Durability

Durability, also known as fatigue resistance, measures your ability to sustain high performance as fatigue accumulates. It's not about your best effort. It's about how long you can keep going at a high level, deep into a ride or run.

Most peak power curves only show your absolute best numbers, regardless of when they occurred. But in real-world racing and long endurance sessions, what matters more is:

• Can you sprint after 3 hours of riding?

• Can you hold tempo after a hard climb at hour 4?

• Does your threshold drop after 2,000 kJ of work?

This is where durability comes in. It highlights how fatigue affects your ability to perform.

Vekta tracks your peak power outputs (1s, 5s, 1min, 5min, 20min, etc.), not just overall, but also after a given amount of work done, using a kJ/kg threshold.

For every session, you’ll see peaks calculated:

• From 0 kJ/kg (fresh)

• After 10, 20, 30, 40, 50 kJ/kg of work

• (e.g., for a 70kg athlete, 50 kJ/kg = 3,500 kJ of work — a heavy session)

This gives you a visual of how your peak outputs shift as fatigue builds.

Think of it as a power curve — sliced by fatigue level.

• Small drop-offs between early and late peaks → High durability

• Steep declines after 30–50 kJ/kg → Low fatigue resistance

You can analyze:

• Sprint power after long endurance

• VO2max repeatability deep into sessions

• Threshold power after tempo blocks

Durability improves with smart training strategies designed to build fatigue resistance, such as:

• Long sessions with intensity placed late (reverse periodization)

• Back-to-back long days to create cumulative fatigue

• Race simulations with surges and efforts deep into the session

• Optimized fueling and hydration strategies to delay fatigue onset

Peak power tells you what you’re capable of.
Durability tells you when you’re capable of it.

By layering kJ/kg-based peaks into every session analysis, Vekta gives you a true picture of performance under fatigue, helping athletes build not just power, but power that lasts.

• Spragg, J., Leo, P., & Swart, J. (2023). The Relationship between Physiological Characteristics and Durability in Male Professional Cyclists. Medicine and science in sports and exercise, 55(1), 133–140. https://doi.org/10.1249/MSS.0000000000003024

• Spragg, J., Leo, P., Giorgi, A., & Martinez Gonzalez, B. (2024). The intensity rather than the quantity of prior work determines the subsequent downward shift in the power-duration relationship in professional cyclists. European Journal of Sport Science, 24. https://doi.org/10.1002/ejsc.12077