Dysfonction endothéliale et risque cardiovasculaire. L’exercice protège la fonction endothéliale et prévient la maladie cardiovasculaire

Aim

To describe the characteristics of endothelial function and to review the biological mechanisms by which physical exercise training stimulates and/or restores endothelial function.

Current knowledge

Endothelial function, via the vasoprotective effects of nitric oxide (NO), plays a pivotal role in health and cardiovascular disease. Endothelial dysfunction has been identified as a major predictor of cardiovascular events. Therefore, endothelial function was regarded as the primary therapeutic target to prevent cardiovascular risk.

Prospects

Epidemiological work provides strong evidence that exercise directly improves endothelial function. Experimental studies have shown that regular exercise improves endothelial function through an increase in NO bioavailability. Exercise may stimulate NO production and/or decrease NO inactivation by increasing antioxidant capacity and/or attenuating prooxidant enzymes.

Conclusion

Current knowledge of biological protective mechanisms of exercise should encourage us to practice regular exercise to prevent and reduce cardiovascular mortality.     

Évolution chez l'homme de l'Insulin-Like Growth Factor-I dans le liquide interstitiel musculaire suite à un exercice en résistance

Introduction

The impact of resistance exercise on the growth of the vastus lateralis was assessed through interstitial microdialysis measurement of free Insulin-like Growth Factor-I at +3 h30, +4 h50 and +6 h after exercise in 4 healthy subjects.

Results

We observed 3 h30 after exercise an interstitial increase in 3 over 4 subjects, and thereafter a progressive decrease. In the mean time, free or total plasma concentrations did not change.

Conclusion

Resistance exercise seemed to induce an early increase of muscle interstitial free Insulin-like Growth Factor-I in order to initiate muscle growth by an autocrine – paracrine way.     

Administration de courte durée de prednisolone et sécrétion d'érythropoïétine

Introduction

The aim of the study is to assess the effects of a short-term therapeutical prednisolone intake on erythropoietin (EPO) secretion.

Synthesis

We studied, according to a double-blind, randomized cross-over protocol, the effects of a 7 day prednisolone intake (60 mg/day) in 10 healthy male subjects on hematocrit, EPO and hemoglobin concentrations. No significant change was found between the treatments (prednisolone/placebo) in the parameters investigated.

Conclusion

In view of the results obtained, short-term therapeutic glucocorticoid intake did not induce any enhancement of erythropoiesis via EPO stimulation that can result in ergogenic advantage during submaximal exercise.     

Effets d'une restriction hydrique et alimentaire prolongée (ramadan) sur la performance et les réponses cardiovasculaires au cours d'un exercice incrémental en milieu tropical chaud

Backgroung

Previous studies showed that maximal oxygen uptake and maximal heart rate were not different during prolonged fasting (ramadan) compared to normal feeding period. However, the effect of ramadan on the blood pressure response during incremental exercise has not been investigated.

Objective

This study aimed to evaluate the evolution of blood pressure during incremental trial in ramadan period.

Methods

Twelve young trained male aged 24 ± 4 yrs participated as voluntary subjects. Their anthropometric parameters, maximal aerobic power and maximal heart were measured in fasting and in normal feeding periods during incremental trial on cycle ergometer.

Results

No significant difference was observed in any anthropometric parameter. Maximal aerobic power of fasting period was significantly less (P < 0,05) compared to normal feeding. Heart rate at rest, at maximal exercise and during a 15 min period of recovery was not significantly affected. Systolic blood pressure of fasting period at maximal power was significantly lower than during the control period (P < 0,05).

Conclusion

Ramadan negatively influences the capacity of maximal power and cardiovascular response at maximal power.     

Sarcopénie,vieillissement et exercice

Aims

Sarcopenia, a reduction in muscle mass, is intimately linked to ageing, but as well to a deficient-protein intake and a reduced physical-activity level. This implies frailty, motor instability, limited-physical performance, more dependence towards other people and more medical-care costs.

Current knowledge

Several metabolic dysfunctions are related to a reduction of muscle mass. Primarily, it seems that protein synthesis is reduced while proteolysis is increased. Muscle-protein synthesis depends on adequate amino acids intake, but also to the action of several signals inducing the activation of new protein molecules; anabolic hormones, neuronal impulses, muscle-membrane signals. Protein degradation is linked to the activation of signal cascades induced by excess calcium and reactive-oxygen species: capsases and ubiquitin systems mainly.

Prospects

Regular physical training involving strength exercise attenuates the muscle-mass reduction by enhancing protein synthesis, particularly during the early phase of recovery with essential amino-acids supply, enriched with leucine.     

Coordination musculaire lors du coup droit lifté chez les jeunes joueurs de tennis

Purpose

The aim of this study was to assess the timing of muscle activation during the acceleration phase of topspin forehand drives in young tennis players.

Synthesis

The activity of six muscles was recorded using surface electromyography during topspin forehand drives in 22 players (9–17 years). The timing of muscle activation was characterized by the onset of EMG bursts during the acceleration stage.

Conclusion

The proximal-to-distal sequential muscle activity was observed for the agonist muscles while the antagonist muscles were recruited at the end of the acceleration stage. This sequential muscle activity was common to all participants whatever their abilities.     

Effets d'une complémentation nutritionnelle en vitamines et minéraux sur la chute de force et les marqueurs biologiques consécutifs à un exercice excentrique chez des personnes âgées

Purpose

The effects of vitamins and minerals complex supplementation on maximal voluntary contraction decrease (FMV) and biological markers following an eccentric exercise at old people.

Method

Sixteen elderly subjects took either placebo (Pl group) or vitamins and minerals (Isoxan Senior, NHS, Rungis, France) (group S) for 21 d before an eccentric exercise and for 3 d after the exercise. The FMV and surface EMG activity (RMS) of the vastus lateralis (VL), vastus médialis (VM) and rectus fémoris (RF) were recorded before (Pre), immediately after (Post), 24 h (Post 24) and 48 h (Post 48) after the exercise. CCVThe creatine kinase (CK), lactate déshydrogénase, malondialdéhyde, and tumor necrosis Factor (TNFα) levels were analyzed.

Results

The reduced MVC (S: 11,2 ± 4,8%; Pl: 17,8 ± 10,4%, P < 0,01) after exercise was associated with a significant reduction in RMS VL, RMS VM and RMS RF values for both groups. A faster FMV recovery appeared at 48 h for the S group (P < 0.05). CK and TNFα values increased in post-exercise.

Conclusion

A dietary supplementation of a vitamin and mineral complex does not attenuate the loss of contractile function immediately after the running exercise, and it may accelerate the recovery of maximal force capacity after 48 h by limiting the post-exercise pro-inflammatory processes.     

Comparison of three types of full-body compression garments on throwing and repeat-sprint performance in cricket players

Objective

To compare the effects of three types of full‐body compression garments (Skins, Adidas and Under Armour) on repeat‐sprint and throwing performance in cricket players.

Methods

Following familiarisation, 10 male cricket players performed four randomised exercise sessions (3 garments and a control). Each session involved a 30 min repeat‐sprint exercise protocol comprising 20 m sprints every minute, separated by submaximal exercise. Throwing tests included a pre‐exercise and a postexercise maximal distance test and accuracy throwing tests. During each session, measures of heart rate, skin temperature, change in body mass, rate of perceived exertion and perceived muscle soreness were recorded. Capillary blood samples were analysed before and after exercise for lactate, pH, O₂ saturation and O₂ partial pressure, and 24 h after exercise for creatine kinase (CK). Ratings of perceived muscle soreness were also obtained 24 h after exercise.

Results

No significant differences (p>0.05) were evident in repeat‐sprint performance (10 m, 20 m time or total submaximal distance covered) or throwing performance (maximum distance or accuracy). No significant differences (p>0.05) were observed in heart rate, body mass change or blood measures during exercise. Significant differences (p<0.05) were observed by way of higher mean skin temperature, lower 24 h postexercise CK values and lower 24 h postexercise ratings of muscle soreness when wearing compression garments. Analysis between respective brands of compression garments revealed no statistical differences (p>0.05).

Conclusions

No benefit was noted when wearing compression garments for repeat‐sprint or throwing performance; however, the use of the garments as a recovery tool, when worn after exercise, may be beneficial to reduce postexercise trauma and perceived muscle soreness.Compression garments are elastic, body‐moulded suits with an engineered compression gradient that can be worn as an upper‐, lower‐ or full‐body piece. Compression garments and elastic stockings have long been used in medicine to assist with venous return and reduce peripheral swelling in vascular patients.^1,2 Relatively recently, commercially available compression garments have been proposed to provide performance benefits to athletes.³ These garments, worn during training and competition to aid performance and after exercise to speed recovery, are suggested to improve peripheral circulation and venous return,^4,5 improve clearance of blood lactate [La⁻],⁶ reduce muscle oscillation⁷ and improve clearance of markers of muscle damage such as creatine kinase (CK).⁸Of late, there has been an increase in the popularity of the use of compression garments across a range of sports, particularly among cricket players. Although a significant body of research evidence exists describing the role of compression garments in vascular distribution in diseased patients, less evidence exists for athletic sports performance. To date, only a small body of research supports the notion that the garments may provide some benefit to sports performance⁷ or aid recovery from exercise.⁸ Currently, several companies have garments for sale, with little performance‐based evidence available to support their use or compare between brands for superior ergogenic benefits. In particular, there is currently no research on the effect of compression garments in improving exercise performance during high‐intensity, intermittent activity such as that observed during repeat‐sprint sports. Further, as previous studies have reported the improvement of performance in singular explosive movements such as a vertical jump,⁹ there is potential to transfer these benefits to improve explosive actions involved in cricket, including sprinting and throwing, as garments are often worn during games.Therefore, the aim of this study was to compare the effects of three different types of full‐body compression garments (Skins, Adidas and Under Armour) and a control condition (no compression garment) on performance in intermittent, repeat‐sprint and throwing performance in cricket players.     

Extension du modèle puissance–temps limite pour estimer la production d’énergie aérobie et anaérobie lors de l’exercice intense

Aim

Examine how the modelling of the relation between power and time to exhaustion can provide an estimation of the production of aerobic and anaerobic energy during intense exercise.

Current knowledge

The hyperbolic model made it possible to define the critical power corresponding to the maximal rate of energy renewed by aerobic metabolism. A new model distinguishing the critical power from the maximal aerobic power has been built to estimate more precisely the anaerobic contribution. Data from middle distance runners and subjects tested on cycle ergometer showed a relative contribution of anaerobic metabolism arising from critical power and increasing until around 10 % of total power when aerobic energy production reaches its maximum.

Prospects

Considering the slow component of oxygen uptake would provide a more precise analysis of energy production and transformation during exercise at high intensity.     

Évolution de l’oxygénation musculaire au début de l’exercice intense en hyperoxie modérée

Introduction

The muscle oxygenation profile determined with the technique of near infrared spectroscopy was used to assess the muscle oxygen utilization kinetics at the onset of exercise.

Synthesis

The mean response time of the muscle deoxygenation increase was not modified by hyperoxia (19.6 ± 2.3 s in hyperoxia versus 20.6 ± 2.8 s in normoxia, NS).

Conclusion

This result suggests that hyperoxia did not induce any acceleration of the oxygen utilization kinetic at the muscle level and that the oxygen delivery to muscle is not the limiting factor of this kinetic.     

Validité et reproductibilité d’un dynamomètre inertiel basé sur l’accélérométrie

Introduction

The purpose of this study was to investigate the validity and reliability of an inertial dynamometer using accelerometry.

Methods

Fourteen subjects were tested during three successive sessions at four increasing loads (30, 50, 70 and 95% of the 1RM). Maximal force, velocity and power performances were simultaneously assessed by the Myotest (Myotest S.A., Switzerland), an inertial dynamometer using accelerometry, and by another control valid dynamometer witch combine accelerometer and linear position transducer. At three first loads, only minor differences appeared in between both dynamometers, correlations were excellent and coefficients of variation were good and similar. However, at 95% of the 1RM, Myotest validity and reliability became insufficient.

Conclusion

Bench press inertial assessment with accelerometer appeared valid and reliable at 30, 50 and 70% of the 1RM, but not at 95% of the 1RM.     

Présentation clinique,biologique et ergométrique de six cas d’overtraining syndrome

Introduction

This work aimed at describing clinical and laboratory characteristics of the overtraining syndrome in its chronic form (staleness).

Summary of facts

We present six cases of chronic overtraining syndrome that have undergone an in-depth survey. Response to the standardized questionnaire for overtraining of the SFMS appears remarkably monomorphic. Patients often exhibit low IGFBP-3 and lower maximal heart rate at exercise, as well as low value of the constant γ2 of postexercice lactate decrease and a lowered ability to oxidize fat during exercise.

Conclusion

Clinical and biological presentation of the overtraining syndrome is highly variable, but the SFMS questionnaire is actually the most relevant approach. Decreases in IGFBP-3 and maximal heart rate are found in agreement with previous literature. A lowered γ2 constant and a “glucodependance” at exercise calorimetry may represent new interesting markers.     

Application du concept de puissance critique à différentes populations

Aim

The aim of this review was to state the use of critical power concept at different populations and to summarize studies reported data in order to highlight its interest for the aerobic abilities assessement.

Conclusion

The critical power determination is based on times to exhaustion at different exercise intensities. The synthesis of several studies showed that this concept allows to discriminate populations relatively to their aerobic abilities. This is confirmed by its correlation to maximal oxygen uptake and ventilatory threshold in age and fitness different populations.     

Aspects biologiques des interactions de l’exercice et de la récupération

Subject

The use of Fourier transform infrared spectrometry technique (FT-IR) as a pitch technique of the biological control of short and intense exercises close to those of Rugby matches.

Material and method

In reference to 28 rugbymen of international level, the biological results of three short and intense exercises and two periods of recovery were analyzed by TF-IR. The exercises are: (1) sprints; (2) 12 × 20 m of swerve running; (3) 6 × 30 s of shuttle run.

Results

Lactate, glucose, urea, and to a lesser degree, triglycerides showed a significant evolution. If the evolution of the two first was in conformity with the literature, the increase of urea probably results from the activation of the purins–nucleotides cycle, whereas the evolution of triglycerides is explained by their probable muscular use during periods of active recovery. Among proteins related to the healthy sportsman, only haptoglobin presents a significant variation difficult to explain whereas CRP, orosomucoid and immunoglobulins A, G and M remain close to their rest values.

Conclusion

With the use of FT-IR technique, it is possible to intervene directly on the pitches of the sporting practice to control the biological incidences and to adjust the loads individually. It is also possible to detect inflammatory and immunological problems related to the biomechanical and physiological stresses.     

30-15 Intermittent Fitness Test et répétition de sprints

Introduction

The maximal running velocity (V_IFT) reached at the end of the 30-15 Intermittent Fitness Tests (30-15_IFT) is very well related to most physiologic determinants of team-sport performance: explosive power of lower limbs, speed, maximal aerobic power and the ability to recover between exercise bouts. Nevertheless, its relationship with repeated sprint ability (RSA) was unknown.

Synthesis of the facts

Present results in 84 team-sport athletes show that V_IFT is very well related to mean sprint time during a RSA test (p > 0.001).

Conclusion

We conclude that V_IFT is highly representative of most physiologic determinants of performance in team-sports, and could thus been used to monitor athletic performance of team-sport players.     

Quelques réflexions à propos des autorisations accordées pour usage à des fins thérapeutiques (AUT)

Aims

In the present paper the critical analysis of the therapeutic use exemption (TUE) system has been performed and propositions has been suggested to ameliorate it.

Current knowledge

One of the criteria of WADA for granting a TUE is that “the therapeutic use of the substance would not produce significant enhancement of performance”. However, all the substances concerned by TUE are on the prohibited list and are able to produce significant enhancement of performance. Unfortunately, it is not possible to know why and how an athlete used the drug.

Conclusion

In order to limit the cheating risk the author recommend a number of accurate rules about the use of TUE compatible with the European convention on human rights.     

Évolution des paramètres physique et anthropométrique de jeunes rugbymen de haut niveau sur une saison sportive

Introduction

The objective of the study is to measure the evolution of the anthropometric and physical parameters in young elite rugby players during one rugby league season.

Results

This study shows an enhancement of the aerobic and lactic anaerobic performances in the first six months of the preparation. Therefore, these aptitudes decrease in April. There is no modification of the lactic anaerobic performance during the season.

Conclusion

This study shows the difficulty to organise the training planification during the winter period for the elite players. The reason for the rugby league season fatigue has yet to be defined and will be the purpose of a future study.     

Analyse de variables permettant la détermination du niveau d'un cycliste

Aims

We aimed to define a mathematical model allowing to foresee the level of a cyclist.

Methods

One hundred (and) six cyclists were classified according to their level and some of their physiological characteristics were measured with the threshold (4 mmol of lactate) and with the maximum values of their oxygen flow.

Results

To the threshold, power, lactatemy, age and size allow to foresee the level with an error rate of 27% ; to the maximum values, the criteria are development, flow in oxygen, lactatemy and age (error rate of 31%).

Conclusion

These results indicate that our mathematical model allows to envisage the level.     

Local thrombolysis for patients of severe cerebral venous sinus thrombosis during puerperium

Objective

To explore and evaluate the efficacy of intrasinus thrombolysis (IST) in patients with cerebral venous sinus thrombosis (CVST) during postpartum period.

Methods

11 patients during postpartum period with CVST who received IST during July 2007–November 2011 were included. Urokinase was infused into the sinuses via a microcatheter. Magnetic resonance venography (MRV) was performed to assess the recanalization of venous sinuses.

Results

Before discharge, the intracranial pressure in 11 patients was under 200 mmH₂O. MRV confirmed that venous sinus of 9 patients were smooth. The cortex venous and deep venous recovered to normal. Venous sinus of 2 patients recanalized partly, and cortex venous and deep venous had compensation. 9 patients had good outcome and 2 patients had only mild deficits.

Conclusion

Intrasinus thrombolysis is safe and effective in patients with severe cerebral venous sinus thrombosis during postpartum period.