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Concentric and eccentric contractions show different patterns of neural activity at both peripheral and cortical levels, which are thought to influence the perception of action properties such as the weight of objects moved by others. The aim of this study was to investigate how the type of muscle contraction influences weight estimation during action observation.Forty‐eight volunteers completed the Main experiment and the Control experiment. In the Main experiment, they performed a weight discrimination video task in which they watched videos of an actor moving two objects, a comparison, and a reference box, executing concentric or eccentric contractions and they had to indicate which box was the heaviest. Sensitivity analysis and psychometric functions were used to analyse the data. In the Control experiment, observers judged the actor's effort in moving the boxes.The results of the Main experiment showed that the weight discrimination sensitivity was higher in the eccentric condition for the light boxes. Conversely, for the heaviest boxes, discrimination sensitivity was higher in the concentric condition. These results were confirmed by the psychometric function analysis. The control experiment showed that the perceived difference in effort between the comparison and reference stimuli was greater in the eccentric than in the concentric condition for light stimuli.These results showed that the ability to evaluate the weight of the object involved in the observed action was influenced by the type of contraction and the amount of weight. The effort attributed to the actor influenced the observer's perception. [ABSTRACT FROM AUTHOR]

Local vibration (LV) mainly stimulates primary afferents (Ia) and can induce a tonic vibration reflex (TVR) and an illusion of movement. This study aimed to evaluate the effect of these two phenomena on maximal voluntary isometric contraction (MVIC) capacity. LV (80 Hz) was applied to the wrist flexor muscles in two randomized experiments for 6 min. LV conditions were adjusted to promote either TVR (visual focus on the vibrated wrist) or ILLUSION [hand hidden, visual focus on electromyographic activity of the flexor carpi radialis muscle (FCR)]. Mechanical and electromyographic (EMG) responses of the FCR and extensor carpi radialis muscles were recorded during MVIC in flexion and extension and during electrically evoked contractions at supramaximal intensity. Measurements were performed before (10 min and just before) and after (0 and 30 min) LV protocol. An increase in FCR EMG was observed during LV in the TVR condition (+340%) compared with the illusion condition (P = 0.003). In contrast, the movement illusion was greater in the ILLUSION condition (assessed through subjective scales) (P = 0.004). MVIC was reduced in flexion only after the TVR condition (≈ − 7 % , all P < 0.034). Moreover, the decrease in force was correlated with the amount of TVR recorded on the FCR muscle (r = −0.64, P = 0.005). Although potentiated doublets of each muscle did not evolve differently between conditions, a decrease was observed between the first and the last measure. In conclusion, when conducting research to assess maximal strength, it is necessary to have better control and reporting of the phenomena induced during LV. NEW & NOTEWORTHY: The maximal force production of the vibrated muscle is reduced after 6 min of LV only in TVR condition. Furthermore, the amount of TVR is negatively correlated with this force decrease. When measuring the effects of LV on maximal force production, it is important to control and report any phenomena induced during vibration, such as TVR or movement illusion, which can be achieved by recording EMG activity of vibrated muscle and quantifying illusion. [ABSTRACT FROM AUTHOR]

A typical weekly periodization strategy in soccer positions the most demanding sessions four and three days before the match-day (MD-4/MD-3). However, a modified periodization strategy could intersperse the two most demanding sessions with a low-load training session. This study aimed to investigate the impact of these periodizations on external loads and MD readiness. Twenty academy players were tested. The modified weekly periodization strategy included a low-load training session between the two most demanding sessions, while the typical periodization implemented them consecutively. Players wore a GPS and rated their perceived exertion (RPE) during the most demanding sessions. Players were also tested using a CMJ, a 20-m sprint, the Illinois agility test (IAT), and the Hooper questionnaire on MD-4 to obtain baseline values (CONTROL) and on the match-day (TEST). CONTROL values were similar during experimental weeks. During the second most demanding session, players covered greater distances for the modified versus the typical periodization in the 20-25 km/h (306.3 ± 117.1 m vs. 223.5 ± 92.2 m, p < 0.05) and >25 km/h speed zones (89.5 ± 44.8 m vs. 67.2 ± 44.5 m, p < 0.05). On the MD, CMJ, 20-m sprint, and IAT performances were similar between both periodizations. However, 10-m time (1.89 ± 0.10 s vs. 1.92 ± 0.09 s, p < 0.05) and the Hooper index score (7.90 ± 2.14 a.u. vs. 9.50 ± 3.44 a.u., p < 0.05) were significantly lower during the modified periodization strategy. A decreased training load session positioned between the most demanding sessions may be of interest in elite academy soccer players as it can lead to increased weekly external loads and readiness on the MD. [ABSTRACT FROM AUTHOR]

The aim of the present study was to investigate the effect of weighted vest on-field small-sided games (SSG) soccer training, during the in-season period, on body composition and soccer-specific performances, in young, trained soccer players. A counterbalance study design was adopted, in which the fourteen well-trained players (age: 19.1 ± 0.5 yrs, body mass: 70.3 ± 5.3 kg, body height: 180.3 ± 3.0 cm, body fat: 9.2 ± 4.1%) performed both the Interventional (Vest) and Control (Con) training routines (6 weeks/season; 5 training sessions/week; 1 match/week), in different occasions (winter/spring period). Con group followed a regular weekly training plan. When the Con group performed their intense training sessions, Vest group performed only the on-field SSGs training wearing a vest (12.5% of athletes' body mass). All the evaluations were performed one week before and after each training period. Statistical analyses include repeated ANOVA and T-test (p < 0.05). Significant increases in sprinting, jumping, change of direction (COD), aerobic and anaerobic performances were observed only after Vest intervention (−4.7 ± 2.2% to 11.2 ± 4.2%; p < 0.05). Significant changes were observed only after Vest training, compared to Cont (p < 0.05). These results suggest that using a weighted vest, during the in-season, onfield SSG training two times/week induces greater increases in young soccer players' sprinting, jumping, COD, aerobic and anaerobic performances. [ABSTRACT FROM AUTHOR]

Local vibration (LV) applied over the muscle tendon constitutes a powerful stimulus to activate the muscle spindle primary (Ia) afferents that project to the spinal level and are conveyed to the cortical level. This study aimed to identify the neuromuscular changes induced by a 30-min LV-inducing illusions of hand extension on the vibrated flexor carpi radialis (FCR) and the antagonist extensor carpi radialis (ECR) muscles. We studied the change of the maximal voluntary isometric contraction (MVIC, experiment 1) for carpal flexion and extension, motor-evoked potentials (MEPs, experiment 2), cervicomedullary motor-evoked potentials (CMEPs, experiment 2), and Hoffmann's reflex (H-reflex, experiment 3) for both muscles at rest. Measurements were performed before (PRE) and at 0, 30, and 60 min after LV protocol. A lasting decrease in strength was only observed for the vibrated muscle. The reduction in CMEPs observed for both muscles seems to support a decrease in alpha motoneurons excitability. In contrast, a slight decrease in MEPs responses was observed only for the vibrated muscle. The MEP/CMEP ratio increase suggested greater cortical excitability after LV for both muscles. In addition, the H-reflex largely decreased for the vibrated and the antagonist muscles. The decrease in the H/CMEP ratio for the vibrated muscle supported both pre- and postsynaptic causes of the decrease in the H-reflex. Finally, LV-inducing illusions of movement reduced alpha motoneurons excitability for both muscles with a concomitant increase in cortical excitability. [ABSTRACT FROM AUTHOR]

The purpose of the present study was to investigate effect of post-activation performance enhancement (PAPE) induced by the eccentric half-squat exercise on vertical jump performance in male jumpers. The jumping height, peak power, and work were measured and evaluated in twenty male jumpers (age: 21.2 ± 1.7 years, height: 191.1 ± 3.3 cm, body mass: 81.56 ± 7.3 kg) who participated in the national championship last year. Participants performed five eccentric half-squats at 85% of their one-repetition maximum (1 RM), with a knee angle below 90°, followed by immediate and 2 min delayed jump assessments using the Squat Jump (SJ) and Countermovement Jump (CMJ) tests. Results showed that this specific PAPE protocol did not significantly improve jump performance for the SJ (Height: ES = 0.613, p = 0.462, Work: ES = 0.124, p = 0.231, Power: ES = 0.382, p = 0.125) or CMJ (Height: ES = 0.523, p = 0.368, Work ecc: ES = 0.133, p = 0.505 (only main effect time p < 0.05), Work con: ES = 0.114, p = 0.101, Power ecc: ES = 0.134, p = 0.177, Power con: ES = 0.182, p = 0.195, Leg stiffness: ES = 0.095, p = 0.358) tests. Factors such as stimulus specificity, rest intervals, muscle length, and the balance between potentiation and fatigue may explain these results. This study highlights the complexity of PAPE responses and suggests that a single set of eccentric squats with a short rest may not improve jump performance in male jumpers. Further research is required to optimize the interplay between conditioning stimuli and rest periods to maximize PAPE effects in athletic performance enhancement. [ABSTRACT FROM AUTHOR]

Our study aimed to combine psychological and physical factors to explore the impact of the menstrual cycle on performance in elite academy women soccer players through weekly monitoring. Eighteen elite academy women soccer players were monitored. Players reported daily through an online anonymous survey if they were in menstruation. Players answered the Hooper Questionnaire daily, performed an Illinois Agility Test (IAT) twice a week, and rated their perceived exertion (RPE) after every training session. Tests were associated with a complete menstrual cycle reported through the online anonymous survey to determine the two weeks of the follicular phase and the two weeks of the luteal phase. Of the 18 players, 10 completed all requirements and were retained for analyses. IAT did not show significant differences throughout the menstrual cycle (p = 0.633). Fatigue (p = 0.444), Stress (p = 0.868), Sleep (p = 0.398), DOMS (delayed onset muscle soreness; p = 0.725), and Hooper Index (p = 0.403) did not show significant differences either. RPE was also comparable across the cycle (p = 0.846). Our results failed to demonstrate that hormonal variation during the menstrual cycle influenced psychological and physical markers of performance. [ABSTRACT FROM AUTHOR]

Featured Application: The application of short durations (≤6 min) for local vibration (LV) to the knee extensor muscles does not induce a significant loss of maximal isometric force production. The prolonged application (>20 min) of local vibration (LV) on muscles or tendons is known to reduce maximal isometric strength. However, the effect of short vibration durations (≤6 min) is still unknown. In fourteen participants, the changes in maximal voluntary isometric contraction (MVIC) were measured after 1, 3, and 6 min of rest (CONT) or local vibration (LV) over the quadricipital tendon (frequency: 100 Hz; amplitude: 0.5 mm). Before and after each condition, the amplitude of the twitch induced by a 100 Hz potentiated electrical doublet (PDPOT); the relative electromyographic activity of the vastus medialis and rectus femoris muscle during the MVIC (RMSMVIC.M−1); the torque developed 50 ms after the onset of contraction (T50); and the voluntary activation level (VAL) were evaluated. None of the three LV durations significantly changed the MVIC compared with the control condition (p = 0.379). The indices of central (i.e., VAL, T50, RMSMVIC.M−1) and peripheral (e.g., PDPOT) fatigue were unaffected (p > 0.147). In conclusion, a short-duration LV (≤6 min) on a voluminous muscle group does not impair maximal force production or induce any central or peripherical fatigue. [ABSTRACT FROM AUTHOR]

Body weight support (BWS) and incline running (IR) are commonly used either during rehabilitation or during training separately, with many positive effects on athletes' performance and rehabilitation. The aim of the present study was to investigate the interaction between bodyweight support and incline running on the electromyographic activity of the triceps surae and compare it to flat running. In eighteen healthy men (age: 20.3 ± 1.2 years, body weight: 70.2 ± 4.8 kg, body height: 179.6 ± 5.4 cm), the changes in electromyographic activity (EMGA) during a 10 min run with BWS (15% or 30% of body weight; in different occasions) and IR at 7%, as well as jumping performance and gait spatiotemporal parameters, were evaluated. A lower Rating of Perceived Exertion and a significant decrease in the size of the Vastus Lateralis (VL) (33.4%), Soleus (SOL) (17%), and Gastrocnemius Lateralis (GL) EMGA (28.5%, p < 0.05) but not in Gastrocnemius Medialis (GM) (10.5%, p > 0.05), was observed during BWS30% at 7% slope compared to flat running. Also, low-frequency fatigue of the quadriceps was induced only after running without BWS on a 7% slope (p = 0.011). No changes were found in jumping performance (p = 0.246) and gait spatiotemporal parameters (p > 0.05) except for flight time (p < 0.006). In conclusion, running with a slope of 7% and 30% of BWS can result in EMG activity comparable to that observed during level running. This method can also be used in prevention and rehabilitation training programs without creating fatigue. [ABSTRACT FROM AUTHOR]

In elite-level youth soccer players, weekly training periodization is of paramount importance to plan for short- and long-term physical development. The present study investigated current practices for physical periodization strategies in elite male French academies. An online survey was completed by elite French academies strength and conditioning coaches to determine the typical weekly periodization with particular reference to daily training in relation to match day (MD) in youth soccer players. The survey attempted to characterize the importance of physical development compared to match result, and practices used (expected difficulty and content) for each training session according to duration, exercises, and objective. The frequency rates of the responses were compared using two-tailed Chi-square tests with the significance level set at p < 0.05. Forty-five questionnaires were analyzed. Respondents indicated that their training sessions focused mainly on physical development (95.6%) rather than match result. Active recovery (34.2%) and aerobic conditioning exercises (40.8%) were primarily conducted on MD+1 and MD+2 using passing circuits and aerobic technical drills. Physical development was mostly pursued during sessions on MD-4 (38.8%) and MD-3 (37.3%). The number of large-sided games was highest on MD-3 (58.1%). On MD-2 and MD-1, a decrease in the training load was highlighted, with speed (40.4%) and tapering sessions (52.4%) mostly implemented. Intensive use of small-sided games (92.3%) and reactivity exercises was observed at MD-1 (100.0%). Our results revealed discrepancies between the physical objectives set for each day and the content implemented, which could potentially be more physically demanding than expected. [ABSTRACT FROM AUTHOR]

Action observation and action execution are tightly coupled on a neurophysiological and a behavioral level, such that visually perceiving an action can contaminate simultaneous and subsequent action execution. More specifically, observing a model in postural disequilibrium was shown to induce an increase in observers' body sway. Here we reciprocally questioned the role of observers' motor system in the contagion process by comparing participants' body sway when watching displays of antero-posterior vs. lateral imbalance. Indeed, during upright standing, biomechanical constraints differ along the antero-posterior (A-P) and medio-lateral (M-L) axes; hence an impact of observers' postural constraints on the contagion response would result in different reactions to both types of stimuli. In response to the displays, we recorded greater area of center of pressure (CoP) displacement when watching forward/backward compared to left/right imbalance. In addition, after normalizing A-P and M-L CoP displacements by a control condition (fixation cross), A-P CoP path length when viewing forward imbalance tended to be higher than M-L CoP path length when viewing imbalance to the left or right. These results indicate that postural contagion is promoted when the display is compatible with observers' motor stabilization strategy which is mainly oriented along the A-P axis. In terms of clinical application, this study brings new indications for adaptation of observational training devices in rehabilitation programs. (Contains 2 figures.)

In 2019-2020 and 2020-2021, the COVID-19 pandemic led to unexpected behavioral restrictions, allowing only the individual training of the athletes. The purpose of the present study was to record the effects of a home-based training program on physical performance at a semi-professional level, after the Covid-19 confinement, in terms of external load. Twenty soccer players from one semi-professional team participated in this study. The data was collected by GPS devices, with an accelerometer and gyroscope, and a sampling rate 10Hz. The external load is evaluated by the total distance, the high-intensity runs, the sprint distance as well as the number of accelerations and decelerations. Three matches before and twelve games after the lockdown were analyzed and compared. During the confinement period, the players performed 5-6 training sessions per week. This period lasted over 4 four months. The training sessions were monitored by a free smartphone application. Similarly, the players communicated with the technical staff with a free internet application. The results showed significant increases (p < 0.05) in the total distance covered during the matches after the intervention. No significant increase in highintensity runs and the number of accelerations were found (p > 0.05). The present data suggest that an intervention monitored by a free application could improve athletic performance at the semi-professional level, even after long-term abstinence from team training such as quarantine or off-season periods. These data might provide affordable solutions to the semi-professional soccer teams, which could be used during the off-season period leading to reduce detraining effects and higher performance in the forthcoming championship. [ABSTRACT FROM AUTHOR]

The present study investigated the influence of a 5-week electrostimulation (EMS) training program on muscular strength, kicking velocity, sprint, and vertical jump performance in soccer players. Twenty amateur soccer players participated in the study, 10 in the electrostimulated group and the remaining 10 in a control group. Electrostimulation was applied on the quadriceps muscles over 5 weeks. Subjects were tested before, during (wk-3), and after (wk-5) the EMS training program. Maximal voluntary contraction using different contraction mode (i.e., eccentric, concentric, and isometric), vertical jump height, sprint running for 10 m, and ball speed were examined. We observed an increase in isometric and eccentric maximal knee extension torques and also a gain in ball speed performance without run up at wk-3. After 5 weeks of EMS training, eccentric, isometric, and concentric torques and ball speed had significantly improved. It appeared appropriate to conduct EMS training during at least 3 weeks to observe beneficial effects in specific soccer skills such as ball speed. Key Words ball speed, knee extensors, isokinetic dynamometer, isometric and eccentric strength

Oxygen uptake (V̇O2), heart rate (HR), energy cost (EC) and oxygen pulse are lower during downhill compared to level or uphill locomotion. However, a change in oxygen pulse and EC during prolonged grade exercise is not well documented. This study investigated changes in cardiorespiratory responses and EC during 45-min grade exercises. Nine male healthy volunteers randomly ran at 75% HR reserve during 45-min exercise in a level (+1%), uphill (+15%) or downhill (−15%) condition. V̇O2 , minute ventilation (V̇E) and end-tidal carbon dioxide (Pet CO2) were recorded continuously with 5-min averaging between the 10th and 15th min (T1) and 40th and 45th min (T2). For a similar HR (157±3 bpm), V̇O2 , V̇E , and Pet CO2 were lower during downhill compared to level and uphill conditions (p<0.01). V̇O2 and V̇E decreased similarly from T1 to T2 for all conditions (all p<0.01), while Pet CO2 decreased only for the downhill condition (p<0.001). Uphill exercise required greater EC compared to level and downhill exercises. EC decreased only during the uphill condition between T1 and T2 (p<0.01). The lowest V̇O2 and EC during downhill exercise compared to uphill and level exercises suggests the involvement of passive elastic structures in force production during downhill. The lower cardiorespiratory response and the reduction in Pet CO2 during downhill running exercise, while EC remained constant, suggests an overdrive ventilation pattern likely due to a greater stimulation of efferent neural factors. [ABSTRACT FROM AUTHOR]

Purpose: To examine the acute effect of a single static-stretching session of hamstring muscles on torque production in relation with individual flexibility. Methods: Maximal voluntary concentric torque of hamstring muscles was measured before and after a static-stretching session (6 × 30 s). Torque changes were correlated with the flexibility level determined at the onset of the experimental procedure. Results: The hamstring-stretching intervention significantly reduced maximal concentric torque in participants with low and high hamstring flexibility. Hamstring flexibility and torque decrease, determined immediately after the stretching procedure, were negatively correlated. Conclusions: Torque decrease measured after the static-stretching session is dependent on participant flexibility. Participants with low flexibility are much more likely to demonstrate large torque decreases poststretching. [ABSTRACT FROM AUTHOR]

The present study assessed neuromuscular and corticospinal changes during and after a fatiguing submaximal exercise of the knee extensors in different modes of muscle contraction. Twelve subjects performed two knee extensors exercises in a concentric or eccentric mode, at the same torque and with a similar total impulse. Exercises consisted of 10 sets of 10 repetitions at an intensity of 80% of the maximal voluntary isometric contraction torque (MVIC). MVIC, maximal voluntary activation level (VAL) and responses of electrically evoked contractions of the knee extensors were assessed before and after exercise. Motor evoked potential amplitude (MEP) and cortical silent period (CSP) of the vastus medialis (VM) and rectus femoris (RF) muscles were assessed before, during and after exercise. Similar reductions of the MVIC (−13%), VAL (−12%) and a decrease in the peak twitch (−12%) were observed after both exercises. For both VM and RF muscles, MEP amplitude remained unchanged during either concentric or eccentric exercises. No change of the MEP amplitude input-output curves was observed post-exercise. For the RF muscle, CSP increased during the concentric exercise and remained lengthened after this exercise. For the VM muscle, CSP was reduced after the eccentric exercise only. For a similar amount of total impulse, concentric and eccentric knee extensor contractions led to similar exercise-induced neuromuscular response changes. For the two muscles investigated, no modulation of corticospinal excitability was observed during or after either concentric or eccentric exercises. However, intracortical inhibition showed significant modulations during and after exercise.  [ABSTRACT FROM AUTHOR]

Although plentiful data are available regarding mental states involving the dominant-right arm, the evidence for the nondominant-left arm is sparse. Here, we investigated whether right-handers can generate accurate predictions with either the right or the left arm. Fifteen adults carried out actual and mental arm movements in two directions with varying inertial resistance (inertial anisotropy phenomenon). We recorded actual and mental movement times and used the degree of their similarity as an indicator for the accuracy of motor imagery/prediction process. We found timing correspondences (isochrony) between actual and mental right arm movements in both rightward (low inertia resistance) and leftward (high inertia resistance) directions. Timing similarities between actual and mental left arm movements existed for the leftward direction (low inertia resistance) but not for the rightward direction (high inertia resistance). We found similar results when participants reaching towards the midline of the workspace, a result that excludes a hemispace effect. Electromyographic analysis during mental movements showed that arm muscles remained inactivate, thus eliminating a muscle activation strategy that could explain intermanual differences. Furthermore, motor-evoked potentials enhancement in both right and left biceps brachii during mental actions indicated that subjects were actively engaged in mental movement simulation and that the disadvantage of the left arm cannot be attributed to the nonactivation of the right motor cortex. Our findings suggest that predictive mechanisms are more robust for the right than the left arm in right-handers. We discussed these findings from the perspective of the internal models theory and the dynamic-dominance hypothesis of laterality. [ABSTRACT FROM AUTHOR]

Mental imagery is a cognitive tool that helps humans take decisions by simulating past and future events. The hypothesis has been advanced that there is a functional equivalence between actual and mental movements. Yet, we do not know whether there are any limitations to its validity even in terms of some fundamental features of actual movements, such as the relationship between space and time. Although it is impossible to directly measure the spatiotemporal features of mental actions, an indirect investigation can be conducted by taking advantage of the constraints existing in planar drawing movements and described by the two-thirds power law (2/3PL). This kinematic law describes one of the most impressive regularities observed in biological movements: movement speed decreases when curvature increases. Here, we compared the duration of identical actual and mental arm movements by changing the constraints imposed by the 2/3PL. In the first two experiments, the length of the trajectory remained constant, while its curvature (Experiment 1) or its number of inflexions (Experiment 2) was manipulated. The results showed that curvature, but not the number of inflexions, proportionally and similarly affected actual and mental movement duration, as expected from the 2/3PL. Two other control experiments confirmed that the results of Experiment 1 were not attributable to eye movements (Experiment 3) or to the perceived length of the displayed trajectory (Experiment 4). Altogether, our findings suggest that mental movement simulation is tuned to the kinematic laws characterizing actions and that kinematics of actual and mental movements is completely specified by the representation of their geometry. [ABSTRACT FROM AUTHOR]

Background: Several studies bring evidence that action observation elicits contagious responses during social interactions. However automatic imitative tendencies are generally inhibited and it remains unclear in which conditions mere action observation triggers motor behaviours. In this study, we addressed the question of contagious postural responses when observing human imbalance. Methodology/Principal Findings: We recorded participants' body sway while they observed a fixation cross (control condition), an upright point-light display of a gymnast balancing on a rope, and the same point-light display presented upside down. Our results showed that, when the upright stimulus was displayed prior to the inverted one, centre of pressure area and antero-posterior path length were significantly greater in the upright condition compared to the control and upside down conditions. Conclusions/Significance: These results demonstrate a contagious postural reaction suggesting a partial inefficiency of inhibitory processes. Further, kinematic information was sufficient to trigger this reaction. The difference recorded between the upright and upside down conditions indicates that the contagion effect was dependent on the integration of gravity constraints by body kinematics. Interestingly, the postural response was sensitive to habituation, and seemed to disappear when the observer was previously shown an inverted display. The motor contagion recorded here is consistent with previous work showing vegetative output during observation of an effortful movement and could indicate that lower level control facilitates contagion effects. [ABSTRACT FROM AUTHOR]

The article presents the results of a study which investigated the results of combining gymnastics training with electromyostimulation (EMS) in middle-school-age girls. An overview of related previous research is provided, along with details of the experimental protocol. It was found that EMS produced benefits in terms of jump test performance.

Accelerations (ACC) and decelerations (DEC) are important and frequent actions in soccer. We aimed to investigate whether ACC and DEC were good indicators of the variation of training loads in elite women soccer players. Changes in the training load were monitored during two different selected weeks (considered a "low week" and a "heavy week") during the in-season. Twelve elite soccer women playing in the French first division wore a 10-Hz Global Positioning System unit recording total distance, distance within speed ranges, sprint number, ACC, DEC, and a heart rate monitor during six soccer training sessions and rated their perceived exertion (RPE). They answered the Hooper questionnaire (sleep, stress, fatigue, DOMS) to get an insight of their subjective fitness level at the start (Hooper S) and at the end of each week (Hooper E). A countermovement jump (CMJ) was also performed once a week. During the heavy week, the training load was significantly greater than the low week when considering number of ACC >2 m·s−2 (28.2 ± 11.9 vs. 56.1 ± 10.1, p < 0.001) and number of DEC < −2 m·s−2 (31.5 ± 13.4 vs. 60.9 ± 14.4, p < 0.001). The mean heart rate percentage (HR%) (p < 0.05), RPE (p < 0.001), and Hooper E (p < 0.001) were significantly greater during the heavy week. ACC and DEC showed significant correlations with most outcomes: HR%, total distance, distance per min, sprint number, Hooper index of Hooper E, DOMS E, Fatigue E, RPE, and session RPE. We concluded that, for elite women soccer players, quantifying ACC and DEC alongside other indicators seemed to be essential for a more complete training load monitoring. Indeed, it could lead to a better understanding of the reasons why athletes get fatigued and give insight into neuromuscular, rather than only energetic, fatigue. [ABSTRACT FROM AUTHOR]

The risk of falling increases with age. Individuals wearing unadapted shoes present an aggravating risk factor. The objective of this study was to determine the effectiveness of specifically designed balance shoes on balance and postural stability in healthy elderly people compared to that of their usual shoes. In total, 21 healthy individuals aged 65–84 years (76.0 ± 8.0 years) performed balance tests (bipedal with open or closed eyes, unipedal with open eyes, limits of stability, and step cadence) while wearing their (i) personal shoes or (ii) balance shoes (Axis Comfort Development©). Three test sessions were conducted with personal and balance shoes. The first served as the baseline, and the other two were performed after a familiarization period of several days with the personal or balance shoes. The perception of balance shoe efficiency was documented using a questionnaire. The balance shoes significantly improved bipedal balance with closed eyes. Moreover, the familiarization period significantly improved unipedal balance with open eyes. Most subjects felt safer and stabler using balance shoes. The investigated specifically designed balance shoes were effective in elderly individuals in improving postural balance compared to personal shoes. The balance shoes could, therefore, reduce the falling risk in healthy elderly people. [ABSTRACT FROM AUTHOR]

The purpose of the present study was to examine the effect of different conditioning activities (CAs) on short-term increase in sprint performance. In twelve male sprinters (21.1±2.6 years, 100 m performance: 11.5±0.6 s) their body composition, half squat maximum strength, 100 m sprinting and countermovement jump performances were evaluated. The performance of a 50 m sprint (splits at 10 m, 30 m and 50 m) was evaluated before and 5, 10 and 15 min after four postactivation performance enhancement CAs on different occasions: [1] 3 sets x 4 s maximum isometric half squat (IHF), [2] 3 sets x 3 consecutive countermovement jumps (cCMJs), [3] 3 repetitions x 30 m overspeed sprinting (OVSP) and [4] dynamic submaximal half squat (2 sets x 2 reps x 90% of 1-RM half squat; HSQ). Significant improvements of sprinting performance were found 10 and 15 min following the cCMJs, OVSP and HSQ's interventions, in all distances (p<.05; -2.14±1.21% and -3.56±2.47%), without any significant difference between these interventions and time points (p>.05). Significant inter-individual differences were found in the magnitude of sprint performance improvements as well as in the optimal time window (p<.05), with the stronger sprinters responding better after HSQs, while the more powerful sprinters after cCMJs and OVSPs. In conclusion, it seems that cCMJs, OVSP and HSQ can acutely increase sprinting performance after 10 min, but CA's induced increases in sprinting performance are highly related to the strength and power characteristics of each sprinter. [ABSTRACT FROM AUTHOR]

• Instructed-delay reaction time task involving concentric and eccentric contraction. • CSE tested from 300 ms before up to 40 ms after an imperative signal. • CSE significantly differs between contractions around the imperative signal. • Role of preparatory inhibition and attentional processing in eccentric contractions. Specific neural mechanisms operate at corticospinal levels during eccentric and concentric contractions. Here, we investigated the difference in corticospinal excitability (CSE) when preparing these two types of contraction. In this study we enrolled 16 healthy participants. They were asked to perform an instructed-delay reaction time (RT) task involving a concentric or an eccentric contraction of the right first dorsal interosseus muscle, as a response to a proprioceptive cue (Go signal) presented 1 s after a warning signal. We tested CSE at different time points ranging from 300 ms before up to 40 ms after a Go signal. CSE increased 300–150 ms before the Go signal for both contractions. Interestingly, significant changes in CSE in the time interval around the Go signal (from −150 ms to +40 ms) were only revealed in eccentric contraction. We observed a significant decrease in excitability immediately before the Go cue (Pre_50) and a significant increase 40 ms after it (Post_40) with respect to the MEPs recorded at Pre_150. Finally, CSE in eccentric contraction was lower before the Go cue (Pre_50) and greater after it (Post_40) compared to the concentric contraction. A similar result was also found in NoMov paradigm, used to disentangle the effects induced by movement preparation from those induced by the movement preparation linked to the proprioceptive cue. We could conclude that different neural mechanisms observed during concentric and eccentric contractions are mirrored with a different time-specific modulation of CSE in the preparatory phase to the movement. [ABSTRACT FROM AUTHOR]

Due to its high frequency of occurrence, as well as possible residual symptoms, proper treatment of lateral ankle sprains (LAS) is important. From a physiological point of view, increasing the quantity of electromyographic (EMG) activity in the peroneal muscles will mechanically improve the functional stability of the ankle joint. The present study investigated the immediate effects of an ankle destabilization device (ADD) specifically designed to induce imbalances along the Henke's axis during 3 challenging walking tasks. As the effects of such a device have to be tested on healthy participants before being implemented in rehabilitation programs, 12 healthy participants performed 3 different types of walking (normal, aligned, and jumping walking) while the EMG activities in four peroneal muscles and the main gait kinematics parameters were recorded. Our results clearly demonstrated that wearing the ADD during these different walking tasks significantly increased EMG activities in the four peroneal muscles (increases from 9 to 33% on average depending on the muscle and the walking condition) while maintaining previous gait kinematic patterns. Our study shows that an ADD coupled with walking or jumping tasks is able to improve neuromuscular activity. It should therefore be useful for ankle rehabilitation therapy and the prevention of LAS. [ABSTRACT FROM AUTHOR]

Abstract: Action observation influences action execution; this strong coupling is underlined by an overlap of cortical areas activated during observation and execution of action, and is dependent of specific motor experience. The goal of the present study was to verify if action observation can be used for rehabilitation of elderly people. We tested this question with a protocol of observational practice of 2 frequently used movements: walking and sit-to-stand/back-to-sit. Both tasks were performed at normal and maximal speed before and after training, by 8 elderly subjects. Observational practice led to an increase in walking velocity via an increase in step frequency, but without modification of step length. In addition, we noted a reduction in BTS duration, but no modification of STS duration. These results highlight the fact that observational practice induces a reactivation in mental representation of action, and may lead to better movement control. Overall, observational practice offers interesting perspectives for rehabilitation of elderly people. [Copyright &y& Elsevier]

Weekly training loads are typically reported using absolute values and are not individualized according to competition positional demands (relative values). The aim of this study was to evaluate absolute and relative training loads and compare across playing positions during a full in-season in an elite soccer academy. 24 elite academy soccer players, categorized into five positions (CD: central defender [n = 4]; FB: full back [n = 5]; CM: central midfielder [n = 6]; WM: wide midfielder [n = 5]; FW: forward [n = 4]), were monitored using a global positioning system. Absolute training load was calculated using the total distance, the distance at moderate-speed ([15-20[ km·h -1 ), high-speed ([20-25[ km·h -1 ), sprint (> 25 km·h -1 ), the total number of accelerations (> 3 m·s -2 ) and decelerations (< -3 m·s -2 ). Relative training load was calculated by dividing absolute training loads by mean values from the competitive matches. Training loads were determined daily according to their distance from match day (MD). One-way ANOVAs were performed to evaluate differences between playing positions. Absolute moderate-speed distance was greater for WM compared to CD (p = 0.015, and p = 0.017), while the opposite was shown for relative values (p = 0.014, and p < 0.001) on MD-4 and MD-3, respectively. The absolute moderate-speed distance was not different between CD, FB, CM, and FW, whereas relative values were greater for CD on MD+2 and MD-4 (p < 0.05). FB and WM performed greater absolute high-speed distance than CD on MD-4 and MD-3 (p < 0.05) while no difference was highlighted for relative values.Our results demonstrated that in the present academy players, training load for CD was underestimated using absolute training loads for moderate and high-speed distances. In contrast, relative training loads highlighted WM as an underloaded position. Therefore, relative training loads are recommended as they contextualize training loads according to competitive demands and favor training individualization., (© Journal of Sports Science and Medicine.)

The study analyzed neural mechanisms mediating spinal excitability modulation during eccentric (ECC) movement (passive muscle lengthening, submaximal, and maximal ECC contractions) as compared with concentric (CON) conditions. Twenty-two healthy subjects participated in three experiments. Experiment A ( n = 13) examined D 1 presynaptic inhibition (D 1 PI) and recurrent inhibition (RI) modulation during passive muscle lengthening and shortening, by conditioning the soleus (SOL) H-reflex with common peroneal nerve submaximal and tibial nerve maximal stimulation, respectively. Experiment B ( n = 13) analyzed the effect of passive muscle lengthening on D 1 PI and heteronymous Ia facilitation (HF, conditioning the SOL H-reflex by femoral stimulation). Experiment C ( n = 13) focused on the effect of muscle contraction level (20%, 50%, and 100% of maximal voluntary contraction) on D 1 PI and RI. Results showed a significantly higher level of D 1 PI during passive muscle lengthening than shortening ( P < 0.01), whereas RI and HF were not affected by passive muscle movement. D 1 PI and RI were both higher during ECC as compared with CON contractions ( P < 0.001). However, the amount of D 1 PI was independent of the torque level, whereas RI was reduced as the torque level increased ( P < 0.05). The decreased spinal excitability induced by muscle lengthening during both passive and active conditions is mainly attributed to D 1 PI, whereas RI also plays a role in the control of the specific motoneuron output during ECC contractions. Both inhibitory mechanisms are centrally controlled, but the fact that they evolve differently with torque increases, suggests a distinct supraspinal control. NEW & NOTEWORTHY Presynaptic (PI) and recurrent inhibitions (RI) were studied during passive muscle lengthening and eccentric contractions. Results indicate that the increased PI during passive muscle lengthening accounts for the decreased spinal excitability at rest. During eccentric contraction both mechanisms contribute to spinal excitability modulation. The same amount of PI was observed during eccentric contractions, while RI decreased as developed torque increased. This distinct modulation according to torque level suggests a distinct supraspinal control of these mechanisms.

This study examined the influence of knee extensors' hip and knee angle on force production capacity and their neuromuscular and architectural consequences. Sixteen healthy men performed sub-maximal and maximal voluntary isometric contractions (MVIC) of knee extensors with four different combinations of the knee and hip angles. Muscle architecture, excitation-contraction coupling process, muscular activity, and corticospinal excitability were evaluated on the vastus lateralis (VL) and rectus femoris (RF) muscles. MVIC and evoked peak twitch (Pt) torques of knee extensors increased significantly ( p  < 0.05) by 42 ± 12% and 47 ± 16% on average, respectively, under knee flexed positions (110° flexion, 0° = full extension) compared to knee extended positions (20° flexion) but were not different between hip positions (i.e., 0° or 60° flexion). Knee flexion also affected VL and RF muscle and fascicle lengths toward greater length than under knee extended position, while pennation angle decreased for both muscles with knee flexion. Pennation angles of the VL muscle were also lower under extended hip positions. Alternatively, no change in maximal muscle activation or corticospinal activity occurred for the VL and RF muscles across the different positions. Altogether these findings evidenced that MVIC torque of knee extensors depended particularly upon peripheral contractile elements, such as VL and RF muscle and fascicle lengths, but was unaffected by central factors (i.e., muscle activation). Furthermore, the hip position can affect the pennation angle of the VL, while VL muscle length can affect the pennation angle of the RF muscle. These elements suggest that the VL and RF muscles exert a mutual influence on their architecture, probably related to the rectus-vastus aponeurosis., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Garnier, Lepers, Canepa, Martin and Paizis.)

Fixed-gear cycling performance during criteriums predominantly involves the aerobic system. Whether pacing is another important factor for performance is unknown. The purpose of the present study was to explore pacing and/or positioning strategies of fixed-gear riders during criteriums. Race results of an international fixed-gear criterium were analyzed (20 laps for women and 28 laps for men; laps = 1,270 m). Statistics were conducted on individuals lap time and positioning during the finals. Race pattern in women ( n = 35) and men ( n = 53) revealed that the faster laps ( P < 0.05) were in the middle and at the end of the race and the slower laps ( P < 0.05) were at the end of the race (laps 17-18 for women and lap 26 for men). The final ranking was significantly correlated with the mean race position (Kendall's tau = 0.664 and 0.689 for women and men, respectively). A coefficient of variation >50% revealed an important positioning variability. The best riders are mostly amongst the first during the race. However, the others exhibited larger mean position variations during the first half of the race. Our results demonstrated variable pacing strategies during fixed-gear criteriums. Although some riders had economical drafting strategies during the first half of the race, riding placed ahead during the whole race seemed to be an essential performance factor., (Copyright © 2020 Babault, Paizis, Trimble, Trimble and Cometti.)

Laterality is an important feature of motor behavior. Several studies have shown that lateralization in right-handed young adults (i.e., right versus left arm superiority) emerges also during imagined actions, that is when an action is internally simulated without any motor output. Such information, however, is lacking for elderly people and it could be valuable to further comprehend the evolution of mental states of action in normal aging. Here, we evaluated the influence of age on motor laterality during mental actions. Twenty-four young (mean age: 24.7 ± 4.4 years) and 24 elderly (mean age: 72.4 ± 3.6 years) participants mentally simulated and actually executed pointing movements with either their dominant-right or non-dominant-left arm in the horizontal plane. We recorded and analyzed the time of actual and mental movements and looked for differences between groups and arms. In addition, electromyographic activity from arm muscle was recorded to quantify any enhancement in muscle activation during mental actions. Our findings indicated that both groups mentally simulated arm movements without activating the muscles of the right or the left arm above the baseline level. This finding suggests that young and, notably, elderly adults are able to generate covert actions without any motor output. We found that manual asymmetries (i.e., faster movements with the right arm) were preserved in young adults for both actual and mental movements. In elderly adults, manual asymmetries were observed for actual but not for mental movements (i.e., equal movement times for both arms). These findings clearly indicate an age-related reduction of motor laterality during mental actions.