Analyzing Cardiac Output, Stroke Volume, and Heart Rate Across Populations
Understanding the Key Metrics
Let's break down how cardiac output (CO), stroke volume (SV), and heart rate (HR) vary between different populations and during exercise. Remember, these three metrics are related by the formula:
CO = (HR x SV)
Resting Values Across Populations
Untrained Individuals
- Resting Heart Rate: 60-80 beats per minute (bpm)
- Resting Stroke Volume: 70-80 mL/beat
- Resting Cardiac Output: ~5 L/min
Endurance Athletes
- Resting Heart Rate: 40-60 bpm
- Resting Stroke Volume: 90-110 mL/beat
- Resting Cardiac Output: ~5-6 L/min
Despite having a lower resting heart rate, athletes maintain similar cardiac output due to their higher stroke volume.
Exercise Response Patterns
Untrained Individuals
During exercise:
- HR increases linearly with intensity up to ~200 bpm
- SV increases until ~40-50% of max intensity, then plateaus
- CO can reach 20-25 L/min at maximal effort
Endurance Athletes
During exercise:
- HR increases linearly but maxes out at lower values (~180-190 bpm)
- SV continues to increase throughout exercise intensity
- CO can reach 30-40 L/min at maximal effort
When analyzing data, look for the SV plateau point - it's a key indicator of training status!
