What is FTP, and How it Works?
Functional Threshold Power (FTP) represents a cyclist's highest average power for about one hour without significant fatigue. Scientifically, FTP aligns closely with the lactate threshold—the intensity at which lactate accumulates in the blood at a faster rate than it can be cleared. This accumulation leads to muscle fatigue and limits sustained performance. FTP provides a practical way to measure this critical performance threshold, which is particularly valuable in structured indoor cycling environments like Zwift, where precision pacing is crucial.
FTP also reflects metabolic efficiency and muscular endurance. It involves energy pathways—particularly aerobic metabolism—that determine the body's ability to sustain higher intensities without undue fatigue.
Ways Determining Your FTP
Calculating FTP can be done using several established testing methods:
60-Minute Test:
Considered the gold standard, requiring the cyclist to maintain the highest sustainable power for one full hour. FTP equals the average power output.
20-Minute Test:
After warming up, perform an all-out 20-minute ride, then multiply your average power by 0.95. This correction factor compensates for the shorter test duration, providing a close approximation to the 60-minute FTP.
8-Minute Test:
Two separate maximal 8-minute efforts separated by a 10-minute recovery. FTP is estimated by multiplying the average power from these intervals by 0.90.
Ramp Test:
Increase intensity in increments until exhaustion (usually every minute). FTP is estimated by taking 75% of the power sustained during your last fully completed step. Ramp tests are convenient, consistent, and especially popular on Zwift.
Calculating your Watts per Kilogram (W/kg):
Formula: FTP (watts) ÷ Body Weight (kg).
Important for evaluating relative cycling performance, particularly for climbing and virtual racing on Zwift.
Why FTP Doesn’t Fully Define Athlete Fitness
While an essential metric, FTP is influenced by multiple external and internal factors and thus provides only a partial picture of overall fitness:It can be more about DURABILITY that plays a bigger role in an athlete's overall fitness.
Glycogen Availability: Glycogen stores directly impact performance. A well-fueled athlete can sustain higher power levels longer, emphasizing the need for proper nutrition pre-ride.
Hydration and Electrolyte Balance: Even slight dehydration can significantly impact your power output and endurance.
Sleep Quality and Quantity: Adequate rest directly influences your body's hormonal balance, recovery, and muscular readiness.
Psychological Readiness: Stress, motivation, and focus greatly influence performance. Mental fatigue can reduce FTP dramatically, while positive mental states can bolster FTP significantly.
Additional Physiological Factors Influencing FTP
Beyond basic metabolic factors, FTP is influenced by:
Muscle Fiber Composition: Cyclists with a higher proportion of slow-twitch muscle fibers typically have better endurance and higher FTPs, whereas fast-twitch dominant cyclists excel in short, powerful efforts.
VO2 Max: This measures your body's maximal oxygen uptake and influences FTP because it determines your upper aerobic ceiling.
Capillary Density and Mitochondrial Efficiency: More efficient energy production and oxygen transportation directly elevate FTP.
Misconceptions about FTP
Common misunderstandings include:
Higher FTP Means Superior Overall Cyclist: FTP primarily assesses sustained power capability but does not reflect sprinting ability, tactical awareness, bike handling, or overall endurance.
Only Threshold Training Improves FTP: Balanced training, including zones ranging from endurance to VO2 max intervals, is critical to improving FTP sustainably and avoiding plateaus.
FTP Remains Stable: FTP is dynamic, continually responding to training load, recovery quality, nutritional strategies, and overall stress.
6. Common FTP Questions Answered
How Often Should I Test FTP?
To maintain accurate training zones, it is recommended that you exercise regularly, typically every 4–8 weeks or after significant training blocks or disruptions.
Can FTP Decline Temporarily?
Absolutely, due to fatigue, illness, stress, inadequate nutrition, or overtraining.
Should FTP Be My Only Training Metric?
No, FTP should be one of several metrics, including heart rate variability (HRV), perceived exertion (RPE), and training stress scores (TSS).
Is FTP Training Only for Competitive Cyclists?
FTP-based training is beneficial for all cyclists aiming for structured progress, whether recreational or competitive, especially in indoor environments like Zwift.
Maximizing FTP on Zwift: Indoor Cycling Advantages
Zwift provides a controlled environment, making FTP tests consistent and workouts precisely targeted:
Consistency and Precision: Zwift eliminates variables such as traffic, wind, and terrain irregularities, allowing precise control over training intensities.
Motivation and Engagement: Zwift's interactive environment enhances mental engagement, enabling cyclists to maintain motivation and sustain higher intensities during FTP tests and structured training.
Controlled Training Sessions: Erg mode in smart trainers precisely maintains target wattages, ensuring each workout aligns exactly with prescribed FTP zones.
Effective Training Methods to Increase FTP
To sustainably improve FTP:
Sweet Spot Training (88–94% FTP): Highly efficient in boosting FTP by providing substantial stimulus while allowing quicker recovery than pure threshold efforts.
VO2 Max Intervals (106–120% FTP): These intervals increase the aerobic ceiling, allowing higher sustained power over longer durations.
Endurance and Base Training (55–75% FTP) are essential for long-term improvements in aerobic capacity and for enhancing overall metabolic efficiency.
Anaerobic Capacity Workouts: Short, intense intervals to boost muscular power and enhance lactate tolerance.
The Science Behind FTP Improvement
Improving FTP involves enhancing physiological markers such as mitochondrial density, capillary networks, lactate clearance capabilities, and metabolic flexibility. Regular training across various intensities enhances muscle adaptations, improving the body’s ability to sustain higher intensities for prolonged periods. Recent research and insights suggest that durability—the capacity to sustain power output under fatigue conditions—offers a more comprehensive evaluation of a cyclist’s endurance, especially when assessing young and older athletes.
Durability tests more realistically reflect cyclists' conditions in actual competition and training, where fatigue significantly impacts performance. Unlike fresh-state FTP tests, durability assessments measure FTP or sustained efforts after prolonged exertion. For example, an athlete might initially perform an FTP test in a rested state and then repeat the test after several hours of moderate to high-intensity riding. Comparing power output from these tests provides insight into an athlete’s fatigue resistance and ability to maintain high performance despite accumulated fatigue. In his recent video, Dylan Johnson highlights this effectively, emphasizing how durability better indicates real-world cycling endurance and performance (Johnson, 2024).
Such tests can reveal critical differences in fatigue resistance between younger and older cyclists, who might show similar fresh FTP results but differ significantly under fatigue. Consequently, assessing durability can more effectively guide personalized training strategies, enhancing overall performance and recovery management.
Despite the emerging emphasis on durability, accurate FTP measurement remains essential. FTP provides a clear and quantifiable metric for establishing individualized training zones, ensuring workouts match a cyclist’s fitness levels. Thus, combining FTP assessments with durability testing yields the most effective approach, accommodating individual performance characteristics and aging effects.
Durability tests alongside traditional FTP measurements provide a nuanced understanding of a cyclist's true capabilities and performance potential across different age groups. This combined approach enables personalized and effective training interventions, improving cycling performance and long-term athlete development.
References:
Holistic Approach to FTP Training
FTP is a cornerstone of structured cycling training that benefits indoor platforms like Zwift. Recognizing FTP as dynamic and influenced by multiple factors, cyclists should engage in balanced training regimens incorporating various intensity zones and proper recovery. FTP improvements are best supported by holistic strategies, including nutrition, sleep hygiene, hydration, and mental readiness, ensuring sustained performance growth and overall cycling enjoyment.
Citations: BikeRadar. (2023). What is FTP and why does it matter for cyclists? Retrieved from https://www.bikeradar.com/advice/fitness-and-training/what-is-ftp-and-why-it-matters-for-cyclists
High North. (2023). Fatigue resistance & 'durability' in cycling: Tests and training tips. Retrieved from https://www.highnorth.co.uk/articles/fatigue-resistance-durability-cycling
Johnson, D. (2024). This is better than FTP (seriously). [Video]. YouTube. Retrieved from https://www.youtube.com/watch?v=x-eUPB9wzYY
W/KG. (2023). The science of durability: Are you strong where it matters? Retrieved from https://www.wattkg.com/science-of-durability
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