Training Clients With Diabetes
Jeffrey
Janot, M.S. and Len Kravitz, Ph.D.
Introduction
The incidence of diabetes mellitus, a
metabolic disease, is a growing problem in the
American population. To date, 16 million Americans have diabetes, either
known or unknown, with 1,700 new cases being diagnosed everyday (Nieman
1998). Diabetes has been linked to the development of a variety of diseases
including heart disease, stroke, peripheral vascular disease, and
neurological disorders. The cause of death in individuals with diabetes is
not the disorder itself, but from the diseases associated with it, most
notably heart disease. Diabetes is classified into two categories: Type I
and Type II. Typically, Type I diabetes occurs in younger individuals (not
always!) and comprises approximately 10% of all diabetic cases. Thereby,
90% of the cases are Type II, which is most common in older individuals.
Effective management and prevention strategies for diabetes are of utmost
importance. As exercise professionals, you can play a crucial role within
these strategies, working collaboratively with other skilled health
professionals. It should be noted that there are a number of opportunities
for personal trainers to enhance their professional knowledge, such as
obtaining clinical-type certifications (ACE clinical exercise specialist,
ACSM exercise specialist, etc.).
This article will present recommendations and clinical considerations for
the development of a safe strength training program for individuals with
diabetes. A brief discussion of the pathophysiology behind diabetes will be
presented first, followed by specific exercise prescription guidelines for
strength training. In addition, Table 1 summaries some cardiorespiratory
guidelines according to frequency, intensity, time and type (FITT) for the
client with Type I and Type II diabetes.
Pathophysiology of Type I and Type II
diabetes
The pancreas is the insulin-producing organ in the body. Insulin is made
and stored in specialized cells within the pancreas and is released by
various signals that are sensitive to the intake and digestion of food. In
Type I diabetes, the specialized cells in the pancreas that produce insulin
are destroyed, so that the production of insulin cannot occur in these
individuals. In Type II, the specialized cells are able to produce insulin,
but the insulin is ineffective at helping blood sugar (glucose) to enter
the body tissues (most notably skeletal muscle) that need it for producing
energy. This condition is called insulin resistance. In general, a normal
resting blood glucose level ranges from 70 to 110 milligrams per deciliter
(mg/dl) of blood. If two or more measurements of blood glucose levels
(after a 12-hour fast) exceed 140 mg/dl, diabetes is typically diagnosed.
The causes of diabetes are somewhat different between the two types.
Heredity or a genetic pre-disposition to developing diabetes seems to be
common to both types. Other factors related to Type I are environmental
causes or viral infections that destroy the pancreas; whereas, increasing
age, race, and obesity are related to Type II. Exercise training fits into
the treatment scheme of diabetes by addressing the management of obesity.
This is where exercise professionals can make the biggest impact on the
treatment of diabetes.
Strength training research and guidelines
for diabetics
The major benefits of resistance training in individuals with diabetes are:
1) improved blood cholesterol profiles, 2) increased heart function, 3)
decreased blood pressure, 4) improved insulin sensitivity and blood glucose
control, 5) improved muscular strength, power, and endurance, and 6)
increased bone strength (Soukup et al. 1994).
Two fairly recent studies by Eriksson and colleagues (1997) and Ishii and
colleagues (1998) illustrate the benefits of strength training in the
management of diabetes. In the study by Eriksson, eight participants who
had Type II diabetes completed a 3-month progressive resistance program
that consisted of two days a week of circuit weight training. One set of
15-20 reps was completed at each station with a 30-sec rest between
stations. A variety of upper- and lower-body muscle groups were challenged.
The researchers found that circuit weight training was responsible for
improvements in blood glucose level control and that these improvements
were significantly related to training-induced muscle hypertrophy. This
study also showed that increases in muscle mass from strength training are
important in the management of diabetes, as well as decreasing the risk for
developing complications associated with diabetes.
In the study by Ishii and colleagues (1998), 17 individuals with Type II
diabetes were placed into two groups: a strength-training group and sedentary
control group. The training group participants were instructed to train
five times per week for 4-6 weeks at workloads corresponding to 40-50% of
their 1 rep max. Two sets of 10 repetitions for upper body muscles and two
sets of 20 repetitions for lower body muscles were done using the following
exercises: arm curl, military press, bench press, squats, knee extensions,
heel raises, back extensions, and bent knee sit-up. The researchers reported
that the rate of blood glucose entry into the working muscles increased
after training. This study demonstrates that moderate-intensity, high
volume training improved insulin sensitivity by 48% in these individuals.
Strength training prescription guidelines
for clients with diabetes
Determining resistance. In both groups, 1 rep maximum testing can be done
provided that the person’s diabetes is stable and has no complications that
can be affected by maximum exertion. In general, most people can tolerate
30-50% of 1 rep maximum for a workload during exercise training.
Number of sets and repetitions. 1-2 sets per exercise is a good starting point for
your client. Repetitions can be established in the same manner as you would
for an individual without diabetes. Base your prescription on the client’s
individual goals and their exercise tolerance. In general, use lower
repetitions/higher resistance for strength and higher repetitions/lower
resistance for endurance.
Rest time between sets. Using 30-60 seconds for the rest period is
appropriate in most situations. With greater intensity bouts a slightly
longer (up to 2 minutes) rest period may be necessary.
Frequency of strength training. Having your client strength train at least two days
per week is appropriate in order to see beneficial results from the type of
exercise, as shown in the study by Eriksson and colleagues (1997).
Clinical considerations for exercising the
individual with diabetes
Some considerations regarding exercise prescription involve minimizing the
risks involved with exercising individuals with diabetes. In cases where
the individual has vascular problems and/or high blood pressure, consult
the client’s physician before progressing. Also, use lighter workloads for
these individuals, as they will not increase blood pressure as much as the
higher loads. It is also important to attempt to minimize the risk of your
client for developing hypoglycemia (low blood glucose) during exercise.
Strategies such as eating 1-2 hours before exercise, eating a snack before
exercise (and possibly during), having them check their blood glucose
before exercising, and knowing the warning signs of hypoglycemia
(dizziness, anxiety, shaking, and uneasiness) will help exercise tolerance.
Knowing when to stop exercise and seek emergency care is a point that
cannot be overstated by these authors. Clients should consult their
dietitian or physician on what foods are appropriate to eat before, during,
and after exercise. Lastly, follow general exercise guidelines such as
proper warm-up and cool-down, appropriate footwear, adequate hydration, and
avoid exercising in extreme environments. Major contraindications to
exercise training with diabetics is presented in Table 2.
Summary
The main goal of the treatment of diabetes is to achieve good blood glucose
control and avoid complications related to high blood glucose (Eriksson et
al. 1997). Since exercise has an insulin-like effect on blood glucose
levels, exercise should be considered as an adjunct to the medical
management of diabetes. Strength training (when done correctly) has been
shown to provide a safe and effective way to control blood glucose,
increase strength, and improve the quality of life in individuals with
diabetes.
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