Propulsion Underwater freestyle pull | air bubbles

Where is the Propulsion greatest during the underwater Freestyle Pull?


Where is the Propulsion greatest during the underwater Freestyle Pull?

I have asked this question for years to some of the most successful coaches and swimmers I know. The answers I have heard are variable. The pulling arm begins to generate propulsion (forces that move the swimmer forward) when the hand is about one foot in front of the shoulder and can continue generating propulsion until the arm runs out of length. Some believe the greatest pulling force is in the front quadrant (in front of the shoulder). Others think the propulsion is greatest in the back quadrant. Still others believe the peak propulsion occurs right at the shoulder, as the hand passes from the front to the back quadrant. Until I had the technology available to measure the forces on the pulling hand (Pressure Meter), I didn’t know the answer, either.

From a purely biomechanical standpoint, it would seem logical that the pulling arm is in its strongest position somewhere near the shoulder, as the hand is moving backwards. As the hand moves through its somewhat circuitous underwater pathway, the arm goes from a negative angle in the shoulder joint to a more neutral or even a slightly positive angle. Those are positions of greater strength. At its midway point near the shoulder, several large and important muscles pull the arm through the water, whether using a high-elbow or deep pulling motion. As the hand nears the end of the propulsion phase in the back quadrant, the Triceps muscles are about the only remaining ones still working, extending the forearm. To determine the strongest point in that pulling path, however, there is more to the answer than just understanding the biomechanics

Another important factor is the coupling energy of the recovering arm, the shoulder rotation and the hip rotation. The kinetic energy of the recovering arm and rotating shoulder usually peak simultaneously, while the hip rotational energy peaks about .2 seconds later. Depending on where the swimmer elects to place more effort, in the rotating shoulder or in the rotating hip, the point of greatest pulling propulsion is affected. Swimmers tend to pull (or push) harder when they concurrently reach the peak angular velocity of either of these two motions. In other words, swimmers have the option of putting more effort into the front quadrant or mid-point of the pull, using strong shoulder rotation, or into the back quadrant of the pull, by pushing harder out the back and by rotating their hip aggressively. 

The correct answer to the question is all of the above, depending on the swimmer and the technique that he or she is using. Below are three good examples of where the peak propulsion of the hand occurs in the front quadrant, at the shoulder and in the back quadrant. 


Zane Grothe reaches his peak pressure (green curve above at yellow line) on the left hand in the front quadrant using a hybrid technique (breathing right). The first green peak is the highest pressure achieved during the propulsion phases. The final green peak occurs during his hand release phase.


With the right hand, Zane reaches his peak hand pressure (orange graph above) very near his shoulder. With both hands, Zane’s peak propulsion occurs nearly simultaneously with the peak shoulder rotation (first peak in pink graph below). The second orange peak above occurs during his hand release phase.