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Practical 7Spec ref: 4.4.2.2

Exercise and Heart Rate

Linked to B4: Bioenergetics

Aim

Investigate the effect of exercise on heart rate and breathing rate, and measure recovery time.

PDF Resources

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Practical Guide

Method & analysis

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Exam Questions

Past-paper style

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Mark Scheme

Model answers

Equipment

  • •Stopwatch
  • •Participants
  • •Step or raised platform
  • •Record sheet

Variables

Independent variable
Exercise intensity or duration
Dependent variable
Heart rate (bpm) and breathing rate (breaths/min)
Controlled variables
Same participant, same exercise type, same time of day, room temperature

Key Facts to Know

✓Heart rate and breathing rate both increase during exercise
✓More O₂ needed by muscles → heart pumps faster, breathing deepens
✓Lactic acid builds up during intense exercise (anaerobic respiration)
✓Oxygen debt: extra O₂ after exercise to oxidise lactic acid in the liver
✓Fitter individuals recover faster and have lower resting heart rate

⚠️ Common Mistakes

  • ✗Saying heart 'works harder' — say 'heart rate increases'
  • ✗Forgetting to record resting rates before exercise for comparison
  • ✗Confusing oxygen debt with simply needing more oxygen during exercise

💡 Exam Tips

  • ★Record resting, during and recovery rates — all three phases are tested
  • ★Recovery time = time to return to resting rate — fitter people recover faster
  • ★Oxygen debt after exercise is to break down lactic acid, not to replace O₂ used during exercise

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