The Effects of Excersize
and Yoga on Diabetes: A Survey of Medical Research
by Marshall Govindan, M.A. and Dr. Emilia
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
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
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
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 adolescents 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 controlling
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
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 deciliter ( 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, one 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 favor 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 favors
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.
Recommendations Regarding Physical
Activities And Exercise Among Diabetics
1. The diabetic must 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
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
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
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. Sources: American College of Sports Medicine, reference
9, Nadeau, reference 8, and Richter and Galbo, reference 5.