How do Stroke Volume and Muscle Wall Thickness Affect Cardiac Output (Science of Getting Faster 1)

TL;DR

Training and heat acclimation can lead to an increase in cardiac output, which improves oxygen delivery and enhances endurance performance.

Transcript

One of the big physiology things that we saw physiological change we saw, we saw change in, in, in maximum cardiac output. That's the only way I can explain that that VO two max went up. Right. And so the question becomes, well, how do you, how is well-trained athletes? How'd you get an increase in, in, uh, cardiac output. Um, and, and just take on... Read More

Key Insights

• 🖐️ Physiological changes, such as increased cardiac output, play a crucial role in improving endurance performance.
• 🔇 Heat acclimation and hydration during training can lead to an increase in plasma volume, which supports the expansion of ventricular chambers and increases stroke volume.
• 🥺 Increased stroke volume allows for more oxygen delivery to working muscles, leading to enhanced aerobic capacity.
• 🏋️ Weight gain from increased plasma volume has minimal impact on performance compared to the benefits of improved cardiac function.
• 💪 Changes in muscle thickness can occur alongside ventricular chamber expansion, further contributing to enhanced cardiac function during exercise.
• 🤩 The increase in cardiac output, rather than changes in red blood cell concentration, is the key factor in improving oxygen delivery and performance.
• ✋ The incremental performance benefits of higher cardiac output outweigh the negligible impact of weight gain in cycling and running events.

Questions & Answers

Q: How do well-trained athletes increase their cardiac output and VO2 max?

Well-trained athletes can increase their cardiac output by increasing their stroke volume through endurance training and heat acclimation. This leads to improved oxygen delivery and enhanced performance.

Q: Can changes in muscle thickness also contribute to improved cardiac function?

Yes, along with the increase in ventricular chamber size, changes in muscle thickness can occur with heat acclimation. This may result in better contractility and further support cardiac function during exercise.

Q: If plasma volume increases, does that mean there are fewer red blood cells and less oxygen carrying capacity?

Although an increase in plasma volume may lead to a reduced concentration of red blood cells, the overall oxygen delivery per minute is increased due to the higher cardiac output. This means more red blood cells are delivered to the muscles, improving oxygen availability.

Q: Does weight gain from increased plasma volume affect performance in cycling and running?

The weight gain from increased plasma volume (approximately half a pound) is negligible and is unlikely to have a significant impact on performance. Higher cardiac output and improved lactic threshold have a greater influence on performance.

Summary & Key Takeaways

• Physiological changes, such as increased maximum cardiac output, can result in improved VO2 max and endurance performance in well-trained athletes.

• Heat acclimation and hydration during training can lead to an increase in plasma volume, which in turn increases stroke volume and cardiac output.

• The increase in cardiac output allows for more oxygen delivery to the working muscles, enhancing aerobic capacity and performance.