You are the clinical exercise physiologist for a 55 year old man (DD) recently diagnosed with Type II diabetes. He is 5’ 10” (178 cm) and weighs 220 lb (100 kg); BMI = 31.6 kg/m2 with an HbA1C of 6.6%. He has no diabetes-related complications (e.g., peripheral or autonomic neuropathy), no other co-morbidities, and is taking no medications. A cardiopulmonary stress test (CPT) on a cycle ergometer reveals a normotensive exercise response and unremarkable EKG with no arrhythmias or ST segment changes. His peak HR is 160 bpm and his VO2max is 28.0 mL/kg/min with a 200 W peak.
DD is trying to improve his glycemic control and lose weight via diet and exercise. For the last four months, he has been walking at a moderate pace for 30 min x 3 d/wk on his own.
You have been working with DD for two weeks and have put him on a low carbohydrate, high fat, ketogenic diet (LCHF) in which he consumes < 20 g carbohydrate (CHO) per day. He has tolerated the diet well and has noticed that his fasting blood glucose in the morning before breakfast is now around 110 mg/dL instead of the 145 mg/dL that was typical prior to beginning the LCHF diet.
He comes to your facility to exercise four days per week at 1300 (1pm), several hours after his mid-morning LCHF meal. For the first two weeks of his LCHF diet, his blood glucose has been in the 105-110 mg/dL range at the beginning of his exercise sessions; the sessions have gone well with no symptoms or hypoglycemic responses. Today on arrival, his blood glucose is 90 mg/dL (5 mM/L) and his blood ketones are 1.5 mM/L.
Question 1: What is your exercise prescription for DD for the next several weeks? Discuss cardiopulmonary exercise (mode, duration, intensity), resistance exercise (RE; mode, duration, intensity), and range of motion (ROM) and balance training. You do not need to write a fully detailed program, but a good outline of one. Explain your thought process (e.g., if you decide to prescribe higher intensity, state what the potential benefits are and why it is an appropriate choice for this patient). I repeat: I want to know your rationale for your recommendations.
Question 2: Given all of the above information (diet, exercise history, blood glucose), does DD need to ingest supplemental CHO prior to today’s moderate intensity continuous cardiopulmonary workout and if so, how much? Again, clearly and thoroughly describe your thought process and rationale for your answer/decision—don’t simply repeat the basic recommendations from the textbook.
Be sure to provide references in your answers.
Expert Solution Preview
DD, a 55-year-old man diagnosed with Type II diabetes, is trying to control his blood glucose levels and lose weight. He has been following a low carbohydrate, high fat, ketogenic diet and exercising moderately for 30 minutes, three days a week. He has also completed a cardiopulmonary stress test, revealing a normotensive exercise response and no other diabetes-related complications. In this scenario, two questions are asked, and each one will be answered separately with a proper rationale.
Question 1: What is your exercise prescription for DD for the next several weeks? Discuss cardiopulmonary exercise (mode, duration, intensity), resistance exercise (RE; mode, duration, intensity), and range of motion (ROM) and balance training.
As DD is trying to improve his glycemic control and lose weight, his exercise routine should consist of moderate-to-vigorous intensity cardiovascular exercise, combined with resistance exercise and flexibility and balance training. Resistance exercise (RE) should focus on large muscle groups and involve 2-3 sets of 8-15 repetitions of each exercise, 2-3 times per week. ROM exercises should include stretching of major muscle groups for 10-30 seconds, 2-4 times per week. For balance training, exercises such as standing on one foot and weight shifting can be included for 10-30 seconds, 2-3 times per week.
Cardiopulmonary exercise (CPE) should be a combination of moderate-to-vigorous intensity aerobic exercise and interval training. DD has no diabetes-related complications and normal blood pressure and EKG. He has a VO2max of 28.0 mL/kg/min, which suggests that his cardiovascular health is fair. An appropriate CPE for this patient would be a 45 to 60-minute workout, three to four times per week, utilizing both steady-state and interval training at a moderate-to-vigorous intensity level.
Interval training can help DD achieve better glycemic control as it can result in a greater reduction of blood glucose levels and HbA1C compared to continuous exercise training. Interval training should consist of short bouts (30 to 60 seconds) of high intensity (80-90% of maximum heart rate) exercise, followed by a recovery period (60 to 120 seconds) at a lower intensity (50-60% of maximum heart rate).
Resistance exercise plays an essential role in helping DD lose weight as it increases lean body mass, improves glycemic control, reduces insulin resistance, and helps to maintain bone density. Combining resistance training and CPE can help DD achieve his weight loss goal by increasing energy expenditure, promoting fat loss and maintaining lean body mass.
Question 2: Given all of the above information (diet, exercise history, blood glucose), does DD need to ingest supplemental CHO before today’s moderate-intensity continuous cardiopulmonary workout, and if so, how much?
DD’s blood glucose level before his exercise session is 90 mg/dL (5 mM/L), which is within a safe range for exercise. There is no need to consume supplemental CHO before today’s workout. The blood ketone level of 1.5 mM/L indicates that DD is in a state of nutritional ketosis, which means that his body is efficiently burning fat for fuel. Consuming CHO at this point can disrupt nutritional ketosis and decrease fat metabolism, which goes against DD’s goal of losing weight. However, if DD’s blood glucose level was lower than 80 mg/dL (4.4 mM/L), he would have needed to ingest a small amount of supplemental CHO (15-30 g) to prevent hypoglycemic events during exercise.
In conclusion, DD’s exercise prescription should consist of a combination of moderate-to-vigorous intensity cardiovascular exercise, resistance exercise, flexibility, and balance training. The cardiovascular exercise should incorporate interval training to help improve glycemic control. Nutritional ketosis allows DD to burn fat efficiently, and there is no need to supplement CHO before the workout.