Our body is an amazing machine which can adapt to almost anything. However, if you want to keep it working smoothly for a long time, it is better to make it work the way it is intended to, in complete balance and alignment or in its natural way. Most physical therapists and chiropractors are spending countless hours trying to repair the damages done by the incorrect uses of some part of our bodies. In swimming, the water is supporting your body, which helps to alleviate some of the damage. But often the problems with the shoulder joints can easily be alleviated by small tweaks of our stroke to keep all our body parts in alignment and in its natural way.
One of the major culprits I have noticed in freestyle is linked with the position and the direction of the hands entering the water. Very often, the swimmer is entering with the thumbs down which automatically puts pressure on your shoulders. In a natural way, if you are standing up with your arms at your side, your palms are facing your body. If you lift your arms over your head, you will feel less stress on your shoulders with your thumbs slightly facing back and the most with your thumbs facing the front. Putting you on a horizontal position on top of the water, it means if you want to avoid stress on your shoulders with every stroke you make, enter your hand with your major fingers, pinky slightly turned down and thumb slightly up.
Once in the water, most of us are gliding our arms towards the middle, which may bring our body out of alignment (we are not in the twist dance class) and put stress on our shoulder joints. Instead, make sure you are gliding towards the front and or slightly towards the outside, especially if you do not have flexible shoulders. It will bring you in a better position to pull more efficiently and without tearing your shoulders apart. Just those little tweaks may make the difference between healthy shoulders and painful shoulders.
Thanks to the pandemic, some of us now have the luxury to swim one per lane and have a black line on the bottom of the pool to practice my favorite drill to check alignment and position. Swim with your body staying on the black line. Except for your arms, which should remain on each side of the line and never get over it, your whole body including your legs and feet should stay tightly on top of the line. Force yourself to keep your eyes on the black line and your head in alignment with your body in the most natural way possible, not lifting or dropping your head and simply turning your head to breathe. Think how you are holding your head and body in a neutral position when walking and simply keep that natural position horizontally on top of the water. It will relieve any tension you might feel in your neck. This is an excellent warm-up exercise which should help you tune in with the movements of your body and help you feel where you might need a little tweak of your stroke.
Do not reinvent the wheel. Keep your body, arms, and legs in a natural, pain-free position while swimming, and use your core and glutes to stay in alignment. Think how you would put your arms and hands if you were in a resting position on land. Tweak your stroke accordingly and keep swimming pain-free and happy for a very long time.