Being hyper mobile means that you can have an excellent range of motion but sometimes have excessive mobility which, when over-executed, can cause pain and injury. Injury can be due to not knowing what intensity of weight to stop at or over stretching. Sometimes yoga can be quite dangerous for people with hyper mobility not because of the system of yoga but because the pupil or the student didn’t stick to the range or technique and just stretched/tried as hard as possible without consciously thinking or listening to healthy and unhealthy signs from the body.
Weight training is fantastic for people with hyper mobility when executed properly because it works against gravity and, with correct weight and load, will give density and develop the thickness of the joints, ligaments and skeletal system. The thing that is most important is the technique, the correct weight with careful progression, and the correct range of motion depending on the movement. The ideal is to get a full range of motion of the exercise and of the muscles while not hyperextending in order to build the muscles around and supporting the joints, ligaments and bones. So, as I always promote, the goal is to get strong with an awesome range of motion. There’s no point in being weak with excellent range or being strong but limited in movement. The key is to gain balance in order to achieve that healthy ideal.