1. What is Critical Swim Speed?

Critical Swim Speed (CSS) is an estimate of a swimmer's aerobic threshold pace, representing the fastest speed a swimmer can maintain without accumulating lactic acid. It's a useful metric for training intensity prescription in pool swimming.

2. How Does the Calculator Work?

The calculator uses the CSS formula:

Where:

• 400m time — Time taken to swim 400 meters in seconds
• 200m time — Time taken to swim 200 meters in seconds

Explanation: The difference between 400m and 200m times divided by 2 estimates the swimmer's aerobic threshold speed.

3. Importance of CSS Calculation

Details: CSS helps swimmers determine appropriate training intensities, monitor progress, and establish baseline performance metrics for endurance training.

4. Using the Calculator

Tips: Enter both times in seconds (400m time must be greater than 200m time). Use recent, maximal effort time trials for accurate results.

5. Frequently Asked Questions (FAQ)

Q1: Why use 400m and 200m distances?
A: These distances provide a good balance between aerobic and anaerobic contributions, allowing accurate estimation of aerobic threshold.

Q2: What are typical CSS values?
A: Competitive swimmers typically have CSS between 1.0-1.5 m/s, while recreational swimmers may be 0.7-1.0 m/s.

Q3: When should time trials be performed?
A: Perform when well-rested, ideally in the morning with proper warm-up. Avoid testing after hard training sessions.

Q4: Are there limitations to CSS?
A: CSS may underestimate true aerobic threshold in sprinters and overestimate in endurance specialists.

Q5: How often should CSS be retested?
A: Every 6-8 weeks during training cycles to monitor progress and adjust training zones.