Background and Purpose

As an exercise physiologist (Ph.D. 1995) at the University of Pittsburgh, I will participate in the Antarctic expedition to the South Pole to help raise money and awareness for type I diabetes. Along with participating in the expedition itself, I propose to perform important physiological research with the willing volunteers in the expedition. Since we only have a limited number of potential participants in this research, the information will be descriptive in nature, but nevertheless important from at least two different perspectives. First, little information exists about the rigors of physical activity in extreme cold environments with regard to physiological demands, physiological and body composition changes, and nutritional requirements. Moreover, no information such as this exists in a type I diabetic such as Will Cross, who will be taking a lead role in this expedition. Perhaps most importantly, we will demonstrate that persons with type I diabetes, who are adequately trained, are quite capable of performing such feats as a trek to the South Pole. Moreover, the research performed during this expedition will provide a unique opportunity to determine how insulin requirements change during physical activity in an extreme environment. The hypothesis to be tested is that a type I diabetic will have similar physiological responses during this expedition as a non-diabetic. Thus, both the participation in the expedition itself and the physiological research will undoubtedly raise awareness about this disease.

Preliminary Research Conducted for a North Pole Expedition

In order to determine the feasibility of Polar travel for someone with type 1 diabetes, and to approximate energy requirements for such extreme activity to be performed for the Ultimate Walk, we conducted some preliminary research in conjunction with an expedition to the North Pole during the Spring of 2001. One man (WC) with type 1 diabetes (T1DM) and one man (JP) without diabetes (NOND) participated in this expedition, the same men who will be participating in the Ultimate Walk during the Antarctica Summer (November 2002 to February 2003). Using a graded exercise test on a treadmill, we measured physical fitness before and after the 11-day expedition at our Exercise Physiology Laboratory at the University of Pittsburgh. Physical fitness increased by approximately 10% in both men as determined by their submaximal exercise heart rate and oxygen consumption responses. A major focus of this preliminary Polar research was to determine the energy requirements for each of these men during such extreme activity as pulling 60 kg sledges for an average of 14 hours per day for 11 days. We measured body weight and total body fat before and after the expedition. Physical activity energy expenditure was determined from the mean oxygen uptake (VO2) estimated from the heart rate-VO2 relationship obtained during a sub-maximal treadmill test performed 2 days prior to the trek. The two men kept detailed food records so that the dietitian could calculate the total energy consumption (calories per day). Figure 1 illustrates that WC consumed approximately 5,000 Kilocalories per day over the 11-day expedition, while JP consumed only half that amount. However, JP expended approximately 8,000 Kilocalories per day, while WC expended approximately 6,000 Kilocalories per day. The greater energy expenditure in JP was most likely attributed to his greater muscle mass. Accordingly, JP was unable to keep with his energy demands and therefore lost more weight and fat mass during the expedition compared to WC (Figure 2). We concluded that individuals with type 1 diabetes who are prepared and physically fit are quite capable of high level physical activity in an extreme environment. An abstract of this research will be presented in May 2002 at the American College of Sports Medicine annual meeting in St. Louis and has been included as an appendix. This research will be invaluable to help determine food requirements during the Ultimate Walk expedition to the South Pole.

Research Plan for the Ultimate Walk expedition to the South Pole

Three men will participate in this physiological research. One man has type 1 diabetes and the other two do not have diabetes. We will examine the changes in several parameters of body composition, metabolism, fitness, and muscle function before and after the expedition to the South Pole. We routinely perform very complex assessments of energy metabolism and body composition of patients with diabetes and in non-diabetics at the University of Pittsburgh. These methods are described in more detail below. Briefly, we will be able to determine changes in body fat and muscle mass, changes in muscle fatty acid and glucose metabolism and changes in overall energy expenditure.

Insulin Requirements:
Will Cross will keep strict records of his insulin requirements over the course of the expedition. It has been well established that insulin requirements are generally reduced during periods of physical activity. However, it is unclear how such extreme activity combined with an enormous calorie intake will affect insulin requirements in a person with type 1 diabetes. Therefore, one purpose of the research for the Ultimate Walk will be to determine how insulin requirements change during extreme physical activity.

Physical Fitness:
We will measure changes in physical fitness (aerobic capacity) with a measure of maximal oxygen consumption during maximal exercise. This will be done with a maximal graded treadmill test. This treadmill test will consist of a 5-minute warm-up at 2.5 mph with no grade. The speed will then increase and stay constant at 3.4 mph but the grade will increase 2% every two minutes until volitional exhaustion or one of the established criteria for VO2 max have been reached: an RER >1.15, HR max = age predicted (220-age) or a plateau in the VO2 work rate curve (American College of Sports Medicine Guidelines). Heart rate, blood pressure and ECG will be recorded prior, during, and immediately following this test. Subjects will breathe through a mouthpiece connected to a two way breathing valve (Hans Rudolph, Kansas City, MO) during the test, and expired air will be collected into a mixing chamber interfaced to a computerized metabolic cart (Sensor Medics cs 2900, Yorba Linda, CA) to measure expiratory flow and expired air for CO2 and O2 fractions. The metabolic cart will analyze the data for O2 consumption (VO2) every 30 seconds. In addition to the above criteria, the exercise test will be stopped if the subject has either signs and/or symptoms of CVD complications, e.g. hypotensive response to exercise. Advanced Cardiac Life Support (ACLS) certified personnel and/or physician will supervise all graded exercise tests. Subjects will repeat the graded exercise test during visit four following the expedition.

Muscle Strength:
Muscle strength of arms and legs will be measured before and after the expedition using isokinetic dynamometry (KinCom).

Body Composition:
A Dual Energy X-Ray absorptiometry (DEXA; Lunar Corp., Madison, WI) scan will then be used to measure total body fat mass and fat free mass. This test will be administered by a certified technician. Magnetic Resonance Imaging (MRI) scans will be performed before and after the expedition to precisely and accurately quantify muscle and fat volumes in the arms and legs. MRI scans will be performed o a 1.5 Tesla magnet approved for human use in onjuction with the University of Pittsburgh Magnetic Resonance Research Center directed by Dr. Fernando Boada.

Fat and Glucose Metabolism, Energy Expenditure and Energy Consumption:
Following an overnight fast, subjects will arrive at the Pittsburgh General Clinical Research Center (GCRC) and will be placed under open circuit spirometry metabolic analysis apparatus (Delta Track, SensorMedics, Yorba Linda, CA) laying still on a bed for 20 minutes to determine their resting metabolic rate. This test will also allow us to calculate based on whole body gas exchange measurements how much fat and glucose calories that the men consume at rest. This rest will be performed before and after the expedition in order to determine how the resting metabolic rate and fat and glucose metabolism change as a result of this extreme expedition. In addition to measuring changes in body composition, metabolism and function, we will measure energy expenditure during the expedition with wireless heart rate monitors and non-radioactive (stable) isotope dilution methods. A measure of total energy expenditure will be performed using the doubly labeled water method in conjunction with Dr. Dale Schoeller at the University of Wisconsin. In conjunction with these physiological variables we will measure the total caloric intake and macronutrient composition, i.e. % fat, carbohydrate and protein of the diets during the expedition by detailed food records. These Polar travelers will consume a diet consisting of approximately 50-55% fat, 15% protein and 30-35% carbohydrates. This information will enable us to determine the extent to which energy expenditure and caloric intake were matched during this extreme event, and how much body fat and protein is lost to account for the deficit in energy expenditure and food intake.

What new data will result from this research?
Medical research will play a key role in the success of the Antarctic expedition, 'The Ultimate Walk to Cure Diabetes'. Researchers from the University of Pittsburgh will answer crucial questions concerning the physiological demands of exercise in a cold, extreme environment in individuals with type 1 diabetes. Examples of such questions to be answered are: Is someone with diabetes able to eat enough, as well as burn enough fat for energy in order to sustain the rigors of polar travel? Can someone with diabetes maintain adequate energy balance so that he will not lose too much weight? What impact will the loss muscle have on strength, muscle fatigue and metabolism in a person with diabetes? In brief, data collected before, during and after this expedition will provide novel information about the physical demands of the journey, including the amount of energy that is required for such extreme activity. Recent data from a 11-day North Pole training trip during the Spring of 2001 suggest that individuals with type 1 diabetes who are prepared and physically fit are quite capable of high level physical activity (over 5,000 calories per day!) in an extreme environment. However, more detailed research is necessary to determine whether or not it is possible for diabetics to maintain energy balance for longer periods in such extreme conditions.

What impact will this research have within the diabetes community?
Research resulting from this expedition should have two fundamental effects: Information about changes in body weight, muscle mass, metabolism and muscle function may be used by health care providers to help their patients with diabetes. Specifically, they may be better able to make educated decisions about participation in endurance sports and extreme activities such as marathon running, triathlon, mountain climbing and hiking. From our research it should be possible to tell children and young adults with diabetes the physical fitness and energy requirements of these sports and activities. Ultimately, this research should translate directly into another tangible benefit to patients with diabetes, which would be to aspire them to being more physically active. An interesting analogy can be made here. Very few young children will ever become astronauts. However, millions of children are motivated by what it could be like to explore outerspace. The same can be said for the 'The Ultimate Walk to Cure Diabetes'. Although most children with diabetes will never participate in such extreme activities, knowledge and awareness of those who have may provide the motivation for them to pursue more physical activity in their daily lives and to live more healthy lifestyles, undoubtedly contributing to their enhanced quality of life.

APPENDIX
Abstract of North Pole Research to be presented in May 2002 at the American College of Sports Medicine annual meeting in St. Louis.