Numerous studies have shown that exercise programmes are the most effective treatment for other lower limb tendon problems, particularly the Achilles and patella. These programmes typically last a minimum of 12 weeks and are often prescribed by physiotherapists as first-line treatment. However, there is currently limited evidence to support exercise for gluteal tendinopathy. The study plans to directly compare two different types of exercise programmes for those with GTPS for a period of 12 weeks. One group will receive an isometric exercise programme (where the muscle length does not change) and a second group an isotonic exercise programme (where the muscle length does change).