Your joints may tend to hyperextend, in other words extend beyond a safe range. You are basically resting on your ligaments rather than recruiting your muscles. This is something you see in people who stretch a lot, like yoga practitioners and teachers, gymnasts, etc. and some people are born with hypermobile joints. You need length but you also need strength in your muscles. You need both mobility and stability in your joints. Once you know how to align yourself, you can move safely within a safe range of movement, stabilise your joints and strengthen your muscles.
In my restorative exercise specialist training, I've learned to spot this in myself and in others as well as to self-correct and help others self-correct.
Feel free to contact me for more info or to book an appointment for massage and/or restorative exercise.