as an innovative tool for rehabilitation as it allows running in partial unweighted conditions. This technology uses small increase in air pressure to produce a lifting force via an airtight chamber applied to the runner's pelvis, leading to a substantial bodyweight (BW) reduction while the lower limbs still experience normogravity. An appropriate use of LBPP treadmill requires an improved understanding of the associated neural and mechanical adjustments of the running pattern. Material/patients and methods Twenty healthy males performed 2 randomized runs of 9 min at preferred speed on an LBPP treadmill. Each series included 3 successive running conditions of 3 min at preferred speed (at 100%, 60 or 80%, and 100% BW) with progressive transitions in between. Vertical ground reaction forces (Fz) were recorded together with surface electromyographic (EMG) activity from 6 muscles of the left lower limb. The analyses were performed on the stabilized running pattern in each condition and on the progressive changes along the transitions. Results Unweighting resulted in a rebounding running pattern (increased flight and unchanged contact time) and in a shift from a heel to a midfoot striking pattern. This latter modification was still observed after reloading. The transition analyses highlighted the linearity between the BW and the Fz changes, whereas the activation pattern showed adjustments which were muscle- and stride phase-dependent. Unweighting did not affect the extensor muscle preactivation, led to parallel decreases in quadriceps activation and Fz during the braking phase, and to reduced triceps surae activation during the push-off phase. Almost all changes were mirrored during reloading. Discussion – conclusion The results confirm the linearity between the BW changes and the vertical mechanical loading of the lower limb. For clinical purpose, our results highlight the need to further examine the LBPP-induced neuromechanical changes. The EMG stability during the preactivation phase suggests a preserved preparation for ground impact. Yet, eventual adaptation should be explored by protocols using repeated treadmill running sessions. The adoption of a midfoot striking pattern with a reduced quadriceps activation during the braking phase might be beneficial for specific clinical cases.