The Achilles tendon is the thick band of tissue at the back of the heel that connects the calf muscle to the heel. Achilles tendonitis occurs if that tendon becomes irritated and tightened due to chronic stress, usually from a dramatic increase in training mileage, and makes up 11% of running injuries according to a Runner’s World article. It’s best to address this type of injury right away because if the tendon becomes chronically irritated and
