Aerobic Energy Production During Exercise

Aerobic Energy Production During Exercise PED 5230

Moderate Aerobic Energy • 50-85% of VO2max

Oxygen? • Fuel?

Lactate?

Moderate Aerobic Energy Oxygen Supply = Oxygen Demand...barely

Moderate Aerobic Energy • Shift towards a greater contribution from

carbohydrates. Why? • Advantage? • Disadvantage? • 2,000 versus 72,000

Moderate Aerobic Energy Grams

Kcals

Liver glycogen

110

451

Muscle glycogen

500

2050

Glucose

15

62

Total Subcutaneous and Visceral Fat Intramuscular Fat

625

2563

7,800

73,320

161

1513

Total

7961

74,833

From Wilmore and

Moderate Aerobic Energy • Goal: maintain glucose levels

Muscle • Central nervous system

Moderate Aerobic Energy • Liver glycogen

Glucagon • Catecholamines • Epinephrine • Norepinephrine

Moderate Aerobic Energy 1.0

1.5

Glycogen Depletion

Moderate Aerobic Energy • Prolonged exercise

Carbohydrates • Hypoglycemia • Glycogen Depletion

Fats and ketones • Proteins

Gluconeogenesis

Fat Burns in a Carbohydrate / Protein Flame

low pyruvate Ketones

Moderate Aerobic Energy • Ketones

acetoacetate • beta-

hydroxybutyrate • Fuel for ST fibers,

brain and nerves • Acidic

The Glucose-Alanine Cycle

Moderate Aerobic Energy Near lactate threshold

Fatigue

QuickTimeª and a TIFF (Uncompressed) decompressor are needed to see this picture.

Fatigue • ATP or P?

Glycogen depletion? • > 1-2 hours QuickTimeª and a TIFF (Uncompressed) decompressor are needed to see this picture.

• Hypoglycemia?

Direct - muscle • Indirect - CNS

Hypoglycemia

Hypoglycemia Brain (inhibit)

Heart

O2

Muscles Glycogen & Fat

low glucose Liver Glycogen

Adipose Fat

Fatigue

• Lactic acid or H? QuickTimeª and a TIFF (Uncompressed) decompressor are needed to see this picture.

• Low oxygen supply?

Oxygen / Lactic Acid Brain

Lungs

O2

Heart

O2

Muscles Glycogen & Fat

Liver Glycogen

Adipose Fat

Oxygen / Lactic Acid

Fatigue

• Central fatigue? Central drive or command •

Central governor

Central Fatigue Brain (inhibit)

Lungs

O2

O2

Heart

Muscles Glycogen & Fat

Liver Glycogen

Adipose Fat

Heavy Aerobic Energy • > 85% of VO2max

Oxygen? • Fuel?

Lactate?

Heavy Aerobic Energy • Oxygen supply less than demand

Muscles • Heart, too?

Anaerobic energy

Heavy Aerobic Energy • Fuel

Carbohydrate • Aerobic • Anaerobic • PC?

Heavy Exercise • Fatigue

Lactic acid? • CNS?

Heavy Aerobic Energy

Lactate

Heavy Exercise • If a person were to begin exercising at their

VO2max, how long would they be able to last at that intensity? Why? • What is the recommended percentage of

VO2max to exercise at?