I had a nagging shoulder problem that got so bad I could barely lift my arms past horizontal. I've been working out for years, but one very, very rough weekend sports outing trashed both shoulders to where I couldn't work out at all. This book with it's simple exercises totally cured my problem. Now I just incorporate them into the end of my shoulder workout and VOILA !!! Pain and injury free for 4 years now and my workouts are better than ever. The technical explanation is superb. The best money I ever spent. Better than any help I ever got from physical trainers and doctors for the same problem.