Investigating the Effects of Physical Activity on Breathing

Physical activity increases the body’s demand for oxygen and results in greater production of carbon dioxide due to an increased rate of cellular respiration. This affects both the rate and depth of breathing.

Aim:

To investigate how exercise influences breathing rate and breathing depth.

Apparatus:

• Stopwatch or timer

• Exercise equipment (e.g. steps, skipping rope, space for jogging)

• Data recording sheet

• Volunteer or student subject

• Optional: stethoscope or chest strap monitor for accuracy

Procedure:

1. Measure resting breathing rate:

• Count the number of breaths per minute while the subject is at rest.
• A breath = one inhalation and one exhalation.
• Record for at least 1 full minute.

2. Physical activity:

• Ask the subject to perform light to moderate exercise for 2–3 minutes (e.g., jogging on the spot or climbing stairs).
• Begin timing immediately after exercise ends.

3. Measure post-exercise breathing rate:

• Count the number of breaths per minute immediately after exercise.
• Repeat measurements every minute for the next 3–5 minutes to observe recovery.

(Optional):

• Observe and record depth of breathing (qualitative measure — e.g. shallow, normal, deep).

Expected Results:

• Breathing rate increases significantly during and immediately after exercise.

• Depth of breathing also increases, allowing a greater volume of air to be exchanged.

• After a few minutes of rest, breathing gradually returns to normal.

Explanation:

• During physical activity, muscles require more oxygen for respiration and produce more carbon dioxide as a waste product.

• To meet this demand, the rate and depth of breathing increase, enhancing the uptake of oxygen and the removal of carbon dioxide.

• This process ensures that gas exchange at the lungs keeps up with the metabolic needs of the body.

Conclusion:

This investigation shows that physical activity causes an increase in both the rate and depth of breathing, helping the body respond to the increased demands for oxygen and removal of carbon dioxide.