Dante Dettamanti BS, MS
Coached Stanford University to Eight NCAA Championships
Dry-land strength training is part of the conditioning program of many water polo teams around the world, with the idea being that the stronger you are, the better your performance in the water. A big question that we have to ask as coaches, trainers and players, is strength training necessary to become a better player, or is it just something that has been perpetuated by strength trainers as necessary for all sports? It sounds logical. Get stronger and improve your performance. Is it really that simple? Do the same principals of strength apply in the water as it they do on land?
Let’s start by looking at the sport of water polo, and what parts of the game might possibly need added strength for improvement in performance. I can think of four areas where added strength might be of benefit to the water polo player: swimming speed, leg strength (eggbeater) to get higher out of the water, shooting the ball harder, and the grappling and holding that goes on underwater between two players. In this two-part series we will explore the need (or not) of strength for swimming (Part 1) and the need for strength in leg related parts of water polo, namely getting high out of the water, shooting the ball, and underwater holding and grappling (Part 2).
To swim fast (increase propulsion) you need to be able to generate enough force to overcome drag and propel the body forward. The key factor that explains swimming performance is POWER. Power is the combination of FORCE and SPEED: power = force x speed. Swimming is a sport where propulsion cannot be generated by pushing-off from a fixed point. Instead propulsion is the result of pushing-off from the water. This aspect alone may determine the need for strength to generate force. An example of how power is generated is shown in the figures a) and b) below. In figure a), a swimmer uses his hand to push against a solid object that is anchored to the bottom of a shallow pool. In figure b), the swimmer pushes against the water.
|Figure a) Pushing against a solid object||Figure b) Pushing against water|
In figure a) above, the force generated by pushing the hand against the wall will produce an opposite reaction (Fp, as indicated by the arrow) to move the body forward at a certain speed. In this case, all of the mechanical force that comes from pushing on the wall is transferred to the body. The harder the arm pushes, the more power is generated to push the body forward at a greater speed.
In figure b), the same swimmer pushes back on the water instead of a solid object. A small part of the mechanical force the swimmer delivers helps to generate the power to propel the swimmer forward (Fp, as indicated by smaller arrow). This is because most of the force is converted into kinetic energy of the water (small arrows) rather than contributing to the forward speed of the swimmer. Irrespective of drag, lift, wave resistance etc, the thrust that propels the swimmer forward is generated by pushing a mass (handful) of water backwards.
In other words, the mechanical force generated by the muscles is mostly wasted on pushing the water backwards; whereas all of the force generated by pushing against the solid object goes into pushing the body forward. Consequently, the forward speed of the body generated by pushing against the solid object is much greater than the speed generated by applying the same force to the water.
In the first case (pushing against the solid object), it would seem that increasing the strength of the arm and shoulder muscles in order to generate more force, would be helpful in producing more forward speed. This is because you can push back harder with more muscle strength. In the second case, muscle strength seems to be irrelevant; because most of the force just goes into the water, and does not help that much in propelling the body forward. Pushing back with more force does not help you propel the body forward faster. So, what is the need for stronger muscles if you are pushing back on water instead of a solid object?
As an experiment to illustrate this concept, a swimmer can float on his back on the surface of the water, with his feet facing the pool wall. If the swimmer pushes on the wall with both feet, he will propel himself backwards at a fast speed. Now, have the same swimmer perform a breaststroke kick with the bottom of the feet pushing against the water instead of the wall. The body will move away from the wall; but at a fraction of the speed gained from using the wall.
POWER = FORCE x velocity
Theoretically, when the swimmer pushes against the solid wall, the more force he can generate and the more power he can generate to move away from the wall. The swimmer can gain more force by increasing the strength of the leg muscles; or he can gain more force by using better technique of bending the knees and hips more before he pushes off the wall. Generating more force in the breaststroke kick by increasing the strength of the muscles will not help generate more power; because most of that extra force will be transferred to the moving water, and not to forward thrust of the body.
So, how do we generate more forward thrust when using the breaststroke kick? One way is to improve the technique of the kick, so that more of the surface area of the bottom of the foot is pushing back against the water. The bigger the surface of the bottom of the foot that is pushing against the water. the more water the foot will push back, and consequently the more forward thrust is generated. (More details on breaststroke and eggbeater technique in Part 2).
POWER = force x VELOCITY
Another way to generate more thrust is to increase the velocity component of power (remember that power = force x velocity). The faster you can move the bottom of the foot through the water, the more power you can generate. So, if you can’t generate more power by increasing the force component of the equation, then you need to increase the velocity component of power by moving the leg faster through the water.
This same concept of force and velocity contributing to power also works with the hands while swimming. Increasing the force that the arm and shoulder muscles generate, doesn’t produce an increase in swimming speed, again because of the mechanical energy being dissipated into moving the water backwards. So, in order to swim faster, the swimmer must improve technique so that the palm of the hand moves the biggest mass of water backwards, and at the same time increase the velocity of the arm and hand moving through the water. A big hand surface area pushing on the water creates drag that helps thrust the swimmer forward. New research indicates that drag on the arm and hand is the most important component in creating forward thrust.
LIFT ON THE HAND AND ARM
Besides increasing power, increasing the speed of the arm and hand also increases the lift component of the hand moving through the water, similar to an airplane wing moves through the air. The faster the plane (arm) moves, the more lift is created by the wing (hand) to lift the plane up (move the body forward). Although the “lift” component does not contribute as much as originally thought, it does contribute some to the forward movement of the body. Lift also helps elevate the body upwards as the foot and leg are thrust downward. The lift generated by the foot is also similar to that of an airplane wing.
DRAG - AN AID OR A DETRIMENT TO FORWARD MOVEMENT?
The major contributor to forward movement while swimming is the drag that is associated with moving through the water. This is a difficult concept to explain, but the resistance that is created by moving the arm through the water (drag), helps to propel the body by giving the hand a little more resistance to push against. The more surface area of the hand and foot that pushes through the water, the more drag is created to thrust the body forward or up.
To illustrate the concept of surface area and drag, stand in a shallow pool and pull your hand through the water and down to your leg with your hand flat. Now, pull the hand down to the leg as you were performing a karate chop with your hand turned sideways. You will find that it is harder (there is more resistance) to pulling with your flat hand than with your hand turned sideways. This is because there is more surface area on the palm of the hand than on the side of the hand. The resistance that you feel is "drag resistance". The more drag resistance you have, the more "thrust" you will generate when pulling the hand through the water while swimming.
While the drag on the hand helps create forward propulsion, the drag that is caused by pushing the total body mass through the water can be a detriment to forward propulsion. So while a swimmer wants to increase the drag on the hand and arm to help forward propulsion, at the same time he wants to decrease the drag on the total body that holds him back. Body drag can be reduced by streamlining, and presenting less frontal surface for the water to push against. The swimmer can elongate the body with proper technique, and thus present less frontal surface to the water.
INCREASED DRAG IN WATER POLO
Elongating the body is more difficult to accomplish in water polo because of the shorter swimming stroke and less shoulder rotation involved in swimming with the head up. In order to present less frontal area to the water, and thus reduce drag, it is important for the water polo player to have a strong flutter kick to elevate the hips and feet higher. (See figures c) and d) below.
|Figure c) Normal swimmer||Figure d) Water polo player. Head high, hips|
|less frontal resistance||low. Increased frontal resistance|
BIG BODY, MORE DRAG
Another way to decrease frontal area is to decrease the body bulk that is being pushed through the water. A swimmer with a larger body mass will swim slower than a slim swimmer, because the slim swimmer presents less frontal area to the water. Extra body fat and large muscles contribute to the bigger mass moving through the water; so everything else being equal, the long and lean swimmer and water polo player will present less surface area to the water, and should be able to swim faster. A swimmer or water polo player who puts on extra muscle bulk from strength training, has to weigh the advantages of extra strength (if any) against the disadvantages of increased frontal area.
Another advantage of a long body is long arms that can reach out in front of the body, thus creating more distance to pull the hands back to produce more power. A long body also will produce less drag from wave resistance that is caused by wave turbulence. This happens when the waves produced by the front of the body intersect with the waves from the back of the body. Waves from the longer body have less chance of intersecting each other. The result is less wave drag. Long and lean seems to be the predominant body type that is seen more and more often in both competitive swimming and water polo, for many of the reasons mentioned above.
TRAINING TO INCREASE ARM SPEED
In considering all of the factors mentioned above, it would seem that increased arm speed would increase swimming speed in the water, more so than increasing muscle size and strength. In essence, the swimmer and water polo player are using arm speed instead of arm strength to increase swimming speed. They are increasing the velocity component of power rather than the force component (P = f x V).
So how is a player able to move the arm through the water rapidly, and then do it for a number of times while sprinting up and down the pool? The answer is by training the energy systems responsible for supplying energy (ATP) to the muscles, namely the anaerobic creatine phosphate and lactic acid systems. As mentioned above, the bodies ability to swim fast depends on the velocity of the arms moving through the water. The ability to do this over and over again depends on supplying energy to contract the muscles over and over again. This can only be done by overloading the muscles and energy systems by sprint training, not by making the muscles stronger.
STRENGTH CONTRIBUTION TO SPEED?
The only strength that is necessary is the strength required to move the arm through the water. This can be acquired by performing the event in question (i.e. 20 yard all out sprint swim) over and over again. So, the best training in order to swim faster in the game is to practice swimming fast in practice. Any extra strength that can be acquired from strength training does not contribute to increased speed; so it is not really necessary. Only by training the energy systems responsible for sprint swimming can the water polo player increase the ability to move the arm through the water over and over again at high speed.
As shown above and proven by numerous studies on strength training and performance, dry-land resistance training is not necessary to achieve these results. In many studies performed by sports scientists (Costil D. et al 1983 Swim Technique, Crowe S.E. et al, 1999, Med & Sci in Sport & Exerc., Tanaka H.U. et al, 1993 Med &Sci in Sport & Ex, Sukolovas G, 2000, Olympic Trials Project, Toussaint H. et al. 2001, European Journ. Of Sports Med.), it was found that despite the increases in muscle strength acquired by swim specific dry-land resistance training, these strength gains were not transferred to increased sprint speed in competitive swimmers. Part of the reason is because it has been found, in hundreds of additional studies, that strength training is specific to the activity involved (running, swimming, soccer, basketball, etc). An athlete has to strengthen the muscles in the same way that they are used in the specific sport activity.
As we have discussed above, increased force from stronger muscles just gets dissipated into the water and does not contribute to forward thrust. In most sports activities, whether on land or in the water, the strength necessary to perform the specific activity can be acquired from simply practicing and participating in the sport itself. So, in order to acquire the strength to play water polo, you need to play water polo.
In order to acquire the strength to swim faster, you need to swim fast in training. Any additional training to increase swim speed does not have to come from dry-land strength training; but can come from adding resistance in the water by using stretch cords and performing short, fast and intense practice swims. Increased speed can also come from improving swim technique and from streamlining the body. Technique, streamlining and sprint training become more important than strength in increasing swim speed in competitive sprinters.
A summary of the information presented in this article, and of the numerous scientific studies that have measured and tested every aspect of competitive swimming, including a very recent study (2007) by the Dutch exercise scientist H.M. Toussaint titled “Strength, Power and Technique of Swimming Performance", is that “SWIMMING IS NOT A SPORT REQUIRING MUCH STRENGTH TO SWIM FAST". The bottom line is that only so much strength is necessary to move the arms through the water. That can be acquired by repeating fast sprints in training, and by playing water polo, and occasionally performing resistance training in the water (tethered swimming). This kind of swimming trains the anaerobic energy systems that are used in a water polo game; thus allowing the player to repeat these fast swims over and over again. Adding strength by performing dry-land strength exercises does not add to the swimmers ability to swim faster, or to repeat fast swims over and over again.
[Click Dante's photo to learn more about his water polo experiences and
Click one of the water polo balls to learn where to buy Dante's books.]
WATER POLO PLANET.COM: the Alternative Voice www.waterpoloplanet.com