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Disclosure of Financial Relationships
DIABETES AND EXERCISE PHYSIOLOGY Anne Peters, MD Professor, USC Keck School of Medicine Director, USC Clinical Diabetes Programs
Challenges for Athletes with Diabetes • Varying workouts—type/duration/intensity • Different responses to training vs competition
Consultantship Abbott Diabetes Care BD Janssen Lilly Medscape Medtronic Minimed NovoNordisk Sanofi Takeda
Speakers Bureau BMS/AstraZeneca NovoNordisk
Exercise Physiology 101 • Muscles use glucose as primary energy source
initially—this comes from muscle glycogen stores
• Unpredictability
• Once these sources are depleted there is a balance
• Risk for hypoglycemia
between glucose production (mostly from hepatic glycogenolysis) and glucose uptake by exercising muscle. • Immediately post-exercise there is a rapid decrease in catecholamines and increase in insulin levels with restoration of muscle glycogen
• Impact of hyperglycemia on performance • Physical factors (sweat/water/heat/cold) • Everything else that impacts athletes without diabetes…
Gallen IW et al. Diabetes, Obesity and Metabolism 13:130-136, 2011
The Problem • Savanah wants to train for a 10 K. She starts to train. • She tests her BG pre-exericse which is 105 mg/dl. Ate 35 g CHO.
No insulin. Waits to work out. • 1 hour later BG = 240 mg/dl. Suspended pump. Four mile walk/jog. • 15 mins after exercise BG = 102 mg/dl. Ate 10 g CHO. • 15 minutes later BG = 144 mg/dl. Ate 30 g CHO in a snack and gave 3.4 units insulin. Time = 4 PM.
The Problem • 6 pm (2 hours later) BG = 45 mg/dl. Ate 100 g CHO (she
notes: overate due to hunger/workout/poor choice). • Waited for 30 mins and gave 8.1 units. • 10 PM = 133 mg/dl. • 11 PM = 46 mg/dl, felt nauseated, ate 30 g CHO. • 11:15 PM = 59 mg/dl. • 11:30 PM = 35 mg/dl. Ate 30 g CHO.
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The Problem • Midnight BG = 90 mg/dl, 12:15 am = 88 mg/dl. • Afraid to sleep. Suspends pump for 2 hours. • 2:30 AM BG = 355 mg/dl. Suggested dose = 4.7 units. She
gave 3.5 units.
The Problem • Total extra CHO due to lows = 230 g • Total extra calories due to lows = 920 • Total impact on confidence = huge
• 7 AM BG = 297 mg/dl. Suggested dose = 3.7 units, she gave
3.3 units. • 10 AM BG = 66 mg/dl. 15 g CHO. • 10:15 AM BG = 68 mg/dl. 30 g CHO. • Noon = 110 mg/dl.
Nondiabetic Athletes’ Fuel Focus: Carbs Providing adequate fuel to muscle May cycle carbohydrate intake during phases of training • Carbohydrate loading (3 days of a carbohydrate intake of 8-12 g/kg/day or 70 – 85% of total caloric intake with a taper in training) can double muscle glycogen • To replete glycogen stores: CHO intake of ~1.0–1.5 g/kg BW (0.5–0.7 g/lb) during the first 30 min after exercise and every 2 h for 4–6 h.
Carbohydrate Requirements for Exercise
• •
CHO recommendation (g/kg/day)
Very Light Training
3-5
Moderate intensity for 1 hr/day
5-7
Mod to high intensity for 1-3 hr/day
7-10
Mod to high intensity for 4-5 hr/day
10-12
Gallen IW et al. Diabetes, Obesity and Metabolism 13:130-136, 2011
Muscle Glycogen and Training
Muscle Glycogen Level (mmol kg)
Typical Training Day Meal for Michael Phelps
Training Load
Time (Days) Ryan M. Sports Nutrition for Endurance Athletes
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Barriers to Physical Activity Among Patients With Type 1 Diabetes
Causes of Hypoglycemia During Exercise • Inability to reduce basal insulin levels during exercise
CONCLUSION— Fear of hypoglycemia is the strongest barrier to regular physical activity
• More rapid insulin absorption • Inadequate carbohydrate intake • Insulin sensitivity variable pre/during/post exercise • Both acute and delayed (up to 24 hours)
hypoglycemia may occur Diabetes Care 31:2108–2109, 2008
Biphasic Effect of Exercise on Glucose Requirements in Adolescents with T1 DM
Fat Free Chocolate Milk as Post-Exercise Drink
Euglycemic Clamp Study
June 4, 2011 -- Fat-free chocolate milk beat out carbohydrate sports drinks at helping to rebuild and refuel muscles after exercise, researchers report. The combination of carbohydrates and protein in low-fat chocolate milk appears to be "just right" for refueling weary muscles, says William Lunn, PhD, an exercise scientist at the University of Connecticut.” It's not just a dessert item, but it's very healthy, especially for endurance athletes.
McMahon SK, Ferreira LD, Ratnam N, Davey RJ, Youngs LM, Davis EA, Fournier PA, Jones TW. JCEM 92:963-968, 2007
Fat Free Chocolate Milk as PostExercise Drink • 8 male runners, ate a balanced diet for two weeks. • At the end of each week, they took a fast paced, 45-min run. • Following each run, the men drank either 16 ounces of fat-free chocolate milk or 16 ounces of a CHO-only sports beverage with the same number of calories. • Post-exercise muscle biopsies showed increased skeletal muscle protein synthesis after the milk drink, compared with the carbonly beverage. • Additionally, drinking fat-free chocolate milk led to a higher concentration of glycogen, or muscle fuel, in muscles 30 and 60 minutes after exercise, compared with the sports drink. • Findings were presented at the American College of Sports Medicine.
WebMD
Moderate Intensity Vs. Intermittent High Intensity Exercise In Type 1 DM
Guelfi KJ, Jones TW, Fournier. Diabetes Care 28:1289-1294, 2005
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• Patients with type 1 diabetes on ultralente insulin and preprandial lispro insulin were studied. • 90 minute postprandial exercise for 30 - 60 minutes at 25%, 50% and 75% VO2max was performed • Insulin doses given at 100%, 50% or 25% of the current dose of lispro (~1 unit/10 g CHO)
Change in glu from baseline (mg/dl)
Results: One Example
Adjustments for Exercise
Exercise at 50% VO2max for 30 min
100
50 50% LP 100% LP
0
-50
-100 0
30
60
90
120
150
180
Diabetes Care 24:625-630, 2001
Guidelines for the reduction in premeal RA dose Exercise Intensity (%VO2max)
25 50 75
Available Technologies
% Dose Reduction 30 min 60 min exercise exercise 25 50 75
Can technology help?
50 75 ---
CGM: Dexcom Gen 4
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The Value of Continuous Glucose Monitoring
Sensor Rate of Changed Guided CHO Algorithm for Exercising Youth with T1DM
