10 research outputs found
Online Yoga-Based and Standard Exercises for Patients with a Rotator Cuff Injury Awaiting Surgery: A Feasibility Study
This study investigates the feasibility of conducting a 6-week intervention program comparing online yoga-based and standard exercises among 10 injured pre-surgery rotator cuff patients. Case reports on two patients are presented to demonstrate implementation and potential consequences of both interventions. A feasibility study was conducted after recruiting 10 patients from surgical wait list of 51 patients. Patients in both studies were assessed for shoulder flexion, abduction and external rotation range of motion and strength at aseline and 6- weeks. The SPADI questionnaire was used to assess pain/function. Most (8/10) patients in the feasibility study did not complete the full protocol. One caseworsened (yoga), while another (standard exercise) improved in strength. This does not indicate relative efficacy. SPADI results were changed by less than 10%indicating no clinically important change. Qualitative feedback suggested that patients might be open to online exercises. Developmental work is needed to define a easible intervention/study design
The Effect of McConnell Shoulder Taping on Shoulder Muscle EMG and Shoulder Torque Productions in Subjects With Anterior Shoulder Instability
Introduction: Anterior shoulder instability (ASI), a common clinical problem, causes significant functional impairments. Despite little evidence to support its use, rehabilitation directed at the unstable glenohumeral joint often includes McConnell shoulder taping. This taping technique consists of a base layer of tape followed by application of a rigid strapping tape (corrective) to restrain excessive translation of the humeral head. The aims of this study were to determine the effects of McConnell shoulder taping on EMG amplitude of ten shoulder muscles and on shoulder joint peak torque between three conditions: no tape and base tape alone; no tape and McConnell tape (base plus corrective) and between base tape alone and McConnell tape during isokinetic scaption and external rotation at two abduction positions in subjects with ASI.
Methods: Eleven subjects with ASI completed concentric isokinetic testing in three functional exercise movement patterns while wearing a combination of fine wire and surface electrodes. Peak EMG amplitude for three phases of each movement pattern and peak isokinetic shoulder joint torque were evaluated. The absolute values of the change scores between the three tape conditions were analyzed using t tests (p\u3c.0166).
Results: Changes in EMG activity between each of the taping conditions increased in some subjects and decreased in others. On the whole, significant differences in EMG amplitude occurred after application of full McConnell taping as well as after application of base tape alone for the rotator cuff and deltoid muscles in all three movement patterns. The remaining six muscles demonstrated significant changes in EMG amplitude over selective arcs of motion in some movement patterns, although findings were less consistent. No significant differences in shoulder joint peak torque for any of the taping conditions arose.
Discussion: McConnell taping effects a change in EMG activity for most shoulder muscles but not on peak torque in subjects with ASI. Similarly, the base tape alone can also cause a change in EMG activity. This suggests a possible sensory effect from tape on the skin.
Conclusion: This study supports the use of McConnell shoulder taping as a means for influencing neuromuscular activity during a shoulder rehabilitation program for persons with ASI
Interdisciplinary methodological framework of biomechanics and occupational psychology for MSD prevention
In France and globally, musculoskeletal disorders (MSD) remain the most widespread occupational diseases. The scientific literature has established that links exist between occurrence of MSD and the professional gesture. The aim of this paper is to analyse how an intervention was conducted within the general methodological framework of occupational psychology using activity clinical research based on professional gesture analysis and it has enjoyed interdisciplinary co-operation with biomechanics. The interdisciplinary methodology implemented with eight gravediggers was based on different steps including a detailed analysis of the muscular activity of the shoulder and back muscles. The results show that the presented methodology allows opening more widely the potential development zone of the gesture in the gravediggers' activity by stimulating their professional discussions. The visibility and discussion in the profession of inter- and intra-individual variability has opened up the professional world to new forms of MSD prevention actions.En France et à l’international, les troubles musculo-squelettiques (TMS) restent les maladies professionnelles les plus répandues. La littérature scientifique a établi l’existence de liens entre la survenue des TMS et la réalisation des gestes en situation de travail. L’objectif de cet article est de montrer comment l’analyse biomécanique participe à la création d’outils d’intervention mis en œuvre dans un cadre méthodologique en clinique de l’activité dans une optique de prévention des TMS se basant sur l’analyse du geste. La méthodologie interdisciplinaire mise en œuvre auprès de huit fossoyeurs comprend plusieurs étapes incluant une analyse de l’activité musculaire des muscles de l’épaule et du dos laquelle est utilisée comme support à des autoconfrontations. Les résultats montrent que la méthodologie interdisciplinaire permet d’ouvrir plus largement la zone de développement potentiel du geste dans l’activité des fossoyeurs en stimulant leurs discussions professionnelles. La mise en visibilité et en discussion dans le métier de la variabilité inter et intra-individuelle de réalisation d’un même geste au contact des questions concrètes de travail a ouvert le milieu professionnel vers de nouvelles formes d’actions de prévention des TMS dans l’organisation prescrite du travail
Avaliação do nĂvel de esforço muscular durante diferentes estratĂ©gias de levantar-se de uma posição sentada
A análise do movimento de levantar-se exige o conhecimento de fatores que influenciam na sua realização, sendo que os fatores relacionados Ă estratĂ©gia sĂŁo aqueles oriundos da execução do movimento. A cinemática básica do movimento de levantar-se indica que antes da retirada dos glĂşteos do assento o movimento do quadril Ă© predominante ao movimento da coluna lombar, com uma proporção quadril – coluna lombar de 3:1. Considerando o resultado de um modelo matemático, o esforço gerado na coluna lombar foi maior quando a tarefa de levantar-se foi executada com a proporção considerada correta. Dessa forma, o objetivo geral desse estudo foi verificar a relação do nĂvel de esforço avaliado a partir de uma resposta mecânica, estimada por um macromodelo biomecânico tridimensonal, entre o nĂvel de esforço avaliado pela eletromiogrfia dos mĂşsculos iliocostal, longuĂssimo e multĂfido da regiĂŁo lombar e a percepção subjetiva de esforço (escala de Borg), durante diferentes estratĂ©gias cinemáticas e musculares de realizar a tarefa de levantar-se. Para isso, 20 participantes do sexo feminino executaram a tarefa de levantar-se usando duas diferentes estratĂ©gias cinemáticas e duas diferentes estratĂ©gias musculares, enquanto que dados cinemáticos, eletromiográficos e de percepção subjetiva de esforço foram coletados. O coeficiente de Correlação de Person foi utilizado para avaliar a correlação entre os diferentes parâmetros de medida. Foi encontrada uma correlação alta e positiva entre a força muscular resultante e a ativação muscular para cada uma das diferentes estratĂ©gias cinemáticas e musculares, enquanto que houve uma discordância entre os achados de força muscular resultante e a percepção subjetiva de esforço.The rising movement demands a basic knowledge of factors influencing its achievement, and the factors related to the strategy are those derived from the execution of the movement. The rising movement’s basic kinematics indicates that before removing the gluteus from the seat hip movement is predominant to lumbar column movement, with hip/lumbar column proportion of 3:1. Considering the results of a mathematical model, the effort generated in the lumbar column was higher when the rising task was executed with the proportion considered correct. Thus, general objective of this study was to verify the relationship of the effort level assessed from a mechanical response, estimated by a tridimensional biomechanical macromodel, between the effort level evaluated by electromyography of the muscles iliocostalis, longissimus and multifidus of the lumbar region and perceived exertion (Borg scale), during different kinematics and muscular strategies for achievement the rising task. Twenty female participants performed the rising task using two different kinematics strategies and two different muscular strategies, while kinematics, electromyographic and perceived exertion data were collected. Pearson correlation coefficient was used for assessing the correlation between different measuring parameters. A high and positive correlation between resultant muscle force and muscle activation was found for each of the different kinematic and muscular strategies, while there was a disagreement between the findings of resultant muscle force and perceived exertion
Proposition de combinaisons optimales de contractions volontaires maximales isométriques pour la normalisation de 12 muscles de l'épaule
Afin d’être représentatif d’un niveau d’effort musculaire, le signal électromyographique
(EMG) est exprimé par rapport à une valeur d’activation maximale. Comme l’épaule est
une structure articulaire et musculaire complexe, aucune contraction volontaire isométrique
(CVMi) proposée dans la littérature ne permet d’activer maximalement un même
muscle de l’épaule pour un groupe d’individus. L’objectif de ce mémoire est de développer
une approche statistique permettant de déterminer les CVMi optimales afin de maximiser
les niveaux d’activation d’un ensemble de muscles de l’épaule.
L’amplitude du signal EMG de 12 muscles de l’épaule a été enregistrée chez 16 sujets
alors qu’ils effectuaient 15 CVMi. Une première approche systématique a permis de
déterminer les 4 CVMi parmi les 15 qui ensemble maximisent les niveaux d’activation
pour les 12 muscles simultanément. Ces 4 contractions ont donné des niveaux d’activation
supérieurs aux recommandations antérieures pour 4 muscles de l’épaule. Une seconde approche
a permis de déterminer le nombre minimal de CVMi qui sont nécessaires afin de
produire un niveau d’activation qui n’est pas significativement différent des valeurs d’activation
maximales pour les 16 sujets. Pour 12 muscles de l’épaule, un total de 9 CVMi
sont requises afin de produire des valeurs d’activation qui sont représentatives de l’effort
maximal de tous les sujets.
Ce mémoire a proposé deux approches originales, dont la première a maximisé les
niveaux d’activation qui peuvent être produits à partir d’un nombre fixe de CVMi tandis
que la deuxième a permis d’identifier le nombre minimal de CVMi nécessaire afin de
produire des niveaux d’activation qui ne sont pas significativement différentes des valeurs
d’activation maximales. Ces deux approches ont permis d’émettre des recommandations
concernant les CVMi nécessaires à la normalisation de l’EMG afin de réduire les risques
de sous-estimer l’effort maximal d’un ensemble d’individus.As a means to provide information on the intensity of the muscle activity, the electromyographic
(EMG) signal must be expressed as a percentage of a maximum activation
value. Because of the anatomical complexity of the shoulder, no single maximum voluntary
isometric contraction (MVIC) has been found to maximally activate the same muscle for
a group of subjects. The objective of this study is to develop a statistical approach to
determine the optimal MVICs that can maximise the activation levels for several shoulder
muscles.
The amplitude of the EMG signal of 12 shoulder muscles was recorded as 16 subjects
performed 15 MVICs in standardised positions. A first systematic approach was used to
determine the optimal 4 MVICs amongst 15 that could maximise the activation levels
of 12 shoulder muscles simultaneously. The activation levels produced by these 4 MVICs
were significantly higher than those produced by previous recommendations. A second
approach was adopted to identify the minimum number of MVICs that were required
to produce muscle activation levels that did not significantly differ from the maximum
activation values. For 12 shoulder muscles, 9 MVICs were necessary to produce muscle
activation levels that were representative of the maximum effort of all 16 subjects.
This study proposed two novel approaches, the first of which maximised the EMG
activation levels that can be produced by a fixed number of MVICs while the second
approach identified the minimum number of MVICs required to produce EMG activation
levels that were not significantly different from the maximum values of activation. These
two approaches provided guidelines with regards to the MVICs that are necessary to
normalize the EMG signals of 12 shoulder muscles while reducing the risks of underestimating
the maximum capacity of each individual
Investigation of Hand Forces, Shoulder and Trunk Muscle Activation Patterns and EMG/force Ratios in Push and Pull Exertions
When designing work tasks, one goal should be to enable postures that maximize the force capabilities of the workers while minimizing the overall muscular demands; however, little is known regarding specific shoulder tissue loads during pushing and pulling. This study quantitatively evaluated the effects of direction (anterior-posterior pushing and pulling), handle height (100 cm and 150 cm), handle orientation (vertical and horizontal), included elbow angle (extended and flexed) as well as personal factors (gender, mass and stature) on hand force magnitudes, shoulder and L5/S1 joint moments, normalized mean muscle activation and electromyography (EMG)/force ratios during two-handed maximal push and pull exertions. Twelve female and twelve male volunteers performed maximal voluntary isometric contractions under 10 push and pull experimental conditions that emulated industrial tasks. Hand force magnitudes, kinematic data and bilateral EMG of seven superficial shoulder and trunk muscles were collected. Results showed that direction had the greatest influence on dependent measures. Push exertions produced the greatest forces while also reducing L5/S1 extensor moments, shoulder moments with the 150 cm height and overall muscular demands (p < 0.0001). The 100 cm handle height generated the greatest forces (p < 0.0001) and reduced muscular demands (p < 0.05), but were associated with greater sagittal plane moments (p < 0.05). Females generated, on average, 67% of male forces in addition to incurring greater muscular demands (p < 0.05). The flexed elbows condition in conjunction with pushing produced greater forces with reduced overall muscular demands (p < 0.0001). Furthermore, horizontal handle orientation caused greater resultant moments at all joints (p <. 0.05) The results have important ergonomics implications for evaluating, designing or modifying workstations, tasks or equipment towards improved task performance and the prevention of musculoskeletal injuries and associated health care costs
Implicación de la columna cervical en el dolor musculoesquelético de hombro.
Antecedentes: el dolor de hombro es la tercera causa más frecuente de trastornos musculoesquelĂ©ticos, y su diagnĂłstico sigue siendo un reto para los fisioterapeutas ya que no existe homogeneidad en los criterios clĂnicos utilizados. Objetivos: cuantificar la prevalencia de la implicaciĂłn cervical en el dolor de hombro musculoesquelĂ©tico, definida como un empeoramiento o un alivio de los sĂntomas con la exploraciĂłn cervical en valores igual o mayor al 30% de modificaciĂłn del dolor. Observar la modificaciĂłn y reproducciĂłn de sĂntomas en el hombro tras una exploraciĂłn cervical. Analizar si la implicaciĂłn cervical puede coexistir con otros diagnĂłsticos de hombro o incluso ser considerado como un Ăşnico diagnĂłstico. MĂ©todos: se cuantificĂł el dolor en la Numeric Pain Rating Scale, la funciĂłn autorreportada del hombro con el Shoulder Pain and Disability Index en su versiĂłn en castellano, la fuerza isomĂ©trica del hombro (dinamometrĂa), la movilidad del hombro (goniometrĂa mediante inclinĂłmetro) y de la columna cervical (goniometrĂa mediante el aparato Cervical Range of Motion Measurement Device), y la extensiĂłn de los sĂntomas (body chart). Tras la respuesta a la exploraciĂłn cervical, se realizĂł un diagnĂłstico del dolor de hombro basado en la subclasificaciĂłn en la que se contemplaron entidades clĂnicas como la implicaciĂłn cervical, el dolor acromioclavicular, el hombro rĂgido, el hombro inestable, el dolor relacionado con el manguito rotador y un subgrupo donde encuadrar a los sujetos que no encajaban en los diagnĂłsticos anteriores (“Otros”). Resultados: 60 sujetos fueron examinados entre febrero de 2020 y junio de 2022. Se mostrĂł una prevalencia del 50% (IC95% 37,35-62,65%) de la implicaciĂłn cervical en los sujetos estudiados, mostrando el 60% de ellos tambiĂ©n una reproducciĂłn de sĂntomas. Se encontraron cambios estadĂstica y clĂnicamente significativos en los sujetos con implicaciĂłn cervical en el dolor (p<0,001), y estadĂsticamente significativos en la flexiĂłn (p<0,001) y la abducciĂłn (p<0,001), la rotaciĂłn interna (p=0,02) y la rotaciĂłn externa a 0Âş de abducciĂłn (p=0,008) de hombro, y en la extensiĂłn (p=0,018) y la lateroflexiĂłn derecha (p=0,005) cervical entre situaciones pre y post exploraciĂłn cervical. Para los cambios mencionados, el tamaño del efecto fue grande para el dolor (r=0.62) y para la flexiĂłn y abducciĂłn de hombro (r=0.55), y moderado para la rotaciĂłn externa a 0Âş de abducciĂłn de hombro, (0.34) la rotaciĂłn interna de hombro (p=0.30), la extensiĂłn cervical (0.31) y la lateroflexiĂłn derecha cervical (0.36). La presencia de centralizaciĂłn tuvo una asociaciĂłn estadĂsticamente significativa con el diagnĂłstico de implicaciĂłn cervical (p=0,002), al igual que la presencia de dolor cervical previo (p=0,007), el diagnĂłstico de dolor relacionado con el manguito rotador (p=0,002), el sexo femenino (p=0,037), la altura (p=0,010) y el peso (p=0,002). El diagnĂłstico de dolor relacionado con el manguito rotador fue el subgrupo más prevalente (46,7% de todos los sujetos), de los cuales el 71,4% presentĂł implicaciĂłn cervical. Conclusiones: la implicaciĂłn cervical es un fenĂłmeno prevalente en el dolor musculoesquelĂ©tico del hombro donde los sujetos experimentan principalmente modificaciĂłn de sĂntomas. Además, puede coexistir con otros diagnĂłsticos o incluso considerarse como un diagnĂłstico Ăşnico en sĂ mismo
Modifications in Early Rehabilitation Protocol after Rotator Cuff Repair : EMG Studies
La déchirure de la coiffe des rotateurs est une des causes les plus fréquentes de douleur
et de dysfonctionnement de l'épaule. La réparation chirurgicale est couramment réalisée chez
les patients symptomatiques et de nombreux efforts ont été faits pour améliorer les techniques
chirurgicales. Cependant, le taux de re-déchirure est encore élevé ce qui affecte les stratégies de
réhabilitation post-opératoire. Les recommandations post-chirurgicales doivent trouver un
équilibre optimal entre le repos total afin de protéger le tendon réparé et les activités préconisées
afin de restaurer l'amplitude articulaire et la force musculaire. Après une réparation de la coiffe,
l'épaule est le plus souvent immobilisée grâce à une écharpe ou une orthèse. Cependant, cette
immobilisation limite aussi la mobilité du coude et du poignet. Cette période qui peut durer de
4 à 6 semaines où seuls des mouvements passifs peuvent être réalisés. Ensuite, les patients sont
incités à réaliser les exercices actifs assistés et des exercices actifs dans toute la mobilité
articulaire pour récupérer respectivement l’amplitude complète de mouvement actif et se
préparer aux exercices de résistance réalisés dans la phase suivante de la réadaptation. L’analyse
Ă©lectromyographique des muscles de l'Ă©paule a fourni des Ă©vidences scientifiques pour la
recommandation de beaucoup d'exercices de réadaptation au cours de cette période. Les activités
sollicitant les muscles de la coiffe des rotateurs Ă moins de 20% de leur activation maximale
volontaire sont considérés sécuritaires pour les premières phases de la réhabilitation. À partir de
ce concept, l'objectif de cette thèse a été d'évaluer des activités musculaires de l'épaule pendant
des mouvements et exercices qui peuvent théoriquement être effectués au cours des premières
phases de la réhabilitation. Les trois questions principales de cette thèse sont : 1) Est-ce que la
mobilisation du coude et du poignet produisent une grande activité des muscles de la coiffe? 2)
Est-ce que les exercices de renforcement musculaire du bras, de l’avant-bras et du torse
produisent une grande activité dans les muscles de la coiffe? 3) Au cours d'élévations actives du
bras, est-ce que le plan d'élévation affecte l'activité de la coiffe des rotateurs?
Dans notre première étude, nous avons évalué 15 muscles de l'épaule chez 14 sujets sains
par électromyographie de surface et intramusculaire. Nos résultats ont montré qu’avec une
orthèse d’épaule, les mouvements du coude et du poignet et même quelques exercices de
renforcement impliquant ces deux articulations, activent de manière sécuritaire les muscles de
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la coiffe. Nous avons également introduit des tâches de la vie quotidienne qui peuvent être
effectuĂ©es en toute sĂ©curitĂ© pendant la pĂ©riode d'immobilisation. Ces rĂ©sultats peuvent aider Ă
modifier la conception d'orthèses de l’épaule. Dans notre deuxième étude, nous avons montré
que l'adduction du bras réalisée contre une mousse à faible densité, positionnée pour remplacer
le triangle d’une orthèse, produit des activations des muscles de la coiffe sécuritaires. Dans notre
troisième étude, nous avons évalué l'électromyographie des muscles de l’épaule pendant les
tâches d'élévation du bras chez 8 patients symptomatiques avec la déchirure de coiffe des
rotateurs. Nous avons constaté que l'activité du supra-épineux était significativement plus élevée
pendant l’abduction que pendant la scaption et la flexion. Ce résultat suggère une séquence de
plan d’élévation active pendant la rééducation.
Les résultats présentés dans cette thèse, suggèrent quelques modifications dans les
protocoles de réadaptation de l’épaule pendant les 12 premières semaines après la réparation de
la coiffe. Ces suggestions fournissent Ă©galement des Ă©vidences scientifiques pour la production
d'orthèses plus dynamiques et fonctionnelles à l’articulation de l’épaule.Rotator cuff tear is one of the most common causes of shoulder pain and dysfunction. The operative repair has been widely performed for symptomatic patients and many efforts have been done to improve the surgical techniques. However, the re-tear rate is still high and this affects post-repair rehabilitation strategies. Post-surgical care should balance between the restriction imposed to protect the repaired tendon and the activities prescribed to restore range of motion and muscle strength. Frequently, early after rotator cuff repair, shoulder is immobilized in a sling or abduction orthosis, but this immobilization includes elbow and wrist joints as well. In this period that may last 4-6 weeks, only passive range of motion exercises are performed. After removing the immobilizer, patients are encouraged to do active assisted and active range of motion exercises respectively to regain the full active range of motion and be prepared for the resistance exercises in the following phase of rehabilitation. Electromyography of shoulder muscles has provided scientific basis for many of rehabilitation exercises during this period. Anecdotally, the activities of less than 20% of the maximal voluntary contraction of rotator cuff muscles are considered safe for the first phases of rehabilitation after rotator cuff repair. Using this concept, the aim of this dissertation is to evaluate the activity of shoulder musculature during some movements and exercises that can theoretically be performed during the early phases of rehabilitation. Three main questions of this thesis are: 1) Do elbow and wrist mobilizations highly activate rotator cuff muscles? 2) Do some resistance exercises of arm, forearm and chest muscles produce high activity in rotator cuff muscles? 3) During active arm elevation, does the plane of elevation affect rotator cuff activity?
In our first study, we evaluated 15 shoulder muscles in 14 healthy subjects with both surface and indwelling EMG. Our results showed that while wearing a shoulder orthosis, elbow and wrist movements and even some resistance training involving these two joints, would minimally activate the rotator cuff muscles and can be considered safe. We also introduced some daily living tasks that can be performed safely during immobilization period. These findings may help to modify the design of current shoulder orthoses. In the second study, we also showed that resisted arm adduction against a low-density foam that replaced the hard wedge of orthosis would not highly activate the cuff muscles. In our final study, we evaluated the EMG of shoulder musculature during arm elevation tasks in 8 symptomatic patients with rotator cuff tears. We found that supraspinatus activity during arm elevation is significantly higher in abduction plane than in scaption and flexion planes in patients with rotator cuff tears. This suggested a plane sequences for active range of motion exercises during rehabilitation.
The findings that are presented in this dissertation, suggest some modifications in the rehabilitation protocols during the first 12 weeks after rotator cuff repair. These suggestions also provide a scientific basis for producing more dynamic and functional shoulder orthoses
Apport de l’électromyographie de surface en tennis : proposition d’une nouvelle méthode de normalisation des muscles du membre supérieur : influence de la vitesse et de la fatigue sur l’activité musculaire du membre supérieur en tennis
The main purpose of this thesis is the study of upper limb muscle activity through surface electromyography (EMG) during a dynamic activity. An initial study showed that seven out of nine muscles can be normalized from two maximum dynamic tasks, while two other muscles require the traditional isometric method. This procedure helps to improve the reliability of the upper limb EMG while reducing the time of standardization. On the other hand, the study of the relationship between EMG and stroke velocity in forehand drive in tennis emphasized the changes in EMG amplitude and activation timing of some muscles in response to the increase of the ball velocity. Otherwise, a third study showed that fatigue generated by intense exercise tennis results in a decrease in activation level of the pectoralis major and the forearm muscles during strokes, without any change in activation timing. This decrease in EMG activity could explain the performance degradation observed during this experiment. However, strategies of organism protection and/or gestion of the speed-accuracy trade-off should be considered and may need future studiesL'objet principal de cette thèse est l'étude de l'activité musculaire du membre supérieur par le biais de l'électromyographie de surface (EMG) lors d'une activité dynamique. Une première étude a montré que sept muscles sur neuf peuvent être normalisés à partir de deux tâches maximales dynamiques, tandis que deux autres muscles doivent l'être avec la méthode traditionnelle isométrique. Cette procédure contribue à l'amélioration de la fiabilité de l'étude du membre supérieur tout en réduisant le temps de normalisation. D'autre part, l'étude de la relation entre activité EMG et vitesse de frappe en coup droit a permis de mettre en lumière les modifications d'amplitude EMG et des paramètres temporels d'activation de certains muscles du membre supérieur en réponse à l'augmentation de la vitesse de balle. Par ailleurs, une troisième étude a démontré que la fatigue générée par un exercice intense de tennis entraîne une baisse du niveau d'activation du grand pectoral et des muscles de l'avant-bras lors des frappes, sans toutefois entraîner de changement au niveau du timing d'activation. Cette diminution de l'activité EMG pourrait expliquer la dégradation de la performance relevée lors de cette expérience. Toutefois, des stratégies de protection de l'organisme et/ou de gestion du conflit vitesse-précision sont à envisager et ouvrent la voie à de futures étude