The adductor muscles run down the inside of the thigh. The tendon can become injured where it arises from the pelvis due to over use. Microscopic tears within the tendon lead to accumulated damage resulting in a tendonitis. Repetitive strain is more common in sports involving lots of side to side motion such as football.
Pain is felt high on the inside of the thigh or groin. Initially is may be only after exercise, or on the following morning, but as the condition gets worse the pain my become more intrusive. Initially the pain will settle with warm up and will not disturb play, but with time, if untreated this may interfere with your performance.
If you think you have this injury it is well worth getting it checked out by Mr Willis-Owen. In the mean time you should avoid any aggravating activities with may prolong the problem. Apply ice to the area after sport, and start gentle stretching.
Treatment involves first confirming the diagnosis which may involve ultrasound or MRI scans, then establishing the underlying cause. Options may include activity modification, physiotherapy, and anti inflammatories. Rarely an injection or surgical treatment is needed.