RETHINKING RESISTANCE TRAINING FOR
PATIENTS WITH DIABETES

Steven Infanti

Before insulin was discovered in 1922, a tell-tale sign a person had diabetes was their inability to maintain weight. The ravages of the disease emaciated children and adults.

People with type 1 diabetes still have a difficult time keeping their muscle mass which, for most people, can be accomplished by simply going to the weight room and pumping iron. Many physicians who treat people with type 1 diabetes, however, don't recommend resistance training, because they feel it may be another health risk.

The impact resistance training can have on people with type 1 diabetes is the focus of several studies by Peter Farrell, director of the Noll Physiological Research Center. It's his hope that the research benefits people with diabetes and saves lives.

"Patients with type 1 diabetes often are told not to do resistance training, because the disease strains their microvessels and these microvessels can collapse due to increases in blood pressure. Because of that risk, physicians who treat patients with diabetes aren't in favor of having them do anything that increases blood pressure," explains Farrell.

As a result, the impact of resistance training on retaining or building muscle mass in these patients is an understudied area. There are only two published studies on this area since 1922.

"There is anecdotal evidence that suggests resistance training can help. There are football players, world class rowers, hockey players and numerous other athletes at various ages who have type 1 diabetes, but maintain their muscle mass," says Farrell. The previous two published studies on this topic didn't find any negative effects of resistance training.

The implications of Farrell's studies on muscle atrophy due to diabetes could be beneficial for all type 1 patients with diabetes. His lab subjects, however, are primarily rats. The metabolism and regulators in rats are similar to humans so much of what he learns can be applied to people. Rats offer other advantages as test subjects since they can be made diabetic artificially and, as opposed to humans, they can let the rat remain very hyperglycemic (high glucose in the blood) for long periods of time.

In order to study the effect of diabetes and resistance training on their muscles, Farrell and his researchers have the rats carry weights in tiny backpacks. By using various forms of sensory stimulus, the rats actually stand on their hind legs to reach a lever. In effect, the rats are trained to do squats, which is one of the primary muscle and strength building exercises that most people do at a health club.

Farrell used groups of diabetic or nondiabetic rats, which performed progressive resistance training for 8 weeks, performed acute resistance training or remained sedentary. He was able to demonstrate that, despite lower insulin concentrations, diabetic rats can increase muscle mass in response to the physiological stimulus. The results were that moderately diabetic animals put on muscle mass if they do resistance training.

"The next phase is to study resistance training on people with type 1 diabetes. In order to accomplish that part of the study, Farrell will need to find subjects and the Noll Physiological Research Center needs its own series of resistance training equipment.

Established in 1963, the Noll Physiological Research Center enjoys a national and international reputation as a center of excellence in applied physiology. Faculty and students from kinesiology, nutrition, and the intercollege graduate program in physiology conduct research on a wide-variety of issues. Farrell's studies are just one example of the innovative research underway in its facilities.

The resistance training research is the latest in a series of studies investigating the effects of exercise on diabetes by Farrell. Past research by Farrell showed that regular exercise training should help people with diabetes who have some remaining insulin producing capacity to increase insulin output. Until his 1991 study, the main benefit of exercise was thought to be an improvement in the capacity of the skeletal muscle to respond to insulin.

Farrell and his collaborator, Jan Ulbrecht, M.D., in the Center for Locomotion Studies, are also investigating what supplements and drinks can help avoid exercise-induced hypoglycemia in people with type 1 diabetes. People with this disease who do prolonged endurance exercise can have low glucose anywhere from 6 to 20 hours after exercise.

"People with type 1 diabetes are at the mercy of knowing their symptoms, but they can't monitor their symptoms when they're asleep. Studies have shown a moderate incidence of late onset post-exercise hypoglycemia in people who exercise on a regular basis. This drop in glucose levels while people with type 1 diabetes are asleep can cause serious problems," explains Farrell.

This is an area that hasn't received a lot of attention by other researchers. Other researchers have shown that a reduction of pre-exercise insulin dose and/or an increase in the caloric content of the pre-exercise meal are helpful for avoiding hypoglycemia. Hypoglycemia (low blood glucose) results from too much insulin or too little carbohydrate ingestion during the post-exercise period. Little information, however, is available concerning the type, amount and timing of exercise snacks for avoiding late onset post-exercise hypoglycemia (LOPEH). The study, conducted by one of Farrell's doctoral students, Jazmir Hernandez, M.D. assessed whether whole milk, water, skim milk, and two commercially available sports drinks are effective in helping a person with type 1 diabetes to avoid LOPEH. The subjects ingested the drinks before, during and after one hour of bicycle exercise in the late afternoon. The results show that persons with type 1 diabetes should use whole milk, and one of the sports drinks, which is designed for both quick and lasting nutrient replenishment.

"The results provide new information on the composition of fluid snacks for persons with type 1 diabetes who wish to exercise. To our knowledge, the effectiveness of sports drinks for helping individuals with type 1 diabetes to avoid exercise-associated hypoglycemia has not been reported," says Farrell. The study also confirms that persons with type 1 diabetes must take some form of carbohydrate containing snack before exercise or reduce their pre-exercise insulin dose if they wish to exercise safely.