One of the most common complaints during a Pilates class is the presence of hip clicking, especially during exercises that require any unsupported movement from the pelvis. From your Side Lying Glute series to even some basic Supine Abdominal exercises, there will usually be someone who will experience some form of discomfort in their hip socket. As an instructor, there are things that you can do which can help decrease the clicking and often fix the problem altogether.
There are several types of injuries that your hip joint can sustain, but all lead to poor gluteal strength, an overactive Psoas and a weak, underactive Iliacus muscle. This creates an unstable muscular balance within the hip, so during movement, it is difficult for the femur to stay within the confines of the hip joint. Excessive movement of the femur causes unwanted interaction with adjacent cartilage and muscles, resulting in an uncomfortable 'click' or 'pop'. Pain may or may not accompany the click.
To help your clients and class participants from experiencing this clicking sensation, you need to address the underlying problem the imbalance of the muscular support system for the hip joint.
Firstly, is the overactive hip flexors. You can decrease the influence of the hip flexors by positioning your legs and body in a way that it will be difficult for them to activate. For example, during Clam Kickouts, emphasise the hip extension component of the exercise so that your psoas and quads are in a stretched position. During abdominal exercises, get your client to use a circle in between their knees, or when they go into Hundreds keep them with their legs and feet turned out. This decreases the chance of them using their hip flexors as other muscles (ie their abdominals and inner thighs) are in better position to work.
Secondly is the weak Iliacus muscle. The function of the Iliacus is to stop forward translation of the femur, so it is obvious that when this muscle is weak that the stability of the hip joint is compromised. You can strengthen the Iliacus by just cueing people to turn these muscles on while they do their normal Pilates exercises. A nice way to explain to someone on how to switch your Iliacus on is to try and draw your femur (leg bone) towards your hip socket. People will instantly feel as if they are more stable, and commonly say that they can also feel their Tzone work better as their legs are not doing the work of your abs.
Lastly, but just as important, is strengthening the gluteal muscles. This is mentioned last only because if a client cannot control the overactivity of their hip flexors and also can't turn their Iliacus on, their glutes will never work. So after you have addressed the issues in the anterior component of their hip joint can you start working on the posterior aspect. Gluteal strength can be achieved via any exercise that targets these muscles, but just be aware that a person who experiences hip clicking will have a body that will try everything it its power not to use their glute muscles.
Hip clicking is a frustrating problem for clients, but one that can be helped with a little persistence. The great thing about Pilates is that it addresses the underlying problems of hip instability, but you just have to make sure they are in the right position and to concentrate on the right things for them to get a benefit. You should not need to change a program completely to accommodate for someone with this problem, rather just be more careful with what you say or how they perform their exercise.