If I had to pick one thing an adult swimmer can change today and feel in the next length, it would be the head. Not the catch, not the kick. The head.
It is the first link in the chain, and everything behind it sits at whatever angle it decides. Swimmers spend months fixing sinking legs by kicking harder, when the legs were only answering a question the head asked.
What is the correct head position in freestyle?
Your head should stay in line with your spine, neutral, with the waterline crossing around the crown of your head and the eyes looking down and slightly forward.
That is the whole instruction. The neck is not flexed to tuck the chin and not extended to look up the lane. Stand on deck, look straight ahead at the wall, then lie down in that posture and you are close. What should never happen is the head moving up and down independently of the trunk, length after length.
The waterline is the useful check, because you can feel it. Water across the crown and the hairline just under is what I want to see from the deck. Water across the forehead with the eyes clear of the surface means the head is up, whatever it feels like.
Why does lifting your head sink your legs?
Because your body pivots around its middle, so lifting one end drops the other.
You float around the chest, where the lungs are. The legs are dense and hold no air, so they are already trying to sink. Raise the head and you load the front of that pivot, the hips drop to compensate, and you end up dragging your lower half through the water at an angle.
That is the real mechanism behind most sinking legs, which is why the fix so rarely lives in the legs. The longer piece on why your legs sink when you swim covers the other causes, but start with the head, because it is the cheapest one to change.
Does looking down actually reduce drag?
Yes, and it has been measured, though in gliding rather than in full stroke.
In one towing study, ten male swimmers were "towed underwater (at a depth of 60 cm)" at three speeds in three head positions. The authors report a reduction of 4 to 5.2% in average passive drag when the head was down or aligned, with the arms alongside the body compared with head up, and a larger decrease of 10.4 to 10.9% with the arms above the head. Their conclusion: "The swimmer's head location may play an important role in reducing hydrodynamic resistance during passive underwater gliding."
Be careful with those numbers. That was passive towing under the surface, not swimming, so do not expect ten percent off your 100m time for looking at the tiles. What they give you is the direction of the effect: your head is frontal area you control for free.
Brent Rushall's Swimming Science Bulletin from San Diego State University puts the principle plainly: it has been shown that as the angle of the head increases, in relation to horizontal, so does resistance, and "thus, the lower the head angle, the greater would be the streamline." The same bulletin is blunt about the practice: "It is detrimental to streamlining to look forward and/or to raise the head."
Can you tuck your chin too far?
You can, and chin to chest is its own problem.
Burying the face straight down shortens the front of your line, so you lose reach. It makes the breath harder, because the head has further to travel to find air, which usually turns into a lift. And it tightens the neck and shoulders when you need them loose for a high elbow recovery. Neutral means neutral: eyes down and a touch forward. If you cannot tell which side you are on, you are probably high. Almost everyone is.
What should your head do when you breathe?
It should turn, and only turn. No lifting.
The head rotates on its own long axis with the body roll until one eye and the mouth clear the surface, then it comes back, and the lower goggle stays in the water. If the breath feels impossible without lifting, the body is usually not rolling enough to bring the mouth to the air, which is the subject of the piece on body rotation in freestyle.
The SDSU bulletin says the same about the breath: "For effective streamlining, it would be better to rotate the head only on the longitudinal axis even when breathing so that no vertical displacement occurs." Vertical displacement is the polite name for what sinks your legs twice a cycle, and it is why a lifted breath so often ends in a scissor kick.
How does SwimRead read your head position?
Head position is something you cannot see from inside your goggles and anyone on deck can see in one length, which is the kind of gap SwimRead is built for.
Its home page names "Head position" as an example of a focus you can save. It describes the app as a way to "Record a short freestyle video, keep each swimmer's history together, and choose a focus to take into your next practice", and says "The current beta analyzes freestyle filmed from the side of the pool." The capture guide asks you to "Film in landscape from the side, with the whole body visible, a stable camera, standard lens, and normal playback speed", with "10 seconds of continuous freestyle", adding that you "do not need a full pool length". Put breaths in that clip: a head that behaves between breaths can still lift on every breath.
The page is clear about the limits, and so am I. It states that "On-device pose detection estimates up to 33 body landmarks in sampled video frames" and that "These estimates are not validated technique grades". It also says "Video stays on your phone. Technical measurements are sent to improve the analysis."
Which drills fix your head position?
Work the line and the waterline, not the neck.
- Push off and glide five metres, nothing else. Feel where the water sits on your head and where your legs sit. Do it again with the head deliberately up, then neutral, so you learn the difference in your body rather than in words.
- Front kick with a snorkel, arms extended. With no breathing to disturb it, the head has nowhere to hide: eyes down, water on the crown, legs near the surface.
- Single eye breathing. Aim to clear only one eye and the corner of your mouth. It caps how far the head can turn and stops it lifting.
- Tennis ball under the chin, for the chin tuckers only. It tells you straight away if you are crushing your neck.
- Count strokes per length across a few 50s holding the new head position and run the times through the pace calculator. A lower head usually shows up as the same time for fewer strokes before it shows up as a faster one.
Give it two or three sessions before you judge it. A neutral head feels blind at first, because you have been using your eyes to find the wall and now you count instead. That is the only cost, and it passes.
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Head position is the clearest example of why I built SwimRead. It takes one glance from the deck to spot and years to notice on your own. SwimRead's home page states that "SwimRead is free while in beta." If you want to see your own line from the side instead of guessing at it, join the beta.