The Beneficial Effects
Of Exercise And Yoga On Diabetes: A Survey Of Medical Research
by Marshall Govindan, M.A. and
Dr. Emilia Ripoll-Bunn, M.D
Diabetes is a devastating medical condition affecting people of
all ages, genders, and nationalities. Diabetics have an inability
to bring glucose in from the blood to the cells. This abnormality
is due to either a decrease in the production of insulin by the
pancreas or an insensitivity of the cells to respond to the insulin
present. In either case, the end result is that there is a low
level of glucose in the cells and an excess of glucose in the
blood stream. It is believed that high glucose levels in the blood
lead to vascular damage, resulting in decreased blood flow to
all areas of the body. It is this process of diminished blood
flow which is responsible for conditions such as diabetic retinopathy
(which can cause blindness), neuropathy, kidney failure, urinary
difficulties and loss of limbs.
There are two forms of diabetes.
Type 1, known as insulin dependent or juvenile diabetes, where
almost no insulin is produced, manifests especially in young persons.
However, it can also affect the adult under 40 years of age, and
occasionally older persons. Very widespread, type 2 diabetes (non-insulin
dependent) there is only reduced production, normally attributed
to some degenerative process. It manifests especially in persons
older forty who are overweight.
MODERN MEDICAL RESEARCH IN THE WEST
AND INDIA
Clinical research in the west
has focused exclusively on diabetes as a physical disorder, and
hence the treatments that have been researched have involved stimulating
the pancreas through drugs, or by controlling the glucose levels
by dietary restrictions, artificial insulin, and more recently,
by physical exercise. The results of the research on the beneficial
effects of exercise will be first surveyed.
Clinical research in India,
by contrast, has recognized that diabetes is a psychosomatic disorder,
in which the causative factors are sedentary habits, physical,
emotional and mental stress and strain. It has studied the beneficial
effects of the practice of yoga, which is much more than a physical
exercise. Yoga addresses the whole person, considering not only
their physical needs, but emotional, mental, intellectual and
spiritual needs as well, through gentle movements, relaxation,
breathing, lifestyle attitudes and meditation. The results of
this research will be surveyed in the second part of this paper.
Yoga addresses the whole person,
considering not only their physical needs, but emotional, mental,
intellectual and spiritual needs as well, through gentle movements,
relaxation, breathing, lifestyle attitudes and meditation. The
results of this research will be surveyed in the second part of
this paper.
Part I. WESTERN MEDICAL RESEARCH ON
THE EFFECT OF PHYSICAL EXERCISE ON DIABETES
Insulin-dependent (Type 1)
Type 1 diabetes occurs when
the pancreas is incapable of secreting sufficient insulin to eliminate
the excess of glucose in the blood. Insulin helps to control glycimia,
the rate of glucose in the blood, and transforms the excess of
glucose (provided by one's food) into fat. Type 1 is more difficult
to control than Type 2.
Clinical observations have demonstrated
that vigorous physical activity helps diabetic children to better
control their level of glucose. (1) Shepard (2) emphasized that
in certain studies where the diabetic children were subject to
training program, some saw their need for insulin significantly
reduced, and others were able to finish diabetic treatment. It
is known also that extreme sedentary living, for example, when
one is confined to bed, bring a deterioration in the control of
glucose. Because of these observations, it was thought that exercise
could constitute an important element in a program to control
Type 1 diabetes. However, the several serious studies done in
the West have not shown conclusive results. When the quantity
of insulin produced is too low, it seems that exercise does not
provoke in the muscles, sufficient utilisation of glucose to effectively
lower glycemia. It is thought that the weak utilisation of glucose
by the muscles could be due to, among other things, the presence
of fatty acids in large volume, as a energy sublayer.
If the control of Type 1 diabetes
seemed to be little improved by physical exercise, several authors
have mentioned that it could still be helpful for diabetics in
reducing the risk factors associated with coronary heart disease.
Campaigne (3) found a significant reduction in low density lipo-proteins
(LDL) among a group of adoloscents who had Type 1 diabetes and
were enrolled in a physical training program. The effects of body
weight, diet and medication was controlled in the study. A retrospective
study of 67 adults with Type 1 diabetes by Laporte (4) revealed
that those diabetics who practiced team sports in high school
and college had a lower incidence of mortality and a lower incidence
of cardio-vascular disease than their sedentary colleagues. Also,
it was observed that diabetics who participated in sports showed
no higher levels of retinopathy as had been feared.
In a critical analysis of studies
on the subject, Richter and Galbo (5) concluded that physical
training could not be recommended as a means to improve metabolic
control in Type 1 diabetes because of the difficulty in controling
glycemia among these patients. However, they specified that our
actual knowledge and techniques permit well informed subjects
to do physical exercise and to even attain very high levels of
athletic performance.
Non-Insulin Dependent Diabetes (Type 2)
As in the case of Type 1 diabetics,
Type 2 diabetics often have a lack of capacity to produce sufficient
quantities of insulin. However, among many of them, we find a
relatively normal level of production of insulin. What characterizes
Type 2 diabetics is a certain lack of sensitivity or resistance
of the tissues to insulin. This form of diabetes develops gradually
and the signs are subtle. Treatment involves the control of diet,
regular exercise, medication and in some serious cases, the administration
of insulin.
Many studies have shown the
immediate effects of exercise on Type 2 diabetes. (5,6,7) Exercise
reduces the rate of blood glucose, increases the number of insulin
receptors and increases the sensitivity and level of absorption
of insulin by the tissues. Because of its hormonal and metabolic
effects, it is believed that regular physical exercise can prevent
or stop the development of Type 2 diabetes.
In a census of studies, Zinman
and Vranic (6) concluded that exercise alone does not have an
important effect in improving over the long term, the metabolic
anomalies associated with Type 2 diabetes. As Type 2 diabetics
are particularly subject to the complications of arterio-sclerosis,
the beneficial effects of physical activities on circulating lipo-proteins
are indicated in particular. Among obese Type 2 diabetics, exercise
may even be an effective therapeutic tool favoring the loss of
weight and the absorption of insulin of the tissues.
Richter and Galbo (5) concluded
that the practice of regular physical exercise among persons genetically
predisposed to Type 2 diabetes could prevent its development,
probably by diminishing the demand placed upon the beta cells
of the pancreas. The authors added that it is not known actually
whether physical exercise can reduce morbidity or mortality rates
among diabetics. It is known, however, that physical training
can reduce certain risk factors related to the development of
arterio-sclerosis, but to a lesser degree than among healthy persons.
Recommended physical activities for diabetics
These recommendations must
be addressed to persons whose diabetes is being controlled. One
of the most important preoccupations for the diabetic is to maintain
a normal level of glycemia. Eating food brings an increase in
blood glucose while physical activity, insulin, and oral hypoglycemiants
exercise an opposite effect. The diabetic who exercises must know
how to adjust the different factors in function of their cumulative
impact on his or her glycemia. The diabetic must be able to measure
his glycemia using an appropriate device.
Among Type 1 diabetics, Nadeau
(8) mentions that for a glycemia above 300 milligrams per decilitre
(mg/dl) outside of the period immediately following a meal, the
insulin deficit is particularly serious. Therefore, in such cases,
physical exercise is not recommended because it could aggravate
the metabolic disorder. If the glycemia is normal (70-130 mg/dl),
exercise could be done if certain precautions are followed to
avoid hypoglycemia. Before physical exercise of medium length,
that is, less than one hour, the diabetic should consume rapidly
assimilable glucides in the form of fruit juice, honey or dextrose
tablets. In the case of vigorous physical activity for a longer
period, such as cross country skiing, on should take every 30
minutes a drink containing glucides and proteins (yogurt for example).
The diabetic should never go more than two hours without eating.
In the case of vigorous physical activity for a long period, one
should reduce the insulin dosage before the exercise. Such a diminished
dose would be 10 to 30 percent of the normal dosage, and would
vary greatly from one person to the other. The dosage should be
evaluated by the attending physician.
Exercise increases significantly
the metabolism of the muscles involved. If insulin is injected
into a muscular zone where being greatly exercised, it will be
quickly absorbed. To favour a more gradual absorption, it can
be injected at the level of the abdomen. (5,6,8,9)
In healthy persons, vigorous
physical activity increases greater sensitivity and absorption
which manifests even several hours after the exercise. This phenomena
is found also among insulin-dependent persons. Consequently, such
a person should never sleep down after a vigorous physical activity
without having taken a good meal, because of the risk of delayed
hypoglycemia which can manifest several hours later. (8,9) It
is especially important for patients who take not only insulin,
but beta-blockers, since the symptoms of hypoglycemia, such as
abnormal fatigue and incoherent speech and movements, can be hidden
by this type of medication. The table indicates the principal
recommendations regarding physical exercise for diabetics.
In summary, the regular practice
of physical activities and exercise can have beneficial effects
for diabetics. In the case of those with Type 2, often obese,
exercise favours the loss of weight, increases the absorption
of one's own insulin and diminishes the need for oral hypoglycemiants.
For persons with Type 1, exercise seems to bring little improvement
to the metabolic control of diabetes, but reduces certain risk
factors related to the heart. Diabetics must be aware of the possible
problems which can arrive during or after exercise and know what
to do about them.
Table 1: Recommendations Regarding Physical
Activities And Exercise Among Diabetics
1. The diabetic must be know
how to recognize the signs of hypoglycemia and when possible,
be accompanied by someone who can go and get glucides when needed.
This person must know how to intervene in case of problems.
2. Generally, the diabetic can
prevent hypoglycemia by:
- measuring more frequently
his or her level of blood glucose during the first phase of exercise;
- diminish his or her dosage of insulin (by one or two units or
according to the recommendations of their doctor) or increase
the consumption of glucides (by ten to fifteen grams per half
hour of exercise) before beginning to exercise;
- inject insulin in a zone of the body which is not affected much
by the exercise, for example, the abdomen;
- avoid exercise during the period when insulin levels are highest,
that is during the hour following a meal;
- consume drinks rich in glucides, before and during all prolonged
physical activities.
3. Because of the risk of micro-angiopathy
and neuropathy which can be instigated by a prolonged period with
high blood glucose, it is important to take good care of the feet
and wear comfortable shoes.
4. Physical activities like
bicycling and swimming are particularly indicated because they
involve much less orthopedic risks.
5. The frequency of exercise
sessions should be between five and seven times per week. For
Type 1 diabetics, daily physical activity will permit one to adopt
a regular diet and regular insulin dosage. For Type 2 diabetics,
physical activity practiced at least five times per week will
permit the maximum expenditure of calories and the control of
body weight.
6. The duration of the sessions
should be between 20 and 30 minutes for Type 1 diabetics and from
40 to 60 minutes for Type 2 diabetics.
7. The intensity of the activity
should be moderate, that is between 50 and 75 percent of the person's
functional capacity (see the calculation of the Karvonen equation:
the target heart rate should be 220 - ones age in years - heart
rate while resting x 75% + heart rate while resting). When it
is difficult to measure this, the optimal level is where one feels
slightly out of breath, but capable of holding a conversation
without much problem.
8. Patients who suffer advanced
retinopathy should avoid activities where there are repetitive
shocks (such as running and jump rope) or where there are significant
increases in arterial tension. Swimming is especially recommended.
9. Some activities such
as aerial sports or underwater diving is to be avoided among Type
1 diabetics because of the catastrophic consequences which hypoglycemia
can bring.
8. Sources: American College
of Sports Medicine, reference 9, Nadeau, reference 8, and Richter
and Galbo, reference 5.
The
Effects of Exercize and Yoga on Diabetes Part 2
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