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 3.3 m/s) or while carrying three different loads (4.5, 9.1, 13.6 kg) at 2.6 m/s while kinematics and kinetics were synchronously recorded. The major lower limb muscle forces were estimated using a musculoskeletal model. Muscle force amplitudes and variability, as well as coordination patterns were compared at the group and at the individual level using respectively statistical parametric mapping and covariance matrices combined with multidimensional scaling. Increasing the speed or the load during running increased most of the muscle force amplitudes (p < 0.01). During the propulsion phase, increasing the load increased muscle force variabilities around the ankle joint (modification of standard deviation up to 5% of body weight (BW), p < 0.05) while increasing the speed decreased variability for almost all the muscle forces (up to 10% of BW, p < 0.05). Each runner has a specific muscle force coordination pattern signature regardless of the different experimental conditions (p < 0.05). Yet, this individual pattern was slightly adapted in response to a change of speed or load (p < 0.05). Our results suggest that adding load increases the amplitude and variability of muscle force, but an increase in running speed decreases the variability. These findings may help improve the design of military or trail running training programs and injury rehabilitation by progressively increasing the mechanical load on anatomical structures.

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. 18 participants performed maximal isometric finger force production during pinch grip (Pinch) and four-finger pressing (Press) tasks in four different wrist postures (extended, flexed, neutral, spontaneous). The maximum finger force (MFF), finger and wrist joint angles, as well as activation of four muscles were determined using dynamometry, motion capture, and electromyography. The force and length of the four muscles were estimated from joint angles and muscle activation using a musculoskeletal model. MFF decreased for flexed wrist during Pinch but remained stable across wrist postures during Press. The results suggested that the loss of pinch grip force in deviated wrist posture is partially related to force-length relationship of finger extensors. In opposition, MFF during Press was not influenced by the modulation of muscle capacities but was probably first limited by mechanical and neural factors related to finger interdependence.

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

BACKGROUND/PURPOSE: 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. Incremental exercises and sensorimotor tests were performed at day 1 (D1), D8, and D15 after tMCAO. Molecular analyses were achieved in both the paretic and non-paretic triceps brachii muscles and the ipsi- and contralesional cortices at D17 RESULTS: Gains in endurance performance are in a time-dependent manner from the first week of training. This enhancement is supported by the upregulation of metabolic markers in both triceps brachii muscles. Both regimens alter the expression of neurotrophic markers and chloride homeostasis in a specific manner in the ipsi- and contralesional cortices. HIIT acts on apoptosis markers by promoting anti-apoptotic proteins in the ipsilesional cortex CONCLUSION: HIIT regimens seem to be of clinical relevance in the critical period of stroke rehabilitation by strongly improving aerobic performance. Also, the observed cortical changes suggest an influence of HIIT on neuroplasticity in both ipsi- and contralesional hemispheres. Such neurotrophic markers might be considered as biomarkers of functional recovery in individuals with stroke.

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

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). Participants trained on a 12 mm-deep hold, twice a week for 4 weeks. The MFS, stamina, and endurance levels were evaluated using force data before and after training. Results showed similar values in the control group between pre- and post-tests. A significantly improved MFS was observed in the F100 and F80 groups but not in the F60 group. Significantly higher stamina and endurance measurements were observed in the F80 and F60 groups but not in the F100 group. These results showed that a 4-week hangboard training enabled increasing MFS, stamina and endurance, and that different improvements occurred according to the level of training intensity. Interestingly, the different intensities allow improvements in the targeted capacity (e.g., stamina for the F80 group) but also in the adjacent physiological capabilities (e.g., MFS for the F80 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. A 3D dynamic finite element foot model driven by extrinsic muscle forces was developed to estimate the stress undergone by the different internal foot structures during the stance phase. The boundary conditions of different trials with similar running speed were used as input. Variability in bone stress (10%) and cartilage pressure (16%) can be expected while keeping the overall running speed constant. Bone and cartilage stress were mainly influenced by the muscle force profiles rather than by ground reaction force. These findings suggest, first, that the analysis of a single trial only is not representative of the internal tissue loadings distribution in the foot and second, that muscle forces must be considered when estimating bone and cartilage loadings at the foot level. This model could be applied to an optimal clinical management of the overuse injury.

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. In parallel, cortical markers related to neurotrophic, angiogenic, and metabolic activities were assessed. Results indicate that HIIT induced an early and superior endurance improvement compared to MICT. We found significant enhancement of speed associated with lactate threshold (SLT) and maximal speed (Smax) in HIIT animals. MICT promoted an early increase in brain-derived neurotrophic factor and angiogenic/metabolic markers but showed less influence at 8 weeks. HIIT upregulated the insulin-like growth factor-1 (IGF-1) as well as neurotrophic, metabolic/angiogenic markers at 2 and 8 weeks and downregulated the neuronal K-Cl cotransporter KCC2 that regulates GABAA-mediated transmission. HIIT and MICT are effective in a time-dependent manner suggesting a complementary effect that might be useful in physical exercise guidelines for maintaining brain health.

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. This study demonstrates that it can be used as a reliable anatomic landmark when performing an injection for both regional anesthesia and in the treatment of saphenous nerve tunnel syndrome.

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. The various methodological limitations related to the clinical relevance of studies on the exercise recommendations in individuals with stroke are first discussed. Then, the relevance of HIIT in improving neurotrophic factors expression, neurogenesis and synaptic plasticity is debated in both stroke and healthy individuals (humans and rodents). Moreover, HIIT may have a preventive role on stroke severity, as found in rodents. The potential role of HIIT in stroke rehabilitation is reinforced by findings showing its powerful neurogenic effect that might potentiate cognitive benefits induced by cognitive tasks. In addition, the clinical role of neuroplasticity observed in each hemisphere needs to be clarified by coupling more frequently to cellular/molecular measurements and behavioral testing.

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. Forelimb grip strength evaluated motor function while incremental exercise tests measured the endurance performance. Key neuroplasticity markers were assessed by Western blot. RESULTS: Both regimens were effective in enhancing both the speed associated with the lactate threshold and maximal speed at D8 and D15. Neuroplasticity markers were upregulated in the contralesional hemisphere after training contrary to the ipsilesional side. Grip strength completely recovered but is faster with HIIT4. CONCLUSIONS: HIIT with short and long intervals induced early aerobic fitness and grip strength improvements. Our findings revealed that neuroplasticity markers were upregulated in the contralesional cortex and hippocampus to promote functional recovery.

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 ± 0.28 m/s and 4.01 ± 0.27 m/s) with two shoe conditions where a stiff plate was added either in high (under the insole) or low location (between the midsole and outsole). Ground reaction forces, lower limb joint angles, net joint torques and work, as well as alignment between the resultant ground reaction force and the leg were analysed. Among the running speeds performed by the runners, the high location significantly decreased propulsive ground reaction forces, increased metatarsophalangeal joint dorsiflexion and ankle plantarflexion, induced an increased alignment between the resultant ground reaction force and the runner's leg, thus decreasing all the lower limb joint torques and the positive work at the knee joint compared to the low location. The results suggested that the high stiff plate location into the shoe should be considered for running performance perspectives, but care should be taken to not alter the perceived comfort and/or increase injury risks.

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. The extensor carpi radialis (ECR) and the extensor digitorum communis (EDC) were studied as representative of wrist and finger extensors. Ten participants performed isometric extension force-varying contractions in different postures on an ergometer recording resultant moment. The joint angle, the myotendinous junction displacement and activation were synchronously tracked using motion capture, ultrasound and electromyography. Muscle force was estimated via a musculoskeletal model using the measured joint angle and moment. The force-length-activation relationship was then obtained by fitting a force-length model at different activation levels to the measured data. The obtained relationships agreed with previously reported data regarding muscle architecture, sarcomere length and activation-dependent shift of optimal length. Muscle forces estimated from kinematics and electromyography using the force-length-activation relationships were comparable, below 15% differences, to those estimated from moment via the musculoskeletal model. The obtained quantitative data provides a new insight into the different muscle mechanics of finger and wrist extensors. Graphical abstract By combining in vivo data (kinematics, dynamometry, electromyography, ultrasonography) during isometric force-varying contractions with musculoskeletal modelling, the force-length-activation relationships of both finger and wrist extensors were obtained. The results provided a new insight into the role of hand extensors in the generation and control of hand movements.

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±5.3 years) performed Stroop tasks and bimanual coordination tasks. Stroop tasks included neutral, congruent, and incongruent conditions. Response time and error rate were measured. Bimanual coordination tasks consisted of performing in-phase (IP) and anti-phase (AP) patterns. Participants were requested to switch as quickly as possible from one pattern to the other, resulting in two different switching directions (AP to IP; IP to AP). Mean and standard deviation (SD) of the continuous relative phase (CRP) were calculated pre- and post-switching for each participant. Total switching time (TST) was measured. The switching phase was also decomposed into reaction time (RT) and reversal time (REvT). Pearson correlation analyses were performed to test for correlations between: (i) SD of CRP and response time in Stroop tasks, and (ii) switching times (TST, RT, RevT) and response time in Stroop task, respectively. In addition, parallel mediation analyses were conducted. Results showed that: (i) the AP pattern was less stable than the IP pattern in both young and older adults, (ii) coordination patterns were less stable in older adults, (iii) response times in Stroop task were longer in the incongruent condition, and (iv) RespTs were longer in older than in young participants, whatever the condition. In the bimanual coordination task, RT, RevT, and TST increased with age. The stability of the IP pattern was correlated with the response times observed in neutral and congruent conditions, while the stability of the AP pattern was correlated with response time observed in the incongruent condition. Correlation and mediation analyses showed that, in the AP to IP switching direction, RT and RevT were both significantly correlated with response times observed in the incongruent condition of Stroop task. These findings suggest that inhibition processes are involved in switching between bimanual coordination patterns, at least to trigger the early phase of switching. They also support the hypothesis that inhibition processes are more involved in maintaining the AP pattern and switching to the IP pattern. Finally, age-related changes in switching times seem to be prominently mediated by alterations of inhibition processes.

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. It combines experimental measurements and a musculoskeletal model including the force-length relationship of the four prime muscles used in grasping. Participants exerted their maximum grip force on a cylindrical dynamometer in four different wrist postures, including one freely chosen by participants (spontaneous). A musculoskeletal model computed the muscle force level and length from motion capture and muscle activation. Results revealed that participants exerted maximum grip force spontaneously, with a loss of force when using other postures. At muscle force and length level, grip force variation seems to be associated with all the muscles under study. This observation led to a first quantitative link between power grip, posture and muscle properties, which could provide more insight into neuromechanical interaction involved when grasping. The design of ergonomic devices could also benefit from this quantification of the relationship between wrist angle and muscle length properties.

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 (10.8 ± 1.1 km h-1 on average) using four shoe prototypes with features combining low or high magnitudes of energy return and longitudinal bending stiffness. RESULTS: Neither the energy return, nor the longitudinal bending stiffness, or the interaction of these shoe features altered the energetic cost of running. High energy return shoes induced significant increased ground contact time from 274.5 ± 18.3 to 277.1 ± 18.7 ms, and significant decreased stride frequency from 1.34 ± 0.05 to 1.33 ± 0.05 Hz. High bending stiffness shoes induced significant increased ground contact time from 273.8 ± 18.2 to 277.9 ± 18.7 ms, significant increased vertical stiffness from 23.2 ± 3.4 to 23.8 ± 3.0 kN m-1, and significant decreased net vertical impulse from 245.4 ± 17.2 to 241.7 ± 17.5 BW ms. CONCLUSIONS: Increased energy return and longitudinal bending stiffness induced subtle changes in the running biomechanics, but did not induce any decrease in the energetic cost of running.

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. A vertical force platform sensor measured the force exerted by climbers when performing pull-ups under six different grip conditions (gym-bar, large climbing hold, and four small climbing holds: 22mm, 18mm, 14mm, and 10mm). The electromyography of finger flexors and extensor muscles were recorded simultaneously. The maximal arm power and summed mechanical work were computed. The results revealed that the number of pull-ups, maximal power, and summed mechanical work decreased significantly with the size of the climbing hold used, even if no differences were found between a large climbing hold and a gym-bar. Electromyography of the forearm muscles revealed that the use of a climbing hold generated finger flexor fatigue and that the level of cocontraction was impacted by the different segment coordination strategies generated during the pull-ups. These findings are likely to be useful for quantifying training loads more accurately and designing training exercises and programs.

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. METHODS: Eleven participants performed two sessions: (i) one for the wrist flexor muscles and (ii) one for the finger flexor muscles. For each session, the participants performed two maximal voluntary contractions and then two progressive isometric ramps from 0% to 100% of their maximal force capacity at five different wrist/metacarpophalangeal angles. Torque, kinematic, and electromyographic data were recorded. An ultrasound scanner was used to measure the myotendinous junction displacement of flexor carpi radialis (FCR) and flexor digitorum superficialis (FDS) during isometric contractions. A three-dimensional relationship between muscle length, force, and activation level was modeled using optimization procedure. RESULTS: Globally, the FCR was stronger and shorter compared with FDS. The results showed that the three-dimensional relationships fitted well the experimental data (mean R = 0.92 ± 0.07 and 0.87 ± 0.11 for FCR and FDS, respectively). Using joint angle and EMG data, this approach allows to estimate the muscle force with low estimation errors (<9% of Fmax). CONCLUSIONS: This study proposes a new method to investigate the force-length relationship by combining ultrasound measurement, musculoskeletal modeling and optimization procedures. The data and relationships provide a new insight into hand biomechanics and muscle function that could be useful for designing hand tools or surgical operations.

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. METHODS: Thirteen participants performed maximal isometric flexions of the fingers in two configurations: power grip (Power) and finger-pressing on a surface (Press). Hand kinematics and force/moment measurements were used as inputs in a musculoskeletal model of the hand to determine muscular tensions and co-contraction. EMG-EMG coherence analysis was performed between wrist and finger flexors and extensor muscle pairs in alpha, beta and gamma frequency bands. RESULTS: Concomitantly with tailored muscle force coordination and increased co-contraction between Press and Power (mean difference: 48.08%; p < 0.05), our results showed muscle-pair-specific modulation of intermuscular coupling, characterized by pair-specific modulation of EMG-EMG coherence between Power and Press (p < 0.05), and a negative linear association between co-contraction and intermuscular coupling for the ECR/FCR agonist-antagonist muscle pair (r = - 0.65; p < 0.05). CONCLUSIONS: This study brings new evidence that pair-specific modulation of EMG-EMG coherence is related to modulation of muscle force coordination during hand contractions. Our results highlight the functional importance of intermuscular coupling as a mechanism contributing to the control of muscle force synergies 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 assessment of the residual interactions between cortical and muscles activity with corticomuscular coherence (CMC) in participants with SCI producing different force levels may shed new lights on the regulation of muscle co-activation. To achieve this aim, we compared the net joint torque, the muscle co-activation and the CMC ~ 10 and ~ 20 Hz with both agonist and antagonist muscles in participants with SCI and healthy participants performing actual isometric elbow flexion contractions at three force levels. For all participants, overall CMC and muscle co-activation decreased with the increase in the net joint torque, but only CMC ~ 10 Hz was correlated with muscle co-activation. Participants with SCI had greater muscle co-activation and lower CMC ~ 10 Hz, at the highest force levels. These results emphasize the importance of CMC as a mechanism that could take part in the modulation of muscle co-activation to maintain a specific force level. Lower CMC ~ 10 Hz in SCI participants may reflect the decreased cortical influence on spinal mechanisms, leading to increased muscle co-activation, although plasticity of the corticomuscular coupling seems to be preserved after SCI to modulate the force level. Clinically, the CMC may efficiently evaluate the residual integrity of the neuromuscular system after SCI and the effects of rehabilitation.

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. Using these data, the muscle capacities of the main muscle groups of the hand (wrist flexors, wrist extensors, finger flexors, finger extensors, and intrinsic muscles) were estimated using a musculoskeletal model. These capacities were then used to compute the extensor/flexor capacity ratios about the wrist and the finger joints. Compared to healthy non-players, healthy players presented higher extensor muscle capacities and greater capacity ratios showing that playing tennis generates specific adaptations of muscle capacities. Interestingly, symptomatic players, similar to those of non-players, showed more imbalanced ratios than healthy players. These results confirm that the ratio of extensor/flexor muscle capacities seems to be associated with lateral epicondylalgia and can be further used to understand its incidence and consequences.

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. Using 14 expert players, a wide range of excitations at spectral and temporal levels were investigated. Energetic and spectral descriptors of stroke-induced vibration occurring at the racket handle and at the player's wrist and elbow were computed. Results indicated that vibrational characteristics are strongly governed by grip force and to a lower extent by the racket properties. Grip force management drives the amount of energy, as well as its distribution, into the forearm. Furthermore, hand-grip can be assimilated to an adaptive filter which can significantly modify the spectral parameters propagating into the player's upper limb. A significant outcome is that these spectral characteristics are as much dependent on the player as on the racket. This contribution opens up new perspectives in equipment manufacture by underlining the need to account for player/racket interaction in the design process.