Total Knee Replacement
I was doing some noodling around on the internet and slid on over to PubMed.com
I love being able to do a TON of quick research using keywords and only getting back abstracts of published articles in medical journals. I found some support for things I've known intuitively or through anecodotal stories or by reading popular media, but didn't necessarily have direct reference to research to understand the mechanisms.
I'm talking about the link between healing and exercise.
There are a couple of factors that can negatively impact healing. Stress is a big one. Poor circulation is another. Nutrition is definitely in there and I have talked about that in this blog before. Immune system functioning is important as well.
It turns out exercise helps in all these areas except nutrition (well...after working out, I always eat a little something, and make a point of only taking in protein and complex carbs, so I guess you can cover nutrition off a little bit as well).
As you might guess, after any major surgery, such as total knee replacement one of the biggest problems for the patient is reduced function and mobility. Reduced function and mobility inevitably leads to increased stress for the patient.
Stress has a negative impact on the healing process. In Neuroimmunomodulation, Vol 13, 2006 Glaser and Christian write that “…stress can significantly slow wound healing: stressors … impair healing in humans and animals. For example, in humans…the relatively brief stress of academic examinations impedes healing.” They go on further to state “Recent evidence suggests that interventions designed to reduce stress and its concomitants (e.g., exercise, social support) can prevent stress-induced impairments in healing.”
In 2005 report was published in the Journals of Gerontology describing a study on exercise and healing among older adults. There were some surprising results. The study divided 28 adults, with an average age of 61, who had not exercised in the previous 6 months into two groups. Half the group exercised for 75 minutes, three times a week. The other half did their normal routine. After 4 weeks, all the adults got small puncture wounds on their upper arms. They were also given stress tests, once at the beginning and once at the end of the study. Their cortisol levels were measured both before and after each stress test.
Neither group had an increase in cortisol levels after the stress test. Normally exercise increases cortisol levels. With age, the body loses its ability to produce cortisol. This is important because cortisol helps the efficiency of the immune system. Older adults typically take longer to heal than younger people.
The conclusion of the study was that the exercisers healed 25% faster, taking 29 days instead of the 39 days for the non-exercisers. Now the researchers expected this. Afterall exercise increases circulation, and that should improve the flow of nutrients to the wound site and the flow of wastes away from it. The surprise came when they administered the stress tests at the end of the study. The exercisers showed increased cortisol levels typical of younger adults. They reasoned that the increase in cortisol levels may have helped promote improved healing.
Exercise also plays another important role in adittion to boosting healing rates. Patients that undergo total knee or hip replacements are dependent on walkers and canes for mobility during their recovery. Increased exercise load on the upper body can lead to soreness and pain.
In 2007, the May issue of Journal of Strength and Conditioning Research reported on the results of a case study involving two TKA patients. One follwoed a 4 weeks program of pre-habilitation exercises. (Pre-habilitation is physical therapy delivered before any surgical intervention). There were significant differences in both function and self-reported pain perception in the exercising case than in the non-exercising case.
An earlier study, reported in the February 2002 issue of Applied Nursing Research, found that when they looked at the effect of preoperative exercise, anesthesia, or analgesia on the ability to walk after surgery, anesthesia, or analgesia had no effect. But subjects who exercised before surgery were able to walk significantly greater distances afterwards.
So boil it all down and what do we have? Easy. Exercise helps promote circulation for wound healing. It regulates cortisol levels, especially in older adults. It strengthens the body, particularly important if you are going to be using assistive devices like walkers or canes that you are not used to. And it reduces stress, by helping make you more fit, therefore more able to cope on your own, and as a simple rphysical release for stress.