Question

1. (a) outline the role of the diaphragm and external intercostal muscles as a yoga practitioner breathes in, causing air to rush into the lungs. 2

(b) a sedentary individual undertakes a 12 - week aerobic training programme. identify the changes observed at the end of 12 weeks in:
(b.i) heart rate 1
(b.ii) stroke volume 1

Explanation:

(a) When a yoga - practitioner breathes in, the diaphragm contracts and moves downward, increasing the vertical dimension of the thoracic cavity. The external intercostal muscles contract, lifting the rib - cage and increasing the horizontal dimension of the thoracic cavity. This increases the volume of the thoracic cavity, decreasing the pressure inside it relative to the atmospheric pressure, causing air to rush into the lungs.
(b.i) After 12 - week aerobic training, the resting heart rate typically decreases. This is because the heart becomes more efficient at pumping blood, so it doesn't need to beat as frequently to meet the body's oxygen demands.
(b.ii) After 12 - week aerobic training, stroke volume increases. The heart muscle becomes stronger and more elastic, allowing it to pump out more blood with each beat.

Answer:

(a) Diaphragm contracts and moves down, external intercostal muscles contract to lift rib - cage, increasing thoracic cavity volume and causing air to enter due to pressure difference.
(b.i) Decreases.
(b.ii) Increases.