mardi, 07 juillet 2015 00:00

Entraînement d'endurance aérobie

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Le meilleur moyen d'entraîner la capacité d'endurance aérobie est l'entraînement d'endurance aérobie, également appelé entraînement d'endurance extensif. Cette forme d'endurance est la propriété physique qu'un triathlète doit développer parce qu'elle sollicite au maximum les réserves lipidiques et constitue la base des autres entraînements plus intensifs. La capacité d'endurance aérobie d'un athlète est souvent exprimée par rapport à sa consommation maximale d'oxygène (VO2max). Ce paramètre indique la quantité d'oxygène pouvant être absorbée dans les tissus (essentiellement les muscles actifs), lors d'un effort maximal.

mardi, 07 juillet 2015 00:00

L'entraînements endurance rythme (cyclisme)

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Les entraînements endurance-rythme sont des entraînements qui s'effectuent dans la zone du seuil anaérobie. Ils se fondent sur des répétitions d'une durée comprise entre 5 et 15 minutes. Il s'agit d'entraînements intensifs qui favorisent la filière énergétique assurée par la combustion des glucides. De plus, ces entraînements améliorent le seuil d'endurance, ce qui signifie que l'athlète apprend à pédaler à une allure plus soutenue sans « aller dans le rouge ».

mardi, 07 juillet 2015 00:00

les sensations subjectives en Triathlon

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Si vous voulez améliorer vos performances, vous devez déterminer avec précision, l'intensité d'entraînement correspondant au type d'entraînement que vous voulez faire. En d'autres termes, si vous souhaitez effectuer une séance d'endurance très extensive à vélo ou en course à pied, vous devez également savoir à quelle allure (soutenue ou lente) vous devez rouler ou courir, pour obtenir l'effet d'entraînement escompté pour ce type d'entraînement. Comme une séance de type extensif sollicite plus particulièrement la filière lipidique, une allure trop soutenue solliciterait également la filière des glucides. La détermination précise de l'intensité d'entraînement est également importante.

Endurance sports are activities which are performed during longer time interval and which prevailingly use aerobic metabolism involvement. Aerobic metabolism prevails during physical exercise which is longer than than 2-3 minutes at a low, middle or submaximal intensity load. Exercies used are usually locomotions or repeated cyclic movements. Many scientific works proved that aerobic endurance may last for a longer time before fatique appears and that it can last even in the state of fatique. Also recovery rates are highly related to quality of endurance abilities and faster recovery allows the athlete to shorten rest intervals within and between training sessions and increase overall training load.

The most recognized model of endurance abilities physiology is the Cardiovascular/Anaerobic model, initially suggested by British physiologists A.V. Hill and associates in the mid-1920s. This model basically posits that a lack of oxygen in working muscles is what ultimately limits exercise performance. The cause of fatigue is primarily in cardiorespiratory system and utilization of oxygen. Most adherents to this model use the terms of VO2max, lactate threshold, and running economy when discussing aerobic or endurance training or physiology. Thanks to the new knowledge’s from this field of exercise physiology were made several new models from various points of view, e.g Neuromuscular fatigue model, Muscle trauma model, Biomechanical model, Thermoregulatory model, etc. Every of these models have wanted to supplement the initial model of Hill. The most complex revised physiological model proposed Nakes (2002) as a Central Governor Model. He draw from the original cardiovascular anaerobic model and four additional models that regulate short-time, maximal or long-time submaximal exercise. The basis of this idea is that fatigue is caused by CNS, which is not able to activate muscles to following activities or activities on a desired level. The brain protects the body by regulating power output during any form of exercise with the ultimate goal of maintaining homeostasis and protecting life. Muscle fibre power output is not regulated by factors in the muscle itself but in the brain based on continuous information from senses of the whole body. Fatigue is a relative process and as a consequence of it the exercise intensity is constantly changed during exercise as the brain either employs additional fibres to increase power output or to decrease fibre activation to adjust power output (energy) based on its calculations.

The following is an example of the features of peri­odization that may encompass a typical 14-week swim­ming preparation fora national championships or ma­jor international meet.

Macrocycle 1: aerobic (weeks 1-4)

As in most training programs the initial phase involves the development or reestablishment of endurance fitness. This serves as the basis for the subsequent de­velopment of aerobic and anaerobic capacities and the functional utilization of these capacities. Functional utilization refers to increased swimming speed at a given metabolic load. Apart from the underlying phys­iological adaptations, improved endurance will lead to an increased ability to cope with fatigue and more rapid recovery from the stresses of speed training and competition. In particular, the aim is to develop the capacity and efficiency of the cardiorespiratory sys­tem.

This process is largely achieved by high volume­low intensity training. Other adaptations include increased utilization of fat as a fuel source, stronger ligaments, tendons and connective tissue, adapta­tions within slow-twitch muscle fibers, and improved neuromuscular control. The length of this phase will depend on several factors (e.g., fitness level of ath­letes, time available, objectives of mesocycle) but is normally between 3-4 weeks.

Triathlon has become the most popular multidisciplinary athletic event over the last decade, with competitions performed over a variety of distances, ranging from the triathlon 'sprint' (750m swim, 20k cycle ride, 5k run) to the gruelling Ironman, culminating in a marathon run. Unsurprisingly, therefore, a significant amount of new research is being devoted to investigating the determinants of successful triathlon performance.

Most research to date has focused on the cycle-to-run transition, since significant correlations have been reported between cycling or running time and overall triathlon performance. The influence of swimming on subsequent cycling time has been relatively neglected.

However, a new study from France has demonstrated that swimming in drafting position can significantly improve subsequent cycling efficiency and might therefore be expected to improve triathlon performance in general.

The researchers had shown in a previous study that decreasing the metabolic load during a 750m swim by using a wet suit resulted in a 11% decrease in swimming heart rate and led to a 12% improvement in efficiency during a subsequent 10-minute cycling exercise when compared to swimming without a wet suit. The lower relative intensity when swimming with a wet suit is classically explained by a decrease in 'hydrodynamic drag' resulting from increased buoyancy.

The purpose of training programs in swimming is to produce metabolic, physiological and psychological changes that allow swimmers to perform better in competitions. In swimming, as well as in other sports, aerobic endurance is one of the most important components of the physical fitness of swimmers, while VO2max represents the most objective measure for its assessment. VO2max refers to the maximum amount of oxygen that an individual can utilize during a one-minute exercise. Measurement of VO2max in swimming can be done in three ways, always using a method which is most similar to the swimming conditions during training and competitions. VO2max can be expressed in absolute and relative values, and in the case of elite swimmers ranges from 66 to 80 ml O2/kg/min. According to VO2max values, the work intensity in swimming can be optimized through exercise heart rate and subjective feelings of fatigue. Apart from VO2max, it is very important to measure the percentage of maximal oxygen uptake (%VO2max), which is the highest level of performance that an athlete can maintain over a longer period of time without becoming fatigued. In order to develop and increase VO2max, as well as other factors that influence the development of aerobic or cardio-respiratory endurance, it is advisable to take advantage of endurance training. This type of training can be divided into three levels: basic endurance training, anaerobic threshold endurance training and training above the anaerobic threshold. All three types of training influence the development of resistance, but it is considered that training at the anaerobic threshold is the most significant. Adaptations to training that increase maximum oxygen consumption can be divided into two groups; the first group increases the amount of oxygen that is supplied to the muscles, while the other increases oxygen utilization by the muscles. The latest studies presented in this paper indicate that the prediction of the results and success in swimming, according to the values of maximal oxygen uptake and the impact of training, will always be current in swimming. A single component of success in swimming is rarely the subject of research, in most cases it is usually an entire group of them. Therefore, the aim is to find and develop those factors (characteristics and capabilities) which contribute to the sport results of swimmers.

The tapering strategy used by many swimmers to opti­mize competition performance has been defined as "a progressive non-linear reduction of the training load during a variable period of time, in an attempt to reduce the physiological and psychological stress of daily training and optimize sports performance" (Mujika & Padilla 2000). The aim of the taper be­fore the main competitions of the season is to elicit substantial improvements in performance. These per­formance gains have been variously attributed to in­creased levels of muscular force and power (Trappe et al. 2000), and improvements in neuromuscular, hematological, and hormonal function, and/or the psychological status of the swimmer (Mujika & Padilla 2000).

There are different manifestation of speed in training, e.g. the speed of a sprinter in a 100-meter run, reached javelin release speed, maximum speed of the starting run of the athlete in a long-distance jump, the speed of changing position of the middle player from the middle part of the net into side area, break-free with the ball in basketball etc. Sports performance is conditioned by performing a given movement with maximum speed possible. External manifestation of the resulting speed of both cyclic movement and single-speed movement are always related to as fast carrying out of the movement as possible along defined specific track through muscle contraction. The specificity of movement is given by specific skill in the sports discipline. Manifestations of speed in sports are always characteristic in their maximum intensity. Acyclic movement (throws, casts) can be performed against slight resistance (up to 20 % 1RM). Cyclic movement (sprint) is usually performed without resistance without any significant change is direction. During cyclic movement, a significant change in direction can occur accompanied with decrease and subsequent increase in speed and movement frequency (movement of player with the ball in handball). In this case, it is specific manifestation of speed which is called agility. As far as the duration of the performance of specific motor activity is concerned, it is speed up to 15 seconds (duration exceeding 15 seconds is speed endurance). An independent part of speed abilities is represented by the scope of reaction speed. Reaction speed is manifested by speed as a reaction to a given stimulus (e.g. reaction to start-up shot in 100-meter sprint) and it is understood as time lasting from stimulus to the start of motor activity.

Speed can generally be defined as an ability to reach high speed and frequency of cyclic, single-speed (acyclic) or combined movement through muscle contraction.

Training strength ability sportThe ability to resist external resistance with muscle contraction represents a basic principle of developing the complex of strength ability. Muscle contraction is conditioned by many factors. If there is no visible movements of body segments during muscle contraction, this is referred to as static strength (e.g. holding tim in squat when thighs are held horizontally to the ground). On the other hand, if muscle contraction causes a visible movement of body segments by stretching (excentric muscle contraction) or by shortening the muscle (concentric muscle contraction), it is referred to as dynamic strength (e.g. mutual movement of forearm and upper arm during benchpress exercise). The dynamic strength can further be divided into partial manifestations of dynamic strength:

Maximal strength is manifested by overcoming high or even limit external resistance at a slow speed with a specific muscle group usually in one repetition (e.g. in benchpress).

Explosive strength is manifested by overcoming low external resistance or weight of own body with maximal acceleration in single (acyclic) movement of participating segments (e.g. in throws, or take-offs).