Based on the title of this article, you might be wondering why it appears in a neurology column. The answer is straightforward. Basic sciences are typically taught in a compartmentalized fashion, such that students and doctors cannot appreciate the interrelationships, and more importantly, the interdependencies among anatomy, neurology, biochemistry, nutrition, and exercise physiology.
The tragedy in medicine and chiropractic is that we have arbitrarily dissociated ourselves from inseparable physiological relationships. Subsequently, we are left without a solid foundation on which to base our treatment approaches. For this reason, we feel it is important to include such articles as this one by Dr. Goodman, which will help DCs to better understand key physiological relationships between aerobic exercise, spinal function and neurology. I am sure that you will find Dr. Goodman's article to be insightful and practice enhancing.
The human animal is designed for movement. That is why, of course, patients seek your care -- they can't move effectively, or without discomfort or pain. Indeed, if movement was not required in life, chiropractors and most health care providers would be out of business. Then again, homosapiens would not have become so "successful" a species.
Movement in our world usually means for most people the ability to carry on with their daily tasks: no more, and no less. This might entail manual labor, sitting in front of a computer, or making beds. We usually associate our physical capacity in terms of whether we can or cannot accomplish a task of daily living. This is where the notion of reserve enters. Many North Americans have no reserve, just (barely) the capacity for the current task at hand. Aerobic exercise training gives people that reserve, and at the same time confirs important cardiovascular and biochemical adaptation which synergistically complement the chiropractic treatment model.
In the first article, I hope to convince you that the understanding of the physiological adaptations which accompany a properly planned and executed endurance exercise program for your patients will help the treatment and rehabilitation of the patient.
In a second article to follow in the next neurology column, I will summarize some exercise prescriptive techniques. The concepts covered in both articles are expanded on in far greater detail in the upcoming MPI seminars.
Skeletal Muscles
Rhythmic, dynamic (isotonic) exercise is natural to occupational and leisure movement. Even in the untrained state, the muscles involved in human locomotion are unique. If viewed under magnification with appropriate biochemical staining, one notices that they contain a blend of fast and slow-twitch fibers, with the locomotor (soleus) and postural (erector spinae, multifidus) muscles composed of mainly slow-twitch (red) fibers. The red is due to the high myoglobin content. These muscle fibers also have a dense mitochondrial matrix, containing the biochemical machinery for oxidative phosphorylation (oxidation of oxygen). In other words, they have a large capacity for sustained but low-tension contraction. They are very resistant to fatigue, and use much oxygen in the production in ATP.
The functionality-specific muscle group concept is highlighted by the differences one notices in birds. That nice white turkey breast is white because it has little myoglobin. The endurance aspect of these prime movers has over the years been removed by breeding such that the turkey cannot fly. In contrast, the migratory bird species have breast muscles which are highly oxidative. It is red, and under the microscope displays a highly developed mitochondrial density. It has evolved for endurance flight. The hummingbird also displays extraordinary muscle biochemistry, with highly developed oxidative machinery in its muscles.
As far as the human animal goes, we can biochemically "model" our skeletal muscles in opposite directions of the continuum by either inactivity (atrophy in the case of sickness, space flight, sedentary living), or by habitual vigorous activity (hypertrophy in the case of resistance training; oxidative enhancement in the case of endurance training). I prefer to think that the endurance-based adaptations which occur in human skeletal muscle after a period of aerobic condition are the most important and relevant to health, the subluxation complex, and chiropractic in general.
Regularly performed endurance exercise impacts positively and profoundly upon your patients' well-being (emotional, spinal, musculoskeletal and cardiovascular).
- Cardiovascular: The Center for Disease Control (CDC) and American Heart Foundation now recognize the cardioprotective benefits of regularly performed aerobic exercise. These benefits include a slower resting pulse and relatively slower exercising pulse (favoring an increased diastolic filling time, the period when coronary arteries fill; reduced myocardial oxygen demand; favorable blood lipid profile (especially a raised HDL-cholesterol); reduced platelet clumping; increased red-cell mass; increased plasma volume; increased coronary collateralization (especially beneficial with undiagnosed or coexisting coronary disease).
- Metabolic: Insulin response is more stabilized; catecholamine output is reduced at rest and during exercise; b-endorphin release is increased (giving that natural "high" and sense of well-being); basal metabolic rate is increased at rest many hours after exercise.
- Body Composition: Lean body mass is increased while body fat is reduced due to the above points (especially important for individuals who favor trunk-located body fat deposition patterns; a pattern linked to higher incidence of coronary disease and diabetes); posture and center of gravity is altered favorably, improving spinal health; cardiovascular function is improved during exercise (especially in weightbearing activities); metabolic heat removal functions are enhanced (surface area is increased).
- Skeletal Muscles: Oxidative capacity is increased in the trained muscles increasing peak oxygen consumption by 10-30 percent; capacity for prolonged exercise/work increases 10-400% (based upon training volume and intensity of activity trained for); capillarization of trained muscles increases four-fold (number of capillaries per muscle fiber increase from 2-3 to 4-8.
- Axial Skeleton: Bones increase in density; synovial fluid secretion/production increases; osteoporosis risk decreases, especially in postmenopausal women.
- Immune Function: General immune function is enhanced (excepting after an unaccustomed and intense bout, where it temporarily is depressed).
As discussed frequently by my colleagues, a major component of the subluxation complex is nociceptive irritation. The chiropractic manipulation stimulates spinal cord interneurons, thus inhibiting pain, relaxing muscles, and reducing vascular constriction. Is it not unreasonable to believe that these favorable clinical outcomes will work in concert with an exercise program which illicits the outlined alterations in biochemical and metabolic function. Exercise promotes muscle vascular dilation. It encourages muscular relaxation. It heals.
Is it also not unreasonable then to presume that encouraging your patients to adopt a lifestyle which incorporates endurance fitness will enhance your efforts? These adaptations can be prescribed to patients of all types and ages, with many clinical presentations. Exercise prescription becomes part of your preventive and rehabilitative arsenal.
In next month's article, I will elaborate upon these methods and techniques, laying out several fundamentals of exercise prescription. My parting thought however pertains to setting the example yourself. Invariably, your patients will adopt your suggestions and exercise prescriptions when they see you engaging in regular exercise, and enjoying the benefits of your renewed energy, enthusiasm, and zeal for life.
Len Goodman, PhD
Toronto, Canada