Leg fins streamline your whole body to swim faster, whatever your body shape. The more streamlined your body, the less drag and wasted energy. So moving through the water feels more efficient and that helps you to swim faster. They work best for freestyle, backstroke and fly.
Our bodies are all different shapes. But when you look at swimmers in the pool, people with all sorts of different body shapes still look streamlined if they are swimming well. Whatever their body shape, if they are not swimming well then they do not look streamlined in the water. This means we can all improve our body streamlining to swim faster, regardless of our body shape.
Because regular foot fins are on your feet, they sink your whole body down too far in the water. They sink your hips and slope your thighs down. They also make you bend your knees too much. You can feel the extra drag on the front of your body and thighs. So foot flippers don’t streamline your whole body.
Leg fins help you streamline your whole body because they attach to your legs. They help you to swim faster, by better streamlining from your toes all the way up your body. They streamline your whole body whilst you kick. When you swim forwards, the water flow on the fins gently lifts your feet, shins and knees. So your knees become straighter. That lifts your thighs more horizontal too. So your hips straighten and lift higher, to reach a horizontal line with your shoulders. The end result, is better streamlining of your entire upper body and legs along this horizontal line.
It is a chain reaction, triggered by leg fins being on your legs, not on your feet. Even better, with practice, your body remembers this streamlining even after you take them off. So you swim faster without fins too.
Now you can have fins to swim faster and streamline your whole body!
See related FAQ about streamlined thrust throughout your kick.
See all FAQ about smooth forces for faster swimming.