The most important ingredient in the recipe for progress in triathlon is consistency, and the key to consistency (besides discipline) is staying healthy.
Every triathlete should make health maintenance the top priority of his or her training. If you do this, fitness will more or less take care of itself.
Here are my three golden rules for training injury-free, all learned the hard way.
Stay in Balance
Muscle imbalances are a causal factor in relation to a majority of overuse injuries. No muscle ever works alone. In order to function optimally, each muscle needs to cooperate with other muscles, and optimal cooperation, in turn, requires that cooperating muscles be balanced in terms of their length, elasticity, and strength.
Most triathletes come to the sport with pre-existing imbalances that are due to individual physiology, adaptation to lifestyle (especially sitting), and past injuries.
Training itself tends to exacerbate some of these imbalances and to create new ones, and eventually these lead to injury.
For example, running often creates tight, strong hamstrings and tight iliotibial bands while leaving the vastus medialis (the muscle on the inner side of the front of the thigh) relatively loose and weak. As a result, the kneecap can begin to track incorrectly during running, leading to cartilage damage.
You can reduce and prevent imbalances by strengthening muscles that are relatively weak and stretching muscles that are relatively tight. In order to do this in a targeted way, you need to know your imbalances.
Muscles that tend to become too tight in triathletes are those of the calf, the hamstrings, the hip flexors, the piriformis, the internal shoulder rotators, the neck extensors, and the chest muscles.
Two major tendons, the iliotibial band and the Achilles tendon, also tend to become tight.
The muscles that are typically underdeveloped in triathletes are the medial and frontal shin muscles, the hip abductors, the gluteal muscles, the abdominals, the scapular stabilizers and rotator cuff muscles—all of which every triathlete should proactively strengthen with resistance exercise.
But each body is unique, so I recommend that you seek out a good sports massage therapist or physical therapist who can help you identify your precise combination of imbalances and suggest exercises to correct them.
More than half of the overuse injuries I have suffered have been related to the repetitive impact of running. I believe this ratio holds for most triathletes.
By making consistent efforts to minimize the amount of running impact your lower extremities are subjected to, you can greatly reduce the amount of injury downtime you endure.