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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]

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. [ABSTRACT FROM AUTHOR]

Even though the acute effects of pre-exercise static stretching and dynamic muscle activity on muscular and functional performance have been largely investigated, their effects on the corticospinal pathway are still unclear. For that reason, this study examined the acute effects of 5×20 s of static stretching, dynamic muscle activity and a control condition on spinal excitability, corticospinal excitability and plantar flexor neuromuscular properties. Fifteen volunteers were randomly tested on separate days. Transcranial magnetic stimulation was applied to investigate corticospinal excitability by recording the amplitude of the motor-evoked potential (MEP) and the duration of the cortical silent period (cSP). Peripheral nerve stimulation was applied to investigate (i) spinal excitability using the Hoffmann reflex (Hmax), and (ii) neuromuscular properties using the amplitude of the maximal M-wave (Mmax) and corresponding peak twitch torque. These measurements were performed with a background 30% of maximal voluntary isometric contraction. Finally, the maximal voluntary isometric contraction torque and the corresponding electromyography (EMG) from soleus, gastrocnemius medialis and gastrocnemius lateralis were recorded. These parameters were measured immediately before and 10 s after each conditioning activity of plantar flexors. Corticospinal excitability (MEP/Mmax) was significantly enhanced after static stretching in soleus (P = 0.001; ES = 0.54) and gastrocnemius lateralis (P<0.001; ES = 0.64), and after dynamic muscle activity in gastrocnemius lateralis (P = 0.003; ES = 0.53) only. On the other hand, spinal excitability (Hmax/Mmax), cSP duration, muscle activation (EMG/Mmax) as well as maximal voluntary and evoked torque remained unaltered after all pre-exercise interventions. These findings indicate the presence of facilitation of the corticospinal pathway without change in muscle function after both static stretching (particularly) and dynamic muscle activity. [ABSTRACT FROM AUTHOR]

Locomotor exercise may induce corticospinal excitability and/or cortical inhibition change in the knee extensors. This study investigated whether the mode of muscle contraction involved during a locomotor exercise modulates corticospinal and intracortical responsiveness. Eleven subjects performed two 45-min treadmill walking exercises in an uphill (+ 15%) or a downhill (− 15%) condition matched for speed. Maximal voluntary isometric torque (MVIC), voluntary activation level (VAL), doublet (Dt) twitch torque, and M-wave area of the knee extensors were assessed before and after exercise. At the same time-points, motor-evoked potential (MEP), cortical silent period (CSP), and short-interval cortical inhibition (SICI) were recorded in the vastus lateralis (VL) and rectus femoris (RF) muscles. After exercise, uphill and downhill conditions induced a similar loss in MVIC torque (− 9%; p < 0.001), reduction in VAL (− 7%; p < 0.001), and in M-wave area in the VL muscle (− 8%; p < 0.001). Dt twitch torque decreased only after the downhill exercise (− 11%; p < 0.001). MEP area of the VL muscle increased after the downhill condition (p = 0.007), with no change after the uphill condition. MEP area of the RF muscle remained stable after exercises. CSP and SICI did not change in the two conditions for both muscles. Downhill walking induces an increase in MEP area of the VL muscle, with no change of the CSP duration or SICI ratio. The eccentric mode of muscle contraction during a locomotor exercise can modulate specifically corticospinal excitability in the knee extensors. [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]

Introduction: This study aimed to apply multifractal detrended fluctuation analysis (MFDFA) to surface EMG to detect neuromuscular changes after realistic warm-up procedures that was followed by various stretching exercises. Methods: Sixteen volunteers conducted two experimental sessions. Testing included two maximal voluntary contractions before, after a standardized warm-up, and after a stretching exercise (static or neurodynamic nerve gliding technique). EMG was registered on biceps femoris and semitendinosus muscles. EMG was analyzed using different parameters obtained from the singularity Hurst exponent function and multifractal power spectrum (both obtained from the multifractal detrended fluctuation analysis). Results: The Hurst exponent, α maximum, and peak value of the multifractal spectrum significantly decreased after warm-up as compared with baseline for both biceps femoris (P = 0.003, P = 0.006, and P = 0.003, respectively) and semitendinosus (P = 0.006, P = 0.013 and P = 0.01, respectively) muscles. No further alteration was obtained after static or neurodynamic nerve gliding stretching as compared with post-warm-up (P = 1.0). No significant difference was obtained for Hurst exponent range, width, and asymmetry of the multifractal spectrum (P > 0.05). Conclusions: From the present results, EMG depicted multifractal features sensitive to detect neuromuscular changes after a warm-up procedure. An increase in multiscale complexity is revealed after warm-up without any further alteration after stretching. The multifractal spectrum depicted dominant small fluctuations that shifted toward slightly larger fluctuations that could be attributed to motor unit recruitment. [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]

Highlights: [•] We analysed balance strategies and EMG activity using different unstable surfaces. [•] Centre of pressure displacements and EMG activity were affected by unstable boards. [•] Postural equilibrium is mostly oriented around the anteroposterior axis. [•] Results highlighted new knowledge about central nervous system organisation. [•] Balance is modulated by ecological strategies. [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]

Abstract: 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. [Copyright &y& Elsevier]

The authors investigated the influence of normal aging upon equilibrium and kinematics features during a whole-body task. Eight young (23 ± 1.51 years) and eight elderly (74.5 ± 4.5 years) adults reached from a standing position an object placed in front of them on the ground. The authors found smaller Center of Masse (CoM) and Center of Pressure (CoP) antero-posterior displacements in elderly than in young adults. Wrist paths were curved in young but straight in elderly adults. Wrist peak velocity and duration were respectively lower and greater in elderly compared to young adults. However, Principal- Component-Analysis did not reveal differences in angle coordination between the two groups, suggesting so that modifications in equilibrium and wrist kinematics reflect an adaptation process that compensates age-related physiological changes. The authors hypothesized that equilibrium preservation in elderly contributes to wrist kinematics modifications. The authors verified this premise by placing young adults under equilibrium restrictions (reduced base of support) and observing that they reproduced the behavior of elderly adults. The authors propose that wrist kinematics is equilibrium dependent and that such a strategy is included in the motor plan of elderly adults. [ABSTRACT FROM AUTHOR]

Abstract: Here, we address the question of whether normal aging influences action representation by comparing the ability of 14 young (age: 23.6±2.1 years) and 14 older (age: 70.1±4.5 years) adults to mentally simulate arm movements under a varying dynamic context. We conducted two experiments in which we experimentally manipulated the gravity and inertial components of arm dynamics: (i) unloaded and loaded vertical arm movements, rotation around the shoulder joint, (ii) unloaded and loaded horizontal arm movements, rotations around the shoulder and elbow joints, in two directions (inertial anisotropy phenomenon). The main findings indicated that imagery ability was equivalent between the two groups of age for the unloaded arm movements, but better for the young than the older group, for the loaded arm movements. For the horizontal movements, we found better imagery ability for the young than the older adults for both movement directions and loads. Finally, young and old adults showed low (<8%)-temporal variability for both overt and covert arm movements in all conditions. Our findings showed a specific decline of action representation in the aging brain and suggest that internal models of action become imprecise with advance in age. This is not exact to say that there is a severe impairment of motor prediction in old adults as they can mentally represent their arm movements with high-temporal consistency. Finally, we propose that motor imagery could be used as a therapeutic tool for motor rehabilitation in aged adults. [Copyright &y& Elsevier]

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]

This study investigates the effects of error-based and reinforcement training on the acquisition and long-term retention of free throw accuracy in basketball. Sixty participants were divided into four groups (n = 15 per group): (i) the error-based group (sensory feedback), (ii) the reinforcement group (binary feedback including success or failure), (iii) the mixed group (sensory feedback followed by binary feedback), and (iv) the control group (without training). Free throws success was recorded before training (PreT), immediately after (Postd0), one day later (Postd1), and seven days later (Postd7). The error-based group, but not the reinforcement group, showed a significant immediate improvement in free throw accuracy (PreT vs Postd0). Interestingly, over time (Postd0 vs Postd1 vs Postd7), the reinforcement group significantly improved its accuracy, while the error-based group decreased it, returning to the PreT level (PreT vs Post7). The mixed group showed the advantage of both training methods, i.e., fast acquisition and retention on a long-term scale. Error-based learning leads to better acquisition, while reinforcement learning leads to better retention. Therefore, the combination of both types of learning is more efficient for both acquisition and retention processes. These findings provide new insight into the acquisition and retention of a fundamental basketball skill in free throw shooting. [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 effects of electrostimulation training on soccer players. An overview of related previous research is provided, along with details of the experimental protocol. The researchers determined that electrostimulation increased knee extension and ball speed.

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]

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 describe the neuromuscular and perceptual responses to incline, decline or level treadmill exercise.Methods: Fifteen healthy subjects performed on separate days 45 min treadmill exercise at 75% heart rate reserve in a level (+ 1% slope), incline (+ 15%) or decline condition (- 15%). Neuromuscular function of the knee extensors (KE) was assessed before and after exercise. Perception of effort, muscle pain and pleasure were measured during the exercise. Muscle pain was also reported up to 96 h after exercise.Results: At the same heart rate, the decline exercise was performed at a higher velocity. This higher velocity was associated with a higher perceived effort and muscle pain, as well as lower pleasure. Maximal isometric KE peak torque and maximal voluntary activation similarly decreased in the three conditions (~ 15 ± 12 and ~ 4 ± 4%). M-wave amplitude of the vastus medialis muscle decreased in the three conditions (~ - 12 ± 13%). M-wave amplitude of the rectus femoris muscle decreased only after the decline exercise (- 12 ± 16%). Peak twitch torque of the electrically evoked contractions was reduced after incline and decline exercises for both 10 and 100 Hz doublets (- 8 ± 9 and - 17 ± 18%). The Dt10/Dt100 ratio was reduced only after decline exercise (- 24 ± 19%).Conclusion: At the same moderate intensity, decline exercise induced a greater level of muscle fatigue associated with a higher perceived effort and muscle pain than incline and level exercise. Exercise intensity should be carefully monitored during decline locomotion for training or rehabilitation purposes. [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]

An acute bout of aerobic exercise induces neuroplasticity in the motor cortex. Moreover, paired associative stimulation (PAS) is known to induce neuroplasticity in M1. However, the possible influence of the type of exercise on the neuroplastic changes remains unknown. The present study investigated the effects of two different modes of muscle contraction produced during locomotor exercise on changes in corticospinal (CS) excitability. Subjects performed two 30-min treadmill exercises at an intensity corresponding to 60% of their maximal heart rate with either a +10% (uphill) or −10% (downhill) slope. These exercises were followed or not by paired associative stimulation method (PAS 25 ) which consisted of 200 paired stimuli (0.25 Hz, 15 min) of median nerve electrical stimulation followed by transcranial magnetic stimulation of the hand M1 area (ISI 25 ms). Motor evoked potentials (MEP), assessed through abductor pollicis brevis (APB) activity were obtained before exercise, at 5 min, 15 min and 30 min after exercise. A significant (P < 0.05) increase of the MEP amplitude was observed 30 min after both exercises but was not different between the two modes of locomotion. On the contrary, MEP amplitude with PAS 25 increased only 30 min after downhill exercise. We conclude that sub-maximal treadmill exercise increases CS excitability within a period of 30 min. However, the predominant mode of muscle contraction during uphill versus downhill locomotion does not influence CS excitability when assessed using a non-exercised muscle. However, results from PAS 25 suggest that specific neuroplastic changes occur likely due to homeostatic mechanisms induced by exercise plus a PAS protocol. [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.

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]