What is Critical Power in Cycling?

You've probably heard the term "critical power." Understanding and utilizing critical power (CP) can greatly enhance your performance and help you make significant progress.

Understanding Critical Power in Cycling

Critical power is the highest average power you can sustain for approximately one hour, measured in watts. Cyclists use CP to assess their strengths, identify weaknesses, and set training zones. Similar to FTP (Functional Threshold Power), a higher CP generally indicates a better capacity to maintain power during endurance rides.

CP testing is based on the principle that your power output above a certain threshold follows a power-duration curve, defined by CP and W’ (W prime). W’ represents the total work you can perform above your CP before reaching exhaustion, measured in kilojoules (kJ). Essentially, W’ indicates your ability to sustain efforts beyond your CP.

Critical Power vs. FTP

FTP is another metric used to measure cycling performance. It represents the highest average power you can maintain for about an hour without fatiguing, expressed in watts per kilogram. Cyclists often use FTP to gauge overall fitness and the difficulty of a ride.

While CP and FTP are similar, they are not identical. FTP measures the maximum sustainable power for an hour, whereas CP reflects the capacity of your aerobic system, one of your body’s three energy systems. The aerobic system uses oxygen to burn carbs and fats, providing a slower but sustained energy release, essential for long rides.

FTP can be determined using a 20-minute test, but this method has limitations in accuracy and relevance for some cycling types. Critical power testing, on the other hand, can offer a more comprehensive assessment of your cycling capabilities.

Average Critical Power (CP) Stats for Cyclists

Amateur Cyclists:

• Male: Amateur male cyclists typically have a CP ranging from 3 to 4 watts per kilogram (W/kg). For instance, a 70 kg male cyclist might have a CP between 210 and 280 watts​ 
  

• Female: Female amateur cyclists usually have a slightly lower CP, averaging around 3.5 W/kg. For example, a 60 kg female cyclist might have a CP of approximately 210 watts​ 

Professional Cyclists:

• Male: Professional male cyclists boast significantly higher CP values. For example, Tadej Pogačar has a CP of around 6.42 W/kg, with absolute power often exceeding 400 watts. Egan Bernal, weighing 59 kg, has a CP of 383 watts, which translates to a relative CP of 6.50 W/kg​ 

• Female: Professional female cyclists, such as Evelyn Stevens, can achieve CP values around 5.55 W/kg, with their absolute power figures also being quite high, though typically lower than those of male professionals​ 

CP in Context:

• All-Rounders: These cyclists exhibit balanced power outputs across various durations, excelling in both short, high-intensity efforts and longer, steady efforts. Their CP reflects this versatility​ 

• Climbers: Typically lighter, these cyclists have a high CP relative to their weight, enabling exceptional performance on climbs. High CP is essential for maintaining power over extended periods​ 

• Sprinters and Puncheurs: These cyclists excel in short, explosive efforts. Their CP might be lower over longer durations but very high in short bursts, showcasing their anaerobic power and ability to perform intense efforts repeatedly​ 

These statistics highlight the variation in CP across different levels of cyclists and provide a framework for understanding performance capabilities in various cycling disciplines.

Benefits of Critical Power Testing

Critical power testing provides several advantages for cyclists:

1. Comprehensive Physiological Insight: CP testing offers detailed data on your maximum sustainable power and your capacity above this power.
   

2. Accuracy: CP testing doesn’t rely on as many physiological assumptions as FTP testing, making it potentially more reliable.
   

3. Identification of Strengths and Weaknesses: By giving a fuller picture of your abilities, CP testing is widely accepted across various cycling disciplines, helping you identify areas for improvement.
   

4. Pacing Strategy: Knowing your CP and W’ helps you estimate your power over specific durations, aiding in race and training pacing. Online CP calculators can help you determine the power you can sustain over different periods.
   

Limitations of Critical Power Testing

Like any testing method, CP testing has its downsides:

1. Time-Consuming: CP testing requires two maximal efforts, making it a lengthier process.

2. Variable Performance: Results can be affected by factors like hydration, fatigue, and nutrition.

3. Incomplete Picture: While informative, CP testing doesn’t provide a complete overview of your physiological capabilities, which would require a lab setting.

How to Test for Critical Power

A common method for CP testing involves two maximal efforts:

1. Warm-Up: Start with a 10 to 15-minute warm-up.
   

2. First Test: Ride as hard as you can for 3 minutes, maintaining maximum consistent power.

3. Rest: Cool down and rest for 30 to 40 minutes or until the next day.

4. Second Test: Warm up again and then ride as hard as you can for 12 minutes, maintaining consistent maximum power.

5. Calculation:

• Multiply the average power from the 12-minute test by 12.

• Multiply the average power from the 3-minute test by 3.

• Subtract the second result from the first.

• Divide by 9 to get your CP.
  

Alternatively, online tools can simplify the calculation process.

Using Your Critical Power Results

To track your progress and improve as a cyclist, retest your CP every three months. This will help you gauge your fitness improvements and assess the effectiveness of your training program. Additionally, use your CP results to estimate your training zones, much like with FTP. Consulting a trainer can ensure your training zones are accurately calculated and aligned with your goals.

Conclusion

Critical power is the highest average power you can sustain for about an hour and is a vital metric for cyclists. While similar to FTP, CP offers a broader understanding of your physiology, helping you tailor your training to enhance performance. Regular CP testing can guide your training, allowing you to monitor progress and identify areas for improvement.