As a keen amateur swimmer and beginner triathlete, the biomechanics of swimming are of curious interest to me working in the profession of osteopathy, particularly the stroke of freestyle/front crawl.
To break the stroke down, but not to over complicate things for the benefit of those with little or no biomechanical/anatomical knowledge, the conventional freestyle stroke involves the athlete being in a prone position with the head tilted back into extension. Forward momentum is generated predominantly from the muscles of the chest and shoulders with input from other muscles such as the latissimus dorsi (back) and the gluteus maximus (bum). The shoulders generate "pull" from an out in front position, that if you were standing out of the water, would be the equivalent of reaching way up over your head and trying to pull yourself up an incline. The result of this position, is the muscles of the shoulder being placed into a repeatedly vulnerable position, where they are brought into close contact with the bony structures of the shoulder girdle. Knowing this, it may not surprise you that, according to various research papers, between 40 and 91% of swimmers over the duration of their careers will suffer a swimming-related shoulder injury. This is a rather alarming rate of injury, I'm sure you'll agree, especially for a sport which is considered to be low-risk for injuries.
The conventional stroke also places the neck and low back under strain due to the prone positioning of the body. The neck is held in extension (tipped back) placing stress on the bony and muscular structures at the back of the neck, whilst the low back is often arched with shear forces being placed on the lower spine when the legs are kicked. It is the lower level amateur and "weekend warrior" swimmers who are more susceptible to injuries affecting these areas, owing to generally lower levels of fitness and strength, than club or elite swimmers.
The Ocean Walker Technique is nothing less than a revolution in swimming stroke technique. Devised by Adam Walker out of necessity after he suffered a serious, career threatening shoulder injury. It completely changes the biomechanics of freestyle swimming. Instead of power being led and generated by the chest and shoulders, it is instead generated by the muscles of the "core" in a rotational movement of the legs, hips and lower torso. It takes inspiration from other sports such as golf and tennis, which use the same "core muscles" to generate power and timing. The shoulders assist forward propulsion from a biomechanically much safer position, operating below 90 degrees of movement from the side of the body, thus reducing compaction of the shoulder structures...