PE Oxygen uptake at rest, physical activity and recovery

What is the primary role of oxygen uptake (VO2) during exercise?

• Transport, uptake, and utilization of oxygen for energy production
• Elimination of carbon dioxide
• Cooling down the body
• Increasing heart rate
• Preventing muscle fatigue

Answer explanation

VO2 refers to the oxygen transported, taken up, and used for ATP production.

Why does oxygen uptake increase in a linear fashion with exercise intensity?

• The body requires more oxygen to perform at higher intensities
• The respiratory system cannot adjust
• The body uses only anaerobic energy
• Heart rate remains constant
• The body stores large amounts of oxygen

Answer explanation

Oxygen demand rises with intensity, requiring a proportional increase in uptake.

What determines the maximum level of oxygen uptake (VO2 max)?

• The efficiency of the cardiovascular and respiratory systems
• The amount of stored oxygen
• The body's lactate levels
• The temperature of the muscles
• The percentage of fast-twitch muscle fibers

Answer explanation

VO2 max is the point where oxygen supply can no longer increase despite rising demand.

How does oxygen uptake compare at rest and during maximal exercise?

• It increases from approximately 0.25 L/min to around 2–3.5 L/min
• It remains the same
• It decreases due to muscle fatigue
• It fluctuates randomly
• It is only dependent on tidal volume

Answer explanation

Oxygen uptake rises significantly from rest to maximal exercise.

Why does oxygen deficit occur at the start of exercise?

• The circulatory and respiratory systems take time to meet oxygen demand
• The body only uses anaerobic pathways at the start
• Oxygen is stored in large amounts in muscles
• The lungs take time to expand
• The heart rate decreases initially

Answer explanation

Oxygen deficit occurs because oxygen supply lags behind demand at the beginning.

How does the body compensate for oxygen deficit?

• Increased reliance on anaerobic energy systems
• Decreased ATP production
• Increased tidal volume
• Decreased heart rate
• Increased oxygen storage in muscles

Answer explanation

Anaerobic pathways provide ATP during oxygen deficit until aerobic supply catches up.

What is the key physiological reason for steady state being achieved?

• Oxygen supply meets oxygen demand
• Heart rate plateaus
• The body stops producing lactate
• Anaerobic energy is no longer used
• The respiratory rate slows down

Answer explanation

Steady state occurs when oxygen delivery matches demand, reducing anaerobic reliance.

What happens if exercise intensity increases after a steady state is reached?

• Oxygen deficit occurs again
• Oxygen supply remains the same
• Anaerobic metabolism is no longer needed
• Heart rate decreases
• VO2 max is instantly reached

Answer explanation

A new oxygen deficit occurs until the body adjusts to the increased demand.

Why does EPOC occur after exercise?

• The body needs extra oxygen to restore ATP and CP levels
• The respiratory system stops working
• Blood oxygen levels drop significantly
• Oxygen is stored in muscles for later use
• VO2 max is exceeded

Answer explanation

EPOC helps restore energy levels and remove byproducts like lactate.

What is a major contributor to the duration of EPOC?

• Elevated muscle temperature and ATP restoration
• Decreased respiratory rate
• Decreased heart rate
• The presence of glycogen in muscles
• The time spent resting after exercise

Answer explanation

EPOC duration is influenced by factors like body temperature and ATP resynthesis.