Walking is a skill that many of us take for granted – let’s face it, when was the last time you actually thought about the way you walk? Yet it is still a skill, and when your ability to walk is suddenly impeded, or lost altogether, you realise just how important it is to your life. Even with disease or injury, many of us find a way to maintain our ability to walk, however any deviation from ‘normal’ gait (the medical term for walking) can often result in the development or compounding of other problems: pain, muscle imbalance, and arthritis being some of the more common, not to mention the difficulty in attending to day-to-day activities.
What is ‘Normal’ Gait and Why is it Important?
I often explain gait as a “controlled fall”. In order to walk, we shift our center of mass (CoM – see Part 1 for an understanding of the importance of CoM) forwards so that our body starts to move forwards. If we allowed this shift in CoM to continue unchecked, we would fall flat on our face. To avoid this, we use a complex pattern of movements to support ourselves on one leg while we place the other one in front of us to arrest our fall. If we keep our CoM moving forward, we have to repeat the pattern again: the leg in front now becomes the supporting leg, and the leg that was supporting us must now swing forward to save us. Repeat over and over again and you are walking.
The way our limbs and body produce this – not just the movements themselves, but the way they are coordinated – is referred to biomechanically as a ‘gait pattern’. A ‘normal’ gait pattern is a complex, ideal version of these coordinated movements that result in a stable and efficient means of locomotion which has minimal impact on our musculoskeletal system. It is defined by a number of different factors, including joint angles, distribution of mass (ie: the location of CoM), forces applied to the body, and synergy of movements. For a more in-depth explanation of normal gait, check out this article on Physiopedia.
Anything that doesn’t comply to a ‘normal’ gait pattern is considered to be an ‘abnormal’ gait pattern. This is not to say that it is wrong as such, merely that it does not conform to the ideal that is normal gait. Physical Therapists strive to teach people to walk with a normal gait pattern, or as close to a normal pattern as is achievable. For some people this might not be possible, for example, due to anatomical differences, muscle weakness, imbalances, or tightness, neurological changes or deficits, pain and/or injury, disease, aging, or some combination of these factors. However, while the ‘perfect’ gait pattern might not always be achievable, many people who experience problems with walking can be assisted through Physical Therapy to improve their gait pattern, and in doing so their overall functional capacity.
How Can Tai Chi Help?
Students of Tai Chi spend a lot of time learning to walk correctly. One main example of this is the technique known as mao xing, or ‘cat walking’. In mao xing, the Tai Chi practitioner shifts weight into one leg while stepping forward with the other. The stepping leg has no weight in it right up to the point the heel makes contact with the ground. The practitioner completes the step by gradually transferring weight from the supporting leg to the stepping leg, involving a shift from side-to-side and back-to-front. As the stepping leg is loaded it becomes the supporting leg, eventually freeing up the other leg to take another step forward.
This sounds very similar to normal gait, however a key difference is the location of the person’s CoM. As already described, normal gait requires the CoM to be displaced forwards outside the person’s base of support BoS), providing momentum. In mao xing, however, the CoM is maintained within the BoS while weight is shifted from one limb into the other, effectively eliminating the “falling” part of walking. To do this successfully, the Tai Chi student must develop a deeper understanding and awareness of how their body moves, in terms of coordination, weight shift, loading and unloading of the limbs, and placement of the feet. As a Physical Therapist, if I could have all my patients mao xing I wouldn’t have to worry about any of them having falls!
Applying Tai Chi to Physical Therapy: Recovery from Joint Replacement Surgery
Recently I’ve been applying the principles of mao xing in retraining normal gait patterns in patients who’ve undergone total hip or knee replacements. In the first weeks after surgery, many joint replacement patients demonstrate a very “stiff-legged” gait pattern: they tend to hold the operated leg very stiff when attempting to mobilise, and limit the amount of time they bear weight through the limb. In some cases the patient will circumduct or swing their leg around rather than bend their hip and knee in order to take a step forwards. Some patients may also have been walking like this for sometime prior to their surgery due to the nature of the condition that required joint replacement.
It can be quite challenging to retrain patients to walk with a normal gait pattern again, and often requires very precise practice. This has been particularly true in patients who have had bilateral joint replacements, who don’t have a ‘good’ leg to support themselves on and so are very guarded with attempting to walk.Though I haven’t been trying to teach my patients mao xing as such (though I often think I would like to), I’ve found that incorporating a number of the principles of mao xing – stepping onto the heel, rolling through the foot to come up onto the toes and push-off – as well as instructing the patient in a similar manner to how I would teach the technique to a Tai Chi student, provides a much more correct and consistent result than other methods I’ve tried. I’ve also found in practice that focusing on the principles related to the foot (heel strike, weight shift, stance, toe off) produce a subsequent improvement in the pattern of movement at the knee and hip – that is, an increase in the amount of flexion at the hip and knee during swing phase – and tolerance to weight-bearing during stance phase. When I apply these principles to gait training, I seldom have to draw attention to or correct movements at the hip, knee, or lumbo-pelvic area as these seem to correct themselves when the patient is applying the principles to their feet.
Lastly, and in some ways the most exciting part, is that I’ve found that patients are more likely to practice this “creeping” (as several patients have referred to it) way of walking as part of their home exercise program than they are other techniques or exercises designed to improve their gait. The exact reason why is unclear, however I would suggest it is because it is easier for the patient to conceptualise, understand, and apply, than other techniques that are more detailed and require a higher level of cognitive processing. In practice this apparent increase in compliance and attendance to exercises between therapy sessions does appear to translate – in general – into a more timely improvement in gait and physical function.
Again, this is at best observational evidence of a specific application of Tai Chi principles to physical therapy. However, it does support the increasing body of evidence-based research advocating Tai Chi as a means of improving balance and mobility, and in my opinion, is worth further investigation as an adjunct to physical therapy.