Achilles tendonitis can affect people of all ages and genders. Nonetheless, some factors make you more susceptible to Achilles tendonitis. These factors include age, sex, weight, fitness level and side effects of other medical treatments. Achilles tendonitis is most prevalent among people in their 30s – 40s. Males are up to 5 times more susceptible to Achilles tendonitis than females. People who participate in recreational or professional sports are at higher risk due to rigorous use of the Achilles tendon in sporting activities. People who have previously received some form of steroid injection in the foot, like the ankle joint, may experience weakened Achilles tendons. Obesity also puts excess weight on the Achilles tendons.