A lot of people don't realize that this skill set is part of the PT scope of practice (provided you attended a school or had some other form of training in the skill). There are differences between professions in how and why "cracking" joints is performed along with different terminology, but the main point to get out there is share how the techniques can enhance a rehab session in very powerful ways beyond just the "crack."
In physical therapy, the term we use is manipulation. With physical therapy sharing a lineage with osteopathy, manipulation of the spine or any other joint system is grounded in one of the core tenets of osteopathic medicine, which is the body has the innate ability to heal itself. Our role as practitioners is for the body to reach a homeostasis that enables this self healing ability. We're not putting joints "back in line" or fixing things "out of place." We're simply using a technique with the body that can make some change to create a more optimal environment for healing.
If a physio manipulates your spine, for instance, you clearly feel a change to your body in the immediate aftermath. That's simply signaling that some change has occurred in the short term which creates conditions for the body to more effectively deal with any problems internally.
So once we perform the manipulation, that's actually when we're getting started. We're squandering ripe opportunities for improvement if we stop there. Yes, we can still benefit if that's all the session entails, but the "magic" in the manipulation is how it allows us to move better to do the physical work and even psychological work during that SAME SESSION that will have the greatest long term change for the body.
I always say there are some things you just can't exercise your way out of, or at the very least that exercise alone without other techniques will make for a longer road toward healing. Adding manipulative therapy into a session literally allows us to supercharge EVERYTHING that we do. What it also does is make our results more durable, meaning because we achieve such a potent effect with the combo of manipulation (and other manual techniques) plus exercise, you don't need to come in several times per week to see results. It's like taking your car to the mechanic and having them fix the problem, versus having to come in multiple times per week to keep topping off fluids leaking from the engine.
It also avoids the common scenario where you might get some wonderful treatment on the table and feel amazing, but then get in your car and drive around for a while or return to work at a desk for the body to revert closer to where it was before treatment. Then you go exercise in a separate session and you've lost some of the immediate benefit of the therapeutic technique.
Bottom line: physios are trained to perform manipulative techniques (joint "cracking" in crude lexicon) and doing so allows the amazing results achieved within comprehensive treatment session to have the longest lasting effect.
Allan Phillips, PT, DPT is owner of Ventana Physiotherapy