Exercise Metabolism

Front 1

Define aerobic exercise.

Back 1

o prolonged, low intensity (cross country, swimming)
o moderate aerobic = can be maintained for several hours at reduced power until glycogen stores are depleted

Front 2

Define anaerobic exercise.

Back 2

o high intensity, short duration (sprinting, lifting)
o combo anaerobic = burn calories most efficiently and facilitate weight loss

Front 3

Describe the ATP & Phosphocreatine system.

Back 3

• All ATP → ADP within 4 sec of onset of exercise
• Phosphocreatine is able to donate phosphate group to ADP via creatine kinase = maintain ATP levels (short term)
• Possible since phosphocreatine exceed ATP 20:5 in muscle
• System provides max. muscle power for 20 sec
o Anaerobic glycogen- lactate system takes over
• Ex. Power lifting, shot put (burst of energy)

Front 4

Describe the glycogen- lactate system.

Back 4

• Generated energy from anaerobic glycogen break down
• Rapidly degrades glycogen → lactate via anaerobic glycolysis
• LDH catalyzes final step, regenerating NAD+ allowing anaerobic glycolysis to continue
• Lactate → fall in pH, explains onset on fatigue
o PFK1 is inhibited at acidic pH & glycolysis cease

• This system produces energy rapidly
• Flux through glycolytic pathway increases 1000-fold
• Less efficient than aerobic
o 2 ATP via anaerobic metab.
o 3 ATP via degradation of phosphorylated glucose
• provides energy between 20 seconds and 2 minutes after onset of exercise (sufficient for 200m & 400m)
• during intense anaerobic exercise of short duration = energy derived rapidly & minimal inter-organ collaboration

Front 5

Describe the Aerobic System.

Back 5

• Complete oxidation of fuel (FA, ketones, aa, and carbs)
• Prolonged aerobic → energy derived from fat (adipose) & glycogen (liver)
• System involves oxidative phosphorylation and ETC

Front 6

List carbohydrate source for exercise.

Back 6

• Preferred substrate = glucose
• Obtained via plasma glucose pool, endogenous muscle glycogen stores and hepatic gluconeogenesis

Front 7

Describe the substrate for Short duration/high intensity.

Back 7

• Dependent on muscle glycogen as sole substrate
• Does not utilize FA

Front 8

Describe the substrate Intense anaerobic.

Back 8

• 1st utilize endogenous ATP
• 2nd phosphocreatine stores
o after depeletion (4 sec of max. activity) then ATP produced via anaerobic glycolysis (emergency glycolysis)

Front 9

Outline the Cori Cycle.

Back 9

o anaerobic glycolysis produces lactate (muscle → liver for gluconeogenesis = Cori Cycle)

Front 10

Describe the substrate extended aerobic.

Back 10

• need to mobilize stored fuels rapidly
• utilizes FA (adipose via B-oxidation), glucose (CAC) and branched chain aa = substrates for ATP production
• aerobic = sustained for long periods as long as utilizing substrates from outside the exercising muscle

• early stages; most energy from carbs
• later stages; 60% from fat oxidation
o carnitine palitomyl transferase I are activated
o acetyl-SCoA carboxylase (synthesis) are inhibited
o increase lipolysis generates free FA → ketones (spares glucose for the brain)

• hepatic gluconeogenesis maintains circulating glucose
• aa metabolism (alanine) supplies substrates for gluconeogenesis & provides route for removal of ammonia (glutamine)

Front 11

Explain carbohydrate loading.

Back 11

• Maximize muscle glycogen stores
• For events lasting longer than 60-90min.
• Important to keep glycogen stores topped to prevent fatigue
• Obtain 70% of energy from carbs.

Front 12

Explain endocrine activity in exercising.

Back 12

• Circulating adrenaline, noradrenaline, glucagon, cortisol and GH are elevated
• Insulin is depressed
• Adrenaline → stimulates hepatic and muscle glycogen phosphorylase activity = glycogneolysis
• Lipolysis in fat cell are also stimulated
• Elevated cortisol promote aa mobilization from muscle protein

• Reduce levels of insulin w/ increased

Front 13

Review the contribution of exercise to maintenance of good health.

Back 13

• Cardiovascular health
• improves sleep pattern
• maintains lean muscle tissue
• reduce stress
• improves BP
• strengthens bones
• enhances insulin action