Wednesday, 19 September 2012

Science of Training in Soccer

Everybody concerned with the game of association soccer (football) realizes that training is a necessary part of preparing for competition.Playing soccer itself is only one part of that preparation. There is a requirement to be fit to play, to work on correcting physical deficiencies and enhance individual strengths.

The basic purpose of training is to improve human capabilities in all their manifestations. These capabilities are characterized in physical, physiological, psycho motor and psychological attributes. Their maximal expression, for example in fitness assessments, comprises limits to human performance, and training programs must therefore be designed to raise these functional limits. The player may be deemed to be adequately fit when he or she has the capabilities to meet the demands of match-play in all its aspects Further improvements in fitness will enable the player to operate at an even higher level of performance and match tempo.

     The ideal level of fitness is arguably never achieved. Athletes always strive to improve, to push their limits as far upwards as possible. As soccer makes demands on the majority of the body’s physiological systems, fitness for the game includes many factors besides competence in game skills and tactical awareness. A key aim in fitness for soccer is to enhance or maintain fitness in areas of strength while correcting weaknesses. In this way the goal of securing an optimal combination of fitness measures can be realized. 

The process of training takes place in a dynamic context where short-term goals may change, often on an irregular or unanticipated basis. At the early stages the immediate aim may be to become fit enough to train more intensively, the more strenuous preparation later being orientated towards match-play. This situation may apply after a long recess or absence through injury. During the rehabilitation period a systematic program of exercise is first needed before the individual can train again with the ball. The recovery process entails recurring cycles in which training is stepped up on a planned basis until the individual is ready to be integrated into team training.

     If vigorous exercise is undertaken too early in the normal training process, the player may be unable to cope and might even incur injury. As a result he or she regresses rather then improve. Even a well-trained individual may be overloaded too far and eventually succumb to injury if there is insufficient time for recovery between strenuous training sessions. The key to effective training is to experience the appropriate training stimulus at the right time. Some of the principles in doing so are now outlined.

Fundamental Concepts:
A basic principle of training is that the biological system to be affected is overloaded. The training stimulus or stress presented is greater than that which the individual is normally accustomed to. Otherwise there is no requirement for the body to adapt and force the occurrence of this adaptation process.

Adaptation entails functional changes in the skeletal muscles and other tissues that have been engaged in exercise. At molecular level the exercise stimulus switches on signal transduction processes that activate intra-cellular responses. Genes carry the genetic information encoded in DNA to build proteins and mRNA for several metabolic genes are acutely elevated after a single bout of exercise. Alterations in ultra structure occur concomitantly with recovering from the session inducing overload As physiological adaptation takes place, the training stimulus is more easily tolerated. For fitness to improve further, the training stimulus must be raised to a new level for a renewal of the overload principle.

        It is clear therefore that the training process is progressive and goes through a spiral of overload – fatigue – recovery – adaptation. If the training is progressed too quickly, ‘ over training’ may be the result. This state is one in which performance falls rather than continues to improve. It can also be induced by training too much at any stage. The concept of progressive overload was accepted from the time of the ancient Olympic Games. The fabled Milo of Croton gained his strength by regularly lifting a growing calf over his head each day. The improvement in fitness over time is not a linear process. The greatest improvements in fitness accrue during the early stages of a fitness training program. Gains become increasingly difficult to obtain as the tissues approach their theoretical limit of adaptability.

The law of disuse indicates that the fitness of the organism deteriorates if it is not regularly subjected to load. Gains in fitness are reversed if the training stimulus is too low, if the athlete has incurred injury or training is abandoned during the off-season period. Gradually the physiological adaptations acquired through strenuous training are lost as ‘de-training’ sets in, although the rate of loss may be less than that at which gains were acquired. Without exercise skeletal muscles atrophy and the bones of the skeleton lose mineral content and become weakened. Some physical activity during detraining and recovery from injury helps to reduce the fall in fitness level and eases the later return to fitness training. The principle of specificity suggests that training effects are limited to the pattern of muscular involvement in the conditioning exercises that are used.

    Different types of motor units exist within skeletal muscle so that a given type of exercise recruits a specific combination of motor units best suited to the task in hand. Training programs for soccer should, whenever possible, be related to the demands of the game. In some instances training can be designed for players to work ‘with the ball’. In other instances, for example in training the strength of the hamstrings or abductor muscle groups, it is necessary to isolate the muscles for specific training.

The principles of overload, reversibility and specificity contain a framework for designing and regulating training programs. Their operation at a generic level provides an understanding of how continuous adaptation is achieved. At the outset individuals will differ in their capabilities due to genetic factors. They will also vary in the extent to which these capabilities can be improved in training.The trainer’s quandary is how to tread the thin line separating optimum physiological accommodation from unwanted harmful overload and a failure to adapt.

The training stimulus:
The effects of training depend on the physiological stimulus provided by the exercise undertaken. The dimensions of exercise are its intensity, its duration and its frequency. A consideration relevant to these factors is the type of exercise performed. The intensity of training is sometimes referred to as its quality. It may be quantified in physiological terms, depending on the type of training. 

Aerobic training may be expressed as a percent of maximal oxygen uptake or as a percent of maximal heart rate. Alternatively it may be characterized as, corresponding to, or exceeding the ‘anaerobic threshold’. The rating of perceived exertion is a subjective means of indicating the severity of exercise. The lactate accumulating in the blood provides an index of the intensity of ‘speed – endurance’ training. For strength training the intensity may be gleaned from the %X-RM, that is the percent of the maximum load (repetition maximum or RM) that can be lifted x times.

 The duration of training is expressed in minutes, especially appropriate when the exercise is continuous. Equivalent alternatives would include the overall work done or the distance run. Intermittent exercise is best broken down into exercise to rest ratios and number (and duration) of repetitions. The length of the intermissions between sets of repetitions should also be prescribed. For example, a session of weight-training may include 3 sets of 6 repetitions of 6-RM (100%) with 3 min between sets whilst an interval training session might be 6-times 600 m with 3 min in between each run.

The frequency of training refers to how many separate training sessions are undertaken each week. These may include sessions twice-a-day at certain parts of the competitive season, especially during the pre-season period. Fewer sessions would be expected at times when the competitive calendar is congested with fixtures. These training dimensions are not entirely independent as they interact with each other. Intensive training cannot be sustained for as long as say skills training at relatively low intensity. Low-intensity work promotes a preferential use of fat rather than carbohydrate and can therefore have a role to play in implementing a weight-control programmes in conjunction with a dietary regimen. High-intensity training can make demands on the body’s energy systems and on its connective tissues, and so activity needs to be varied on consecutive days to allow these systems to recover. Altering the type of exercise can permit the stressed areas of the body to be rested while other areas are overloaded. An example is where speed – endurance running on one day is followed by training in water or deep-water running on the next day. Similarly a morning session may consist of conventional soccer skills and training drills with the ball whilst the afternoon session might engage trunk and upper-body muscles in strength-training. Players with lower-limb injuries may continue to train the upper body, and maintain aerobic fitness by use of cycle ergomcycle ergometry or exercises in water. In these ways a reversal of fitness is prevented while recovery processes are taking place. e try or exercises in water. In these ways a reversal of fitness is prevented while recovery processes are taking place.

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