Q: Why are people with high blood pressure discouraged from doing exercises that involve lifting weights (isotonic)? What is the mechanism by which aerobics, walking and swimming help in reducing blood pressure?
A:
Dr Vijaya Bharat
Isotonic exercises are high intensity activities for a short duration, like weight lifting. The contracting muscles exert pressure on the arterioles causing increased peripheral vascular resistance which necessitates the heart to pump more forcefully. Increased contractility of the heart muscle and increased vascular resistance increase the blood pressure. Therefore isotonic exercises are to be avoided by those with high blood pressure.
Aerobic exercises like walking, swimming and cycling start gradually and remain sustained for a longer time. This causes dilatation of the arterioles in the muscles in order to supply more blood to the exercising muscles. By increasing the venous blood flow from legs to the heart and by reducing the resistance in the arterioles, the heart is able to pump blood with ease. Regular aerobic exercise reduces blood pressure and improves cardiac function.
This week’s questions
- Unlike when connected directly to an electrical socket, why does it take a long time to charge a mobile phone when connected to a computer through USB?
- What is fast charging seen in certain mobile phones? Does fast charging reduce the longevity of the battery?
- What is the force that drives blood flow from the limbs to the heart against gravity?
