When we exercise, multiple organ systems in the body perform autocrine, paracrine and endocrine functions to dramatically alter cellular and systemic chemical milieu effecting all other cells and tissues – producing endogenous medicine so that exercise is truly a medicine.
How it all works
In fact, the skeletal muscle system is recognised as the largest endocrine organ in the body, producing a vast array of hormones and cytokines critical for maintaining health.
Adipose tissue is also secretory and much of the chronic disease epidemic is driven by the imbalance of dominance between muscle and fat mass and regulatory activity.
As a result of exercise, the chemicals produced ameliorate the imbalances that cause diseases, reversing decline in health and in some cases with chronic exercise actually curing the disease.
Unfortunately, Australians in the vast majority have a high volume of fat tissue and low muscle tissue due to sedentary lifestyle and inappropriate nutrition. A key priority for improving health is to increase muscle mass and stimulate it to dispense beneficial medicine regularly. (The analogy is build a pharmacy and visit it regularly but ensure the appropriate medicine is provided. A large fat mass provides detrimental chemicals into the system with sedentary behaviour stimulating release.
Getting the balance right
Interestingly, there is quality research indicating that aerobic and neuromuscular fitness, including higher muscle mass, is more protective against poor health than striving for normal body fat levels. High body fat remains a major risk factor. However, a greater health benefit will be derived by focusing on exercise rather than fat loss.
Of critical importance, dietary restriction or bariatric surgery, while generally effective for fat loss, also produces decline in muscle and bone that can result in worse health problems than the obesity may cause. Any fat loss program MUST include an exercise prescription to maintain muscle and bone health and increase physical fitness.
Exercise and cancer
Exercise is increasingly being prescribed across the cancer continuum as part of management: from diagnosis and leading up to surgery, chemotherapy or radiation; as rehabilitation post-treatment, to enhance longer term survival and reduce risk of recurrence; and to maintain function and quality of life in patients with incurable disease.
The effect of exercise on survival in breast cancer patients and prostate cancer patients has been demonstrated to be similar in benefit to some chemotherapy agents.
Research has demonstrated that higher muscle mass is associated with less chemotherapy toxicities and increased survival for patients with both metastatic and non-metastatic cancers. For these reasons alone, exercise should be prescribed for cancer patients to maintain or increase their muscle mass to help fight the disease.
Preclinical trials have demonstrated specific exercise enhances the effectiveness of chemotherapy and radiation therapy. Recommended practice is for patients to complete an exercise bout immediately prior to their therapy session to increase blood flow through the tumour, delivering more chemotherapy or enhancing radiation effectiveness.
Where is exercise medicine heading?
Increasingly we are coming to understand through research and clinical practice that the mode and dosage of exercise varies considerably, as do indications and contraindications.
Take walking as an example. Too often walking is recommended to patients in a non-targeted way possibly because it is free and easy to access. But walking does not benefit the patient suffering from osteoporosis or sarcopenia. For a patient with cachexia secondary to cancer, walking is contraindicated as it will increase energy deficit and drive further weight loss and functional decline.
Exercise medicine is moving towards a tailored prescription where the health issues are given priority according to morbidity and risk of death. There is no point putting new seat covers on when the engine is about to explode!
We must discard the belief that exercise must be fun. Statin therapy is not fun. Having your prostate blasted with radiation for six weeks is not fun. But informed patients choose to receive these treatments. Exercise medicine must be promoted in the same vein, a necessary part of medical management.
A major barrier to patient access to quality exercise medicine is that Medicare only funds up to five consultations with an accredited exercise physiologist (AEP) per year. Compared to pharmaceutical therapies, exercise medicine is relatively inexpensive, has no side effects and benefits a range of health aspects beyond the primary disease being treated.
This has been demonstrated very effectively through Medicare support of exercise medicine for patients with Type 2 diabetes. However, to improve patients with other diseases and reduce health costs overall, the Medicare rebate for group exercise must include all chronic conditions.
The AEP seems well placed for exercise assessment and prescription – a minimum four years university trained, accredited through Exercise and Sports Science Australia and can be registered providers through Medicare (see www.essa.org.au/find-aep/)
References available on request.
- Hart N.H., D.A. Galvão and U. Newton. Role of exercise in advanced prostate cancer. Current Opinion in Supportive Palliative Care. 11(3): 247-257. 2017. IF 2.070.
- Newton, R.U. and D.A. Galvão. Accumulating Evidence for Physical Activity and Prostate Cancer Survival: Time for a Definitive Trial of Exercise Medicine? European Urology, 70(4): 586-587. 2016. IF 13.938.
Author competing interests: no relevant disclosures.
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