3.5. The most common mistake in the front crawl stroke – crossing the centerline

A very common mistake that affects about 9 out of 10 swimmers is placing the hand across the body’s centerline and pulling under the body. The body’s axis runs straight down the center from top to bottom, and each arm should stay on its own side during freestyle.
This mistake starts right when entering the water. If your fingers enter from the side and your arm is still bent, the rest of your body will follow that arm, which causes two things: first, you’ll twist in the water like an eel, and second, you won’t be able to anchor properly because the arm is misaligned and slips away as it curves.
Each hand should “play in its own sandbox,” so when pulling with the right hand:
(1) Enter the water at shoulder width – it might feel wide, but it’s definitely not in front of your head, where most swimmers place it. (2) Reach forward as if to grab something under the surface – that’s where the pull begins – with a straight arm, not bent.
(3) Begin the outer curve of the “S” shape, just slightly rotating the palm outward, about 10 cm.
Pull towards the belly button, but be careful – this is where swimmers often overdo it and pull too far inward, which is extremely inefficient. Pulling too far across twists the body – that’s not what we want. Use your body’s axis as a guide to make sure the stroke never crosses the imaginary midline.
Finally, complete the stroke by pushing the water all the way to the thigh at the surface.
To check, have someone film you from the front and focus on whether your hand enters and pulls across your body. This is a very common mistake and one we often don’t catch unless we see ourselves from the outside.