Friday, March 03, 2006

Swimming Physics 101

There is one general premise to swimming, and that is, you must push the water in a direction opposite to that of the direction you wish to travel. Basic physics here, for every action there is an opposite and equal reaction.

A variety of action-reaction force pairs are evident in nature. Consider the propulsion of a fish through the water. A fish uses its fins to push water backwards. But a push on the water will only serve to accelerate the water. In turn, the water reacts by pushing the fish forwards, propelling the fish through the water. The size of the force on the water equals the size of the force on the fish; the direction of the force on the water (backwards) is opposite the direction of the force on the fish (forwards). For every action, there is an equal (in size) and opposite (in direction) reaction force. Action-reaction force pairs make it possible for fish to swim.

Of course, we are not "swimming" in a vacuum, so other rules of motion and friction come into play. We must also consider the more complex and dynamic properties associated with stroke mechanics, mass and buoyancy as we strive to swim FASTER and more EFFICIENT. To explain this part, what I have found works best is to first off, throw away the physics book and other mumbo jumbo...everyone is different, so keep it simple! Second, our simple goal is to generate as much force (propulsion) as possible, with as little effort as possible! Believe it or not, a good portion of the force we exert while swimming is not transferred to actual propulsion at all, but is lost due to friction, or misdirected due to other factors. Some of the factors which reduce the forces directed towards propulsion we have no control over, but others are directly effected by our stroke mechanics. The 3 most important factors effecting a swimmers force of propulsion are as follows (in no particular order): (1) Body position; (2) Turnover; (3) Leverage. Next month we'll get into the details as to why these 3 factors are so important for the swimmer wanting to go FAST.