Exam 1 Study Guide Questions

Know the effect of exercise on enzyme activity.

Exercise changes enzyme activity through both acute activation and chronic adaptation. Enzymes also control the rate of metabolism and energy production. When enzymes speed up a reaction, they lower activation energy. Our normal body temperature is 37 Celsius; When body temperature increases, enzyme activity will also increase. Our normal pH is 7; when pH becomes more acidic, it will decrease enzyme activity.

Know the importance of ATP.

ATP is a usable source of energy that can be used immediately for all body functions, mostly in muscle contraction. It is important to human movement because it is the main energy source.

Know the energy sources for ATP resynthesis.s

Phosphocreatine [PCr] - stored in muscle cells (cytoplasm) & in small amounts 

Glucose [Sugar] -  no high-energy bonds, stored in muscles, liver, and blood, and fuel for high-intensity exercise; for muscle + liver stored as glycogen. 

Triglyceride - has a large amount of energy for ATP resynthesis, stored in Adipose tissue & in muscles  Proteins - can be used but not usually when it's the main energy for starvation & extreme exercise.

Know the energy pathways for ATP resynthesis

Phosphocreatine (PCr) Pathway 

Glycolysis 

Oxidation - Krebs Cycle & Electron Transport Chain

ATP-PCr Pathway: Energy source(s), cell location, # of reactions, ATP yield, end product(s)

• Energy Source: Phosphocreatine 

• Cell location: cytoplasm 

• Time to turn up: Immediately 

• # of reactions: 1 

• ATP yield: 1PCr = 1 ATP. 

• Maximal rate of ATP resynthesis is about 15 sec or 10 ATP/sec. 

  • End Product: Creatine + Pi

Glycolysis: Energy source(s), cell location, # of reactions, ATP yield, end product(s)

• Energy Source: glucose; glycogen  

• Cell location: cytoplasm 

• Time to turn up: 5 sec 

• # of reactions: 10  

• ATP yield: 1glucose  = 2  ATP. 

• Maximal rate of ATP resynthesis is about 1 min. 

  • End product: Pyruvate & NADH

Oxidation: Energy source(s), cell location, # of reactions, ATP yield, end product(s)

• Energy Source: Glucose, Triglycerides, carbohydrates & fats 

• Cell location: Mitochondria 

• # of reactions: Many 

• ATP yield: 38 ATP 

• Maximal rate of ATP resynthesis is about 90 min. 

  • End product: CO2 + H2O

Know the role of oxygen in energy metabolism and the location of this role

The role of oxygen in energy metabolism is used to oxidize carbohydrates and fats to produce ATP.  Oxygen is the final electron acceptor on the electron transport chain. 

Understand how energy systems interact during exercise

The “Interaction of energy systems during exercise” is that the three energy systems are always on, and they don’t work independently of one another. Each of the energy pathways will contribute to the exercise depending on intensity and how long you go.

Know the power and capacity of each energy system.

When at rest, oxidation is active with triglycerides as the energy source. When doing light exercise, oxidation is still active, with triglycerides as the energy source. When doing moderate/heavy exercise, oxidation is still active with glucose as the energy source. When doing severe exercise, PCr and glycolysis are active, with PCr and glucose as the energy sources.

Know how the creation of lactate benefits exercise

Lactate benefits exercise: 1) it extends the maximum glycolysis, and 2) its fuel source that can be converted back to pyruvate or glucose and oxidized.

Know the O2 deficit

Oxygen deficit is when you increase the intensity of the exercise upwards or at the beginning of the exercise; O2 cannot meet the immediate energy demand. So, Anaerobic pathways (PCr & glycolysis) fill up the energy need for the first few minutes before oxidation takes over.

Know the EPOC

Is the extra oxygen that our bodies need for recovery after exercise, to repay the O2 deficit and return to our resting state.

Know the metabolic basis for fatigue

10 Sec duration: PCr depletion, recovers in 2-5 min 

60 sec duration: Lactate accumulation, recovery takes a couple of minutes (8-20 min 

1 hr duration: Depletion of glycogen 

Know how increasing intensity and increasing duration affect the energy source for ATP 

resynthesis during exercise

• Higher intensity: More carbohydrates and anaerobic energy systems.

  • Longer duration: More aerobic metabolism and fat use, along with glycogen depletion

Know how the effect of hormones is controlled.

Exercise intensity and duration control how much hormones are released to provide energy.

 Hormonal control of energy metabolism – release of stored energy

-  Epinephrine: ↑ glycogen breakdown and fat breakdown.

-  Glucagon: ↑ liver glucose release.

 - Insulin: ↓ during exercise, allowing more stored energy to be released.

Know the hormones responsible, their targets, and their effects

Glucagon: Target tissue: Liver & Adipose tissue 

Responses: Glycogenolysis, Gluconeogenesis, Lipolysis

Epinephrine: Target tissue: Liver, Adipose tissue

Response:  glycogenolysis, lipolysis

Norepinephrine: Target tissue: Liver, Adipose tissue 

Response: glycogenolysis, lipolysis

Cortisol: Target Tissue: Liver & Adipose tissue 

Response: Gluconeogenesis, lipolysis

Growth hormone: Target Tissue: Liver & Adipose tissue 

Response: Gluconeogenesis, Lipolysis

Know that muscle stores of energy have primarily local control

Regulation of energy stored in muscle is by local changes (chemical changes in muscles) 

Acute exercise – changes and explanation for changes

When intensity increases, the hormone concentration will increase, which will increase the energy that is needed. When duration increases, the hormone concentration will increase because the longer the duration, the more you run low on muscle energy and transition to blood energy.

Chronic exercise (adaptation) – changes and explanation for changes

With training, hormone response will decrease compared to acute exercise, which will increase hormone receptors and increase energy stores.

Know the effect of exercise on glucose uptake and insulin sensitivity

As insulin decreases during exercise, muscle glucose uptake increases.  Muscle contraction stimulates glucose uptake and insulin sensitivity. 

Importance for diabetes:

Exercise is important for both prevention and management of Type II diabetes because it restores insulin sensitivity and activates glucose uptake independently of insulin. 

Know how hormones control water balance during: Acute exercise

Acute exercise: ↑ ADH and aldosterone → ↑ tubular reabsorption of water and sodium → less urine.

Know how hormones control water balance during: Chronic training (adaptation)

Chronic training: Improved hormone response → more efficient water and sodium reabsorption

Know how we measure energy expenditure in Exercise Physiology

Energy Expenditure is measured using indirect calorimetry.

Know how we used the method, variables measured, procedure for determining EE in Exercise Phyiso.

The equipment needed is a metabolic cart or open-circuit spirometry, a mouthpiece, and a nosepiece. The equipment measures the volume of inspired or expired air, including measuring oxygen and carbon dioxide concentrations between room air and expired air. These measures are used to determine EE by calculating the volume of oxygen uptake (VO2) and volume of carbon dioxide production (VCO2).