Sport

Thesis
Football is among the topmost popular sports in the modern world and is characterized as an intermittent, high intensity and non-continuous exercise. However, there is still a lot of debate and uncertainty surrounding the sports physiological requirements as a result of the overemphasis of skills which lead to the neglect of physical fitness, difficulty in scientific study of the sports as well as the conservative training methods that are mainly employed in the development and training of professional players. There has been an evolutionary trend in the professional football such as changes in the roles that players have, a greater frequency of fixtures to play and new tactics and strategies that continue to increase the all round fitness demands for players. This paper thus wishes to explore periodization theory and methodology in the professional training and development of football players with specific focus on physiological perspectives. The research theorizes that the utilization of specialization training that is based on a comprehensive multilateral foundation is the most effective training method necessary to develop a professional football player.

Introduction
Professional football training and development is a process that should be governed by the principles of training. The core objective of these processes is top increase the footballers sporting skills and ultimately hisher level of sporting performance. Professional football training and development has to cover the various performance aspects or components that are normally employed by a player in a match. These include tactical, technical, socialpsychological and fitness training.  In order for an athlete to compete as a professional football player from a physiological perspective, they need to have high levels of fitness so as to cope with the physical demands that the game requires as well as be able to utilize their technical abilities throughout the whole game. As such fitness training is an important part of the professional footballers training programme. The most important characteristic of a football fitness training program is that it should closely resemble match-play as much as possible. As such the main part of the training for fitness exercise should incorporate a football as this has several advantages. Firstly, the players are able to develop tactical and technical skills under similar conditions to those that they will be subjected to during a match. Secondly, this trains the specific muscle groups that are used when paying football. And finally this has been known to provide greater motivation for players as opposed to training without the ball (Ekblom, 1994, p.124).

Type of Training to be applied
The overall development of the player should strike a balance between specialized training and multilateral development. As such, the earlier stages of training and development should be based on multilateral development which mainly targets the players overall physical development. As the player becomes more developed, the component of specialized training specific to skills needed in football steadily increases. As such the trainer or coach should have a clear understanding of the need for each of the two training stages and how the focus from one to the other changes as the player develops (Bompa  Haff, 2009, p. 31).

It is important to incorporate multilateral development in the formative periods of training program that wishes to develop and form a professional footballer. This is because it lays the ground work for the later steps in training that will be more specialized. The proper implementation of this principle will enable the player to have a developed physiological basis that is essential for optimized performance necessary for professional football. This will ensure that the player has a high level of technical mastery as well as the physical preparation that translate to higher performance levels. The coach or trainer should avoid being tempted to ignore multilateral training for specialized training especially when the player becomes technically adept early in the process of training and development as this may compromise the players ability to sustain their optimal physical form once they get into professional football (Bompa  Haff, 2009, p. 32).

A sequential approach to the development of the player that progresses from the multilateral training to specialization is essential as the player matures so as to maximize their sporting potential. The multilateral stage includes multisport skills, some football specific skills and multifaceted motor development. As such the player undertakes a variety of exercises that allows himher to fully develop hisher physiological system. For example, this phase of training allows the cardiovascular, neuromuscular and the energy systems to be activated in a number of ways. It is only when the player attains an acceptable level of development can him her progress to the next phase which involves more specialization. It is important to note that this stage of development does not exclude specificity in its elements of training and on the contrary aspects of specificity of training should be maintained in all the stages of the training and development program although in varying proportions. Thus at this level specialization is minimal but increases in percentage as the player matures. This helps the player to have a foundation necessary for future development and also helps himher to avoid staleness and overuse injury in future training and match-play (Bompa  Haff, 2009, p. 32).

The adoption of a comprehensive multilateral phase in training and development should be capable of ensuring that the player is best suited for a professional career in football. Although the improvement of performance is slow at the beginning it  gradual increases to peak at eighteen or older, an age when the player has reached psychological as well as physiological maturity and can be able to better handle the pressures of playing professionally. It also allows for progressive and consistent performance in competitions as well as a longer athletic career. Overall physiological development as well as a more progressive loading pattern results in fewer injuries for the player (Bompa Haff, 2009, p. 34).

Once the player is sufficiently developed, the training and development starts the specialization phase which is mainly non-unilateral. This training allows the player to adapt physiologically to football. Specific adaptation involves areas such as the metabolic demand, movement demands, muscle recruitment patterns, contraction type and force generation pattern. Also note that the type of training employed has very specific effects on the players physiological characteristics. For example, resistance training has effects ranging from alterations of the neuromuscular system, metabolic or bioenergetics pathways, and the contractile machinery. Conversely endurance training is capable of stimulating both the peripheral as well as the central adaptations, which include the modification of a players metabolic and bioenergetics factors, altering patterns of neural recruitment and stimulating alterations of skeletal muscle significantly. Contemporary research done on athletes has shown that the skeletal muscles exhibit largely characteristics of plasticity in response to different types of endurance and resistance training resulting in the deactivation or activation of the different signaling pathways on a  molecular level depending on the type of exercise the player is subjected to (Bompa  Haff, 2009, p. 35).

The overall fitness training programme should incorporate elements of intermittency, randomness and dynamism. Although this may make the training and development process of professional footballers seem complex it is absolutely necessary so as to condition them to the conditions of match-play. As such the training should involve randomly sequenced physiological processes. This proves to be a challenge for coaches in their quest to condition and develop players. However, players should be involved in training programs that offers specialization that is based on multilateral training at the beginners stage. The specialization phase is characterized by a progressive increase in intensity and total volume of training as well as the degree of specialization. Specialization in simple terms describes exercise training that mimic or parallel movement in football while the multilateral phase describes exercises that develop endurance, speed and strength. Many researchers have suggested that the best adaptation to training and development of a professional football player occur as a result if exercise specific and that utilizes the football and also exercise that is targeted at specific bio-motor abilities but only after a multilateral foundation has been comprehensively developed (Da Silva, Bloomfield  Marins, 2008).

The fitness training and development programme should consider multiple factors so as to cover the various physical performance aspects that are required in football. As such the training needs to be divided into components that are based on specific physical demands that footballers experience during a match. Players experience varying exercise intensity during a training session as well as during matches. As such, the training must incorporate aerobic, anaerobic as wells specific muscle training. These two terms focus on the energy pathways that are dominant when participating in actual activity, either in training or in a match. Anaerobic and aerobic training represent exercise intensities above and below the maximum oxygen intake, respectively (Reilly  Williams, 2003, p.47).

Physiological state necessary for the success of a professional football player
A professional football player covers a mean distance of approximately eleven kilometers in a ninety minutes game. This value is not representative of the total energy requirements on the player during a game since in addition to running a walking, the footballer also has to perform other activities that are energy demanding. These activities include changing direction, acceleration and deceleration, static muscle contraction, jumping, tackling and rising from the ground among others. The total energy expenditure is therefore determined by all the physiological factors in play that affect the footballer. Experiments done on elite players have shown that out of the total energy contribution in the maximal oxygen intake, 70  is derived from aerobic sources (Tumilty, 1993).

As such the training programs of elite players emphasize on training at such average exercise intensity for at least ninety minutes in order to emphasize the players ability to perform intermittent exercise for prolonged periods, in other words, enhance endurance. In addition a professional player should be capable of performing consistently at high intensity, sprint and develop a high power output (force) necessary for single match situations, for example, jumping, tackling and kicking. The basis for optimal performance in these categories is characterized by fitness in aspects of cardiovascular endurance, muscular endurance and strength combined with interplay of coordination by the nervous system. These characteristics determined genetically but can as well be developed through proper training (Spinks, Reilly  Murphy, 2002, p.53).

Factors affecting efficiency in training and developing of football players
Factors affecting the development and training of players include most importantly factors that the coach and the player can influence such as the players physical abilities anaerobic power, aerobic capacity, strengthspeed, agilityflexibility and coordination. Players Technical and tactical skills controlpassing, tacklingshooting, knowledgecreativity and anticipation. Players Psychological factors confidence, motivation, arousal, concentration. The players current status such as injuries being experienced, nutritional levels and psychological stability is also a factor in play during training. Factors that the coach or player do not have control over such as environmental and social factors such as the coach or trainer, family, friends, the climate, playing surface.  Other factors include the gender of the player and the genetic endowment (Reilley  Korkusuz, 2008)

Methodology
Data for this study will be drawn from field work, documentary analysis and both formal and informal interviews. Also previous research as well as official publication from relevant bodies governing football will form the starting point for the inquiry relevant to this research. To understand the best method for training and developing professional football players, field observations will be carried out on three professional academies and three non professional teams in the United Kingdom that carter for youths wishing to join the senior teams. Data will also be gathered in these situations using formal and informal methods (Holmes 1991, p.20).

The data will then be analyses using the comparative investigation of physical education and sport developed by Holmes (1991). This will be with a view to suggest solutions to currently apparent problem and offer future programme improvements to the way training and developing professional footballers is currently practiced (Holmes, 1991,p 27).