3.4. What is an “S-curve” Underwater?

In the previous video, we learned how deep we should pull, and now we’ll show whether the stroke is straight or if there’s a curve, and whether we pull under the body or away from it.
A small complication for our stroke is that underwater we don’t pull straight, but in a so-called S-curve, meaning there’s a curve in the shape of an “S”. It sounds complicated, but the good news is that most people naturally create this S-curve without even knowing it.
The S-curve is primarily there because it extends the path along which we push ourselves. A stroke along a straight line gives us a path of, let’s say, 1.5 meters, while a stroke along an S-curve gives us 2 meters. As I said at the beginning, the arms are the primary driver of forward movement, and only the underwater path moves us forward, not the above-water path. For this reason, we try to make the underwater path as long as possible and the above-water path as short as possible. Of course, it must still be within some framework of efficiency—it’s not at all effective to go in a huge arc from left to right—but there is a certain shape of the S-curve that will allow us to go much further on one stroke than a straight line or an exaggeratedly chubby S-curve.
The S-curve looks like this: at the beginning of the stroke, which starts roughly at shoulder level, we catch the water by tilting our palms outward, trace an outer arc, then pull the stroke inward toward the body under the navel, which is the second arc of the S-curve, and finally push the palm completely outward behind the thigh.
Once more: extended arm at shoulder level, I begin the outer arc, turn inward under the navel, and push outward. And with the other hand, it’s exactly the same, but mirrored. If I do both movements against each other simultaneously, it creates a kind of keyhole shape.