As in many sports, swimming technique is most important to performance. The smooth and perfect in the process of movement, whether stroking through the water, lifting weights or swinging a club, relates to enhanced performance and decrease in change of injury. (Riewald 2003). To swim fast, a swimmer must engage in a constant battle of trying to maximize the propulsive force he experiences. Swimmers adopt many different techniques in an attempt to accomplish this feat; sometimes these techniques are good, other times not so good. Technique also plays a role in injury prevention, as poor mechanics often place stresses on joints and structures in the body that they were not meant to handle. (Riewald 2003)
2.2 Components of Swim Performance
The factors that can influence swimming performance can be classified into three categories which are the psychological factor, physiological and biomechanical factor. The psychological is the main factor that contributes to swim enhancement of performance. The field of physiological and biomechanical also makes up a huge portion to influence swim performance. These complex areas are important to be study in order to establish a meaningful relationship of speed and power in swim performance.
2.3 Physiology of Swimming
For the past 30 years, the physiology of swimming has been explored extensively. Many areas of the physiology contribute to several studies. Swimming, like other forms of exercise, involves the muscle contraction that results in a desired motor output. In order to produce a movement, skeletal muscles must stimulate via nervous impulse. Muscular contraction causes by this impulse. While the movement of the joint results from the muscle pull on bone structures. In swimming, these movements if often occur especially among competitive swimmers (McArdle 2003).
The studies of physiology on competitive swimmers become popular after the 1960aa‚¬a„?s (Lavoie, 2004). The study begins to focus on association between energy expenditure and velocity. At that time, it belief that a exponential relationship existed within energy cost and swimming velocity. Later, Montpetit (2001) discover that this is actually a linear relationship. Lacour (2003) reported that the energy cost of swimming is closely depended on swimming technique, body size, swimming velocity and level of performance. It concludes that as resistance increases, swimming velocity will also increase. This major discover demonstrates that the importance to overcome resistance physically over a given distance in a certain period of time.
Nervous system and muscular force is other physiological factors that important to swimming performance. The nervous system plays an important role in swimming performance because it helps to determine how quickly and forcefully a movement takes place. It is also the precursor of the movement. As a swimmers practice the same movement repeatedly, it become an adaptation and the movement pattern is remembered by the brain. The result or the end of the practice is an increase in the efficiency of the movement. Due training, it can improve the force of movement by causing an increase in the recruitment of motor units (Katch 2006). The larger motor units recruited, the more muscle fibers will be contracted. Contracting muscle fibers will increase systematically as the muscle force increases. Training can cause increased innervations to a group of muscles which can improve speed of contraction and recruitment of muscles (Maglischo 2003).
Proper nervous stimulation and size of the muscle will produce the muscular force. Specific type of training can cause increase the size of the muscle or better known as hypertrophy and thus more powerful strength can be produce via motor output. This absolute strength is determined by its cross sectional area (Zatsiorsky 2005). The larger the muscle, the greater the force produced. However, increase in the muscle size and muscle mass also can have adverse effects on biomechanical of the swimmer which by the increasing contractile force at certain level. It is a serious matter to look upon when considering the training especially to the competitive swimmers, to well known of how much strength that increases will be beneficial and not beneficial to them. Since the two components of power are strength and speed, it is vital focus to improve strength in order to create potential of more power.
2.4 Biomechanics of Swimming
Biomechanics is interesting area of study because this area of study shows much potential to enhance the swim performance. 10% increase in swimming technique provided increase over a range of performance rather than maximal aerobic and anaerobic power (Toussaint and Hollander 2004). Toussaint and Beek (2002) reported that the success for competitive swimmers relies on swimmers aptitude to produce force and to decrease resistance which to encountered during forward movement in the water.
Logically, water is denser than air. Therefore, swimmers will encounter more resistance when attempting the movement. Besides that, as the rate of velocity decreases, there is a proportional decrease in the resistance of the water. Resistance of the water is at the top area of the swimmers that against water as the body move through it. Drag, is the motion of resistance to the swimmers. (Malinlisho 2003). There are two type of drag which are passive and active drag. Passive drag is described as the resistance on the swimmers body in a static position (Chatard 2000). While active drag is the resistance of water that against the moving body. Measurement of the active drag is reported slightly higher than passive drag (Kolmogorov, Rumyantseva, Gordon & Cappaert 2007).
It is important to note that of the two types of drag, passive drag cannot be altered and it is constant speed, but increases a higher velocity. Passive drag is an important factor in the speed of the swimmer from a start or a turn off of a wall. The less passive drag a swimmer has, the more slowly they will lose momentum. Passive drag is related to the frontal surface area of an individual. Passive drag has been reported to be a factor that can contribute to the prediction of swimming performance (Chatard and Lacour 2000).
Velocity of swimming has been associated with drag, power input and power output (Toussaint & Beek 2002). Active drag can be modified on efficiency based on technique of swimming action (Toussaint 2002). Clarys (2003) stated that predominant factor in active drag was the swimming technique. It also stated that measurements of active drag on elite swimmers are lower than non- elite swimmers. While study by Kolmogorov (2007) reported that active drag for freestyle was less compared to breastroke swimming. It also reported that mechanical power output for skilled swimmer is lesser than mechanical power output in less skilled swimmers. This assumed because of the cost of swimming for an elite swimmer is much lower than a non-elite swimmer.
The more biomechanically efficient a swimmer is, the less energy requires swimming at faster rate of speed (Toussaint 2002). Further, as increase in velocity, the resistance of the water will also increase. Swimmers with more active drag have to produce more force on the water to go a certain speed and vice versa. (Maglischo 2003). The level of the athletes, anthropometric measures, velocity and swimming efficiency are related to the cost of swimming. These costs are similar either in men neither women that given similar relative measures (Chatard 2001) Chatard (2000) also stated that passive drag is determining by the frontal body area which can influence performance.
Other factor that is related to the biomechanics of swimming is the length of the swimmer. Larsen, Yanchen and Baer (2000) reported that, having length is one of the reasons why successful competitive swimmer is taller in height compared to others. Length of the swimmer will lesser their drag in the water. Further, successful swimmers achieve greater distance per stroke than less skilled swimmers (Craig 2005). Distance per stroke and stroke rate somehow is controlled by swimming velocity. Distance per stroke is best defined as the distance traveled in the water by a swimmer with each arm pull. And stroke rate is frequency of how fast the arms can move. Faster swimmers in freestyle had a longer distance per stroke and maintaining a slower stroke rate (Craig and colleagues 2005).
An experience swimmer can control their speed by maintaining certain distance per stroke in increasing stroke rate or in maintaining stage. It has been described above that the length of a swimmer having less drag is apparent with the longer distance per stroke also spent more time with their arms outstretched. This action will influence drag for a short period of time due to increase of the swimmer length. Furthermore, it is important to know that power is an important determinant in enhancement of swimming performance. There are two components of power which are the speed and force. Swimmer will not have the ability to produce as much force on water if they move their arms too quickly. It clearly shows the relationship between stroke rate and the optimal distance per stroke.
2.5 The Relationship of Power to Swim Performance
Power is classified as one of five determinants of swimming performance, and the others are metabolism (power input), drag, propelling efficiency and gross efficiency (Toussaint 2002). Specifically, power can be defined as Power = Force x Velocity (Harman 2004). Many investigators have noted the importance of power that demonstrated a positive relationship between power and sprint swim performance (Bradshaw & Hoyle, 2003).
Christensen and smith (2007) reported that power measured is a significant contributor to swimming performance and that sprint speed that is related to stroking arm force. Sprint swimming performance influences by the ability to produce power in an efficient manner and utilization of power specifically in the swimming action. (Costill 2003). Costill (2005) later discover that improvements in swimming were found strongly related with power production, both in measures of power in the water and on land. Sharp (2006) suggested that the ability to produce power plays a positive role in swimming performance if swimmer undergo specific training that can increase power. The peak swimming power is significantly correlated with sprint swimming velocity (Boelk 2007).
Powerful Swimmer is often faster (Malischo 2003). He suggested that swimming with specific training technique will increase power. These technique, are performing in short duration with high intensity bouts of swimming where the focus on producing the most powerful movement with the correct form. For some swimmers, power training may be beneficial and most important type of training (Bompa 1993). He concludes this by establishing a relationship between power and the importance of being able to maintain the increased power throughout the race.
2.5 Methods to Increase Power
Plenty types of training that can be employed to improve power. Most of the swim coaches use specific swimming exercises, such as all-out sprints for a short distance to improve swimming power (Maglischo 2003). Other types of training that have shown increased power production include dry land exercises such as weight training and plyometric training (Bompa 1993).
In contemporary swim training, the training program for competitive swimmers often includes dry land exercises. In comparison to the load during actual swimming these exercises should provide a greater resistance to the working muscles and hence increase maximal power output more effectively. However, as indicated earlier, the body adapts to adequately cope with the specific forms of exercise stress applied. This adaptive process is rather specific requiring for example that movement pattern during the strength training is similar to that during competitive swimming. It is known for quite some time that the movement patterns of the different swimming strokes are difficult to reproduce outside the water and thus any training effect may only partially, if at all, carry over to the competitive performance (Toussaint 2007)
Propelling muscle is where the power output delivered by swimmer. In this propelling muscle, mechanical power are converted from the aerobic and anaerobic power input. (Toussaint and Beek 1992)