Philippe Dupui

Are there differences in postural regulation according to the level of competition in judoists

The aim of this work was to study the posturokinetic capacities and use of visual information by judoists according to their level of competition. Twenty male judoists aged between 16 and 19 took part. They were separated into two groups: those that competed at regional level and those that competed at national and international level. Static balance was measured on a force platform. No difference was seen between the two groups. However, it seems that visual information is more important to the higher level judoists. Perhaps the level of competition influences the sensory canals involved in balance.

Electrical Stimulation Superimposed onto Voluntary Muscular Contraction

Electrical stimulation (ES) reverses the order of recruitment of motor units (MU) observed with voluntary muscular contraction (VOL) since under ES, large MU are recruited before small MU. The superimposition of ES onto VOL (superimposed technique: application of an electrical stimulus during a voluntary muscle action) can theoretically activate more motor units than VOL performed alone, which can engender an increase of the contraction force. Two superimposed techniques can be used: (i) the twitch interpolation technique (ITT), which consists of interjecting an electrical stimulus onto the muscle nerve; and (ii) the percutaneous superimposed electrical stimulation technique (PST), where the stimulation is applied to the muscle belly. These two superimposed techniques can be used to evaluate the ability to fully activate a muscle. They can thus be employed to distinguish the central or peripheral nature of fatigue after exhausting exercise. In general, whatever the technique employed, the superimposition of ES onto volitional exercise does not recruit more MU than VOL, except with eccentric actions. Nevertheless, the neuromuscular response associated with the use of the superimposed technique (ITT and PST) depends on the parameter of the superimposed current. The sex and the training level of the subjects can also modify the physiological impact of the superimposed technique. Although the motor control differs drastically between training with ES and VOL, the integration of the superimposed technique in training programmes with healthy subjects does not reveal significant benefits compared with programmes performed only with voluntary exercises. Nevertheless, in a therapeutic context, training programmes using ES superimposition compensate volume and muscle strength deficit with more efficiency than programmes using VOL or ES separately.

Do sensorial manipulations affect subjects differently depending on their postural abilities

Objectives: To examine whether sensorial manipulation affects subjects differently according to their postural performance and the strategies used. The literature showed that the level of competition of soccer players influences their postural performance and strategy. Methods: Eight high-level (HL) professional soccer players and nine regional-level (RL) soccer players were tested (1) in a reference condition and (2) in a manipulated sensorial condition (MAN). The MAN condition consisted of perturbing the proprioceptive and exteroceptive information. For each postural condition, balance was assessed by measuring the centre of foot pressure using a force platform during a test of bipedal standing posture. Results: The postural control was less perturbed in the HL than in the RL players in the two postural conditions. Moreover, the group–condition interaction showed that the postural control was less disturbed in the HL than in the RL players when the sensory information was manipulated. Conclusions: The HL soccer players probably possessed a better internal model of verticality than the RL players. Subjects who had a better postural control level were less disturbed by sensorial manipulation than the others in postural regulation.

Short-term effects of electrical stimulation superimposed on muscular voluntary contraction in postural control in elderly women.

Thirty-two women between 62 and 75 years old were randomized into 3 groups. Each group performed a program of 4 sessions a week over 6 weeks. Group SC (n = 11) climbed up and down stairs, group ES (n = 11) practiced electrostimulation, and group SC + ES (n = 10) superimposed the 2 activities simultaneously. Using a force platform and a seesaw platform, static and dynamic balance in eyes-open and eyes-closed conditions were analyzed before and after the programs for each group. After the programs, the results indicated that dynamic balance improved for the 3 groups, but the contribution of visual information in the control of oscillation amplitude was lower in the SC group than in the ES and SC + ES groups. In the SC + ES group, the electrical stimulation interferes with neurophysiologic afference integration in postural control in relation to voluntary movement. Voluntary exercise appears to be more efficient than electrical stimulation and the superimposed techniques to change balancing tactics in the elderly.

Effects of two types of neuromuscular electrical stimulation training on vertical jump performance.

Paillard, T, Noe, F, Bernard, N, Dupui, P, and Hazard, C. Effects of Two Types of Neuromuscular Electrical Stimulation Training on Vertical Jump Performance. J Strength Cond Res 22: 1273-1278, 2008-This study examined the effects of different types of neuromuscular electrical stimulation (NMES) programs on vertical jump performance. Twenty seven healthy trained male students in sports-sciences were recruited and randomized into three groups. The control group (C group, n = 8) did not perform NMES training. Two other groups underwent 3 training sessions a week over 5 weeks on the quadriceps femoris muscle [F group (n = 9): stimulation with an 80 Hz current for 15 min for improving muscle strength; E group (n = 10): stimulation with a 25 Hz current for 60 min for improving muscle endurance]. The height of the vertical jump was measured before NMES training (test 1), one week (test 2) and five weeks (test 3) after the end of the programs. The results showed that the height of the vertical jump significantly increased in both the F and E groups between tests 1 and 2 (5 cm and 3 cm respectively). Results of test 3 showed that both groups preserved their gains. A NMES training program destined to improve muscle endurance does not interfere on vertical jump performance. It can even durably enhance it in the same way as a NMES training program destined to improve muscle strength. Thus, to improve muscle endurance without deteriorating muscle power, sportsmen can use electrical stimulation.

Specificity of the monocular crescents of the visual field in postural control

Postural reactions elicited by monocular visual stimulation in the temporal crescent of the visual field were studied in adult subjects in dynamic balance on a rocking platform. Circular translation of a visual scene was induced in the temporal crescent by the rotation of membrane prisms placed laterally to the stimulated eye. In anteroposterior balance, postural reactions are identical whichever eyes is stimulated: ventral extension of the body when the visual scene moves upwards and dorsal extension when it moves downwards. In lateral balance, postural reactions vary with the stimulated eye: extension of the right side of the body when the right eye is stimulated by an upward displacement of the visual scene, extension of the left side when the left eye is stimulated. This difference, which contrasts with the similarity of reactions elicited by the stimulation of either para-foveal fields, suggests that the most peripheral part of the nasal retina has a specific role in head and body stabilisation.

Posture analysis on young women before and after 60 days of −6° head down bed rest (Wise 2005)

Twenty-four women divided into three groups: control, exercise and nutrition, have been involved in a -6 degrees head down bed rest (HDBR) experiment for 60 days. The objective was to analyse the effects of microgravity on balance function regulation. Group comparisons assessed the efficiency of countermeasures (specific exercises and in particular diet) on the deleterious effects of simulated microgravity. Measurements of orthostatic and dynamic balance were taken 9 and 2 days prior to the experiment, on the first day of getting up, the following day and 4 and 10 days after, under two visual conditions: eyes open and eyes closed. The results confirmed that, as in any other test performed with ordinary subjects, the postural balance performances are better with eyes open than with eyes closed. The static and dynamic postural performances were impaired on the first day of recovery (R0) following HDBR. This impairment lasted up to 4 days after getting up and, afterwards the volunteers recovered their initial performances. The exercise group recovered static postural performances more quickly than the other groups whereas there were no differences in the recovery of the dynamic balance performances.

Caractéristiques des paramètres spatio-temporels de la marche chez l’hémiplégique

© 2018 E physiopathologique des déficits cinématiques, l’incidence des conditions de réentraînement de la marche, et les bénéfices d’un traitement. Cette analyse, complémentaire des évaluations cliniques courantes, met en évidence la limitation des degrés de liberté du mouvement due aux mécanismes de la parésie spastique [1–3] et les mécanismes de compensation dans le membre inférieur non-parétique [1,3]. Conclusion.– Nos résultats pourraient inciter les cliniciens à déterminer les stratégies de coordination motrice, pour définir les traitements réduisant au mieux les anomalies de la marche dans l’hémiparésie. Références [1] Hutin E, Pradon D, Barbier F, Gracies JM, Bussel B, Roche N. Lower limb coordination in hemiparetic subjects: impact of botulinum toxin injections into rectus femoris. Neurorehabil Neural Repair 2010;24(5):442–9. [2] Hutin E, Pradon D, Barbier F, Gracies JM, Bussel B, Roche N. Lower limb coordination patterns in hemiparetic gait: factors of knee flexion impairment. Clin Biomech 2011;26(3):304–11. [3] Hutin E, Pradon D, Barbier F, Bussel B, Gracies JM, Roche N. Walking Velocity and Lower Limb Coordination in Hemiparesis. Gait Posture in press.

A foot-pointing task and spatiotemporal gait parameters during walking in sportsmen.

Unlike many sports, karate imposes pointing to a target with the lower limb. The nature of each sport could influence gait variables of sportsmen. The aim of this study was to examine the pointing accuracy of limb swing and the spatial and temporal parameters of the walking cycle during walking in karate experts (Group K, n=6) compared to accuracy of nonkarate sportsmen (Group S, n=11). The second aim of this study was to compare the influence of this skill on the spatial and temporal parameters of the walking cycle between the two groups. The analysis was performed with a device composed of a gait analysis system (locometer) coupled to a lighted walkway. This system provides a measurement of the motor skill and the spatial and temporal gait during walking. Analysis for the pointing task indicated no differences between the Karate and the Sportsmen Groups during walking. Moreover, neither the spatial nor temporal characteristics of walking differed between the two groups. Karate does not therefore seem to develop motor programs specific to enhanced performance on this pointing task during walking or alter the walking cycle as compared to some other competitive sports.