What does it mean?
Swimming efficiently is important and without it, we probably won’t win a race. Many coaches tend to equate swimming efficiency with speed. They are not the same. Efficiency doesn’t make the most important factor in a swimming race. Speed does.
There are two different ways of measuring efficiency in swimming, which are related but not equal. Mechanical efficiency has to do with how well the velocity of the swimmer is maintained. The more fluctuation in the swimmer’s velocity, the less efficient they are. Mechanical efficiency is governed by the law of inertia. The more the changes in velocity, the more energy it will cost to reach the average velocity.
Physiological efficiency is measured in meters per calorie. Similar to measuring the efficiency of a car in miles per gallon (fuel efficiency), the physiological efficiency simply measures how much energy is expended by a swimmer to swim a certain distance. The less the energy required to swim that distance, the more efficient a swimmer is. Cars are more fuel-efficient on the freeway moving at a steady speed than they are in stop-and-go traffic downtown. The same can be applied to swimming.
There is no simple way to measure the precise number of calories a swimmer expends to reach a given distance, so using physiological efficiency in swimming is not practical. With Velocity Meter technology, however, we can measure the speed of a swimmer and the variation of that speed accurately. Measuring the mechanical efficiency of a swimmer is relatively easy to do.
A swimmer’s efficiency is not necessarily related to his speed. In fact, at higher speeds, swimmers are generally less efficient than they are swimming at slower speeds. Using Velocity Meter technology, we have noted that the differences between peak and trough speeds for freestyle sprinting technique are nearly always greater than while using the slower, distance technique. To become an elite swimmer one cannot be inefficient. Great sprinters swim fast by generating a lot of propulsion (power), while still managing to limit the increase in frontal drag. They also burn a lot of calories. Butterfliers and breaststrokers are far less efficient than freestylers. Backstroke, if swum correctly, is the most efficient stroke of all.
As a coach, it is not my goal to reach maximum efficiency for a swimmer. I am more concerned about achieving and maintaining a swimmer’s highest possible speed for the duration of the race. To help achieve that goal, efficiency is just part of the equation. By using a poor technique, such as overbending the knee, pulling too deeply, holding a poor body or head position, for example, a swimmer will lose both efficiency and speed.
Don’t get me wrong. Fast swimmers must be efficient at all distances. When correcting a swimmer’s poor technique, however, you will not only improve his efficiency. More importantly, you will help him swim faster.
Yours in swimming,