How wide are you opening your mouth to breathe? And are you clamping it down hard when your face is underwater? Two very small details, but two important ones. There’s quite a bit of facial tension caused by both—tension which pervades the mindset and thus the body itself.
Regarding the first point, you don’t need to open your mouth very far to get a good breath. The photo to the left illustrates this. Try it now while you’re at your computer. Barely open your lips and inhale deeply. You still get the air, right? And yet I see countless numbers of swimmers who roll their heads to breathe and what I see is a gaping maw—mouths so wide open it appears they are straining for the last breath they will ever take.
This is usually followed by a tight clamping down of the lips as they seek to keep the water out when the face rolls under. Again, needless facial tension here.
You can keep your lips loosely open as you inhale and loosely open as you roll your head underwater. The positioning of the lips doesn’t have to change at all.
The next time you swim, try to recognize for yourself if you’re indeed doing either of these things or have a friend watch if that makes it easier.
If so, try these movements (inhaling with lips loosely open and rolling head underwater with lips loosely open) at the side of the wall when you’re not swimming. Lay your head in the water sideways, waterline running along your lower lip and goggle and open your mouth just slightly. You can take several inhales here just to get a feel for it. Then, roll your head to look at the bottom of the pool. Usually a small exhale out the nose at this point is good to keep the water out of your nose, but keep the mouth loosely open and relaxed. You can then take these sensations to your whole stroke and try them when you’re swimming.
The topic of breathing is a big one and is something to be covered over the course of several articles, but this will get you going in the right direction.