Swim all strokes, not just freestyle. Triathletes, I have found, tend to have the mindset that because they only race freestyle, they should only train freestyle. Unfortunately, they are not considering the big picture. If you overwork muscles in one direction and don't equally strengthen the opposing muscles then it will result in muscle imbalances. Why is that a problem, you might ask? Well for starters it can make your joints more prone to injury and thereby damaging the cartilage. Movement occurs when one muscle contracts while the opposing muscle lengthens. If one muscle is stronger or tighter it can pull joints out of alignment as it overpowers the opposite muscle. Muscle imbalances can therefore create joint dysfunction and can lead to postural changes and injury. This is what can happen to the shoulder joints of those swimmers who only swim freestyle. The range of motion, flexibility and reaction time of the muscles can also become compromised with the overall performance of an athlete being adversely affected. Swimming all four strokes gives a greater all body workout. Swimming provides low impact exercise on the joints unlike running, so for cross-training purposes swimming is the way to go. Backstroke is the great companion to freestyle as it turns the shoulders in the opposite direction, helping to minimise the chance of muscle imbalances. Breaststroke kick helps to work the inner thighs and buttocks and butterfly helps to build lower back and core strength.