Exercise and Heart Rate

Linked to B4: Bioenergetics

Aim

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

Practical Guide

Method & analysis

Exam Questions

Past-paper style

Mark Scheme

Model answers

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

✓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

★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