Cardiovascular Drift
Cardiovascular drift is a fascinating phenomenon that occurs during prolonged exercise, particularly in warm conditions. Let's break down this complex concept into digestible pieces.
What is Cardiovascular Drift?
Cardiovascular drift refers to the gradual changes in cardiovascular function that occur during sustained exercise, typically characterized by:
- A progressive increase in heart rate
- A decrease in stroke volume
- A reduction in cardiac output
- A decrease in arterial blood pressure
These changes typically begin after about 10-15 minutes of continuous exercise and can continue for the duration of the activity.
The Mechanisms Behind Cardiovascular Drift
1. Temperature Effect
- As exercise continues, core body temperature rises
- Blood vessels in the skin dilate (vasodilation) to help cool the body
- More blood is directed to the skin for cooling rather than to working muscles
2. Fluid Loss
- Sweating leads to decreased blood volume (plasma volume)
- Less blood returns to the heart (reduced venous return)
- Results in decreased stroke volume
3. Compensatory Response
- Heart rate increases to try to maintain cardiac output
- Despite increased heart rate, overall cardiac output may still decrease