Durability is a term that comes up more and more frequently in relation to cycling performance, as it can be used as a performance marker to distinguish the very best from the best. It can also be termed as 'fatigue resistance' as it is determined by a riders ability to resist fatigue and produce high power outputs in a fatigued state, e.g. in the final decisive moments of a race.
During prolonged cycling fatigue is accumulated and with that follows a downward shift in the power a cyclist can produce over a given duration of time. The smaller the decrease in maximal power outputs in a fatigued state compared to maximal power outputs in a fresh state the better the durability of a rider. Thus, the ability to produce power in a fatigued state shows how resistant your body is to accumulated work during a race.
This accumulated work (induced fatigue) can be due to many hours of riding at continuous endurance-tempo pace or a race with several high intensity efforts. The rider with the best durability will most likely win the race, as he or she can dig deeper in the final attack or sprint. In other words a riders durability can be a better predictor of race performance than maximal power numbers produced in a fresh state.
So how do you measure durability? Simplified you have a cyclist to do some hard all out efforts in a fresh state and in a fatigued state, and the you see how much power output is affected by the accumulated fatigue.
The next question is how much work a rider has to do to be in a fatigued state? Approximately 2000 kj of work, which is around 3 hours of riding at lower intensity - moderate endurance training.
It has been shown that world tour riders has better durability than pro tour riders, and experience a smaller decrease in maximal power outputs after a certain amount of work completed. The same picture is seen when you compare elite pro cyclist with U23 cyclists. So, durability seems to improve with the competitive level and the number of competitive seasons a rider has in the backpack - i.e. stacking training and race load from year to year. This seems quite obvious! The higher the level and the more training a rider have put in over time, the more resilient a rider should be to fatigue.
Interestingly a recent scientific study looked into how durability is affected when fatigue is accumulated in different ways. 14 riders from UCI Continental or ProTeam accumulated approximately 2000 kj of work in two different ways:
Riding at an intensity below 70 % of their critical power (CP).
Performing a high-intensity interval protocol consisting of 5x8 minutes at 105-110% of CP with 8 minute recoveries in between.
Beforehand riders had completed a power profile test in a fresh state. The protocol consisted of a 15 second, 3 and 12 minute maximal effort. After the fatiguing protocols mentioned above, riders completed the power profile test once again to see how their maximal power outputs were affected by the 2000 kj of work. Further 1 second peak power was also included as a measure. Riders were given 90 gram of carbohydrate an hour during both protocols, to make sure energy supply were sufficient to maintain energy levels during cycling.
Results showed that there was a significant reduction in 1 and 15 second power output after riders had done the interval protocol compared to continuous riding. Further 3 minute power dropped significantly after the 8 minute intervals compared to a fresh state. No differences were found in relation to 12 minute maximal power. It was concluded that short term high intensity power is more affected than longer duration maximal efforts. Thus, the intensity at which fatigue is generated over time (continuous low-moderate intensity vs. variable high-low intensity), has a big influence on a riders durability.
So, taking this knowledge into a competition perspective clearly demonstrate that it's of major importance to preserve energy and avoid digging to deep during a races. Those riders who play their cards right, and avoid to many high intensity efforts, will have more in reserve for the final crucial efforts, that decides the outcome of a race.
References:
Spragg, James, Peter Leo, Andrea Giorgi, Borja Martinez Gonzalez and Jeroen Swart. 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: 21–9.
Leo, P., J. Spragg, I. Mujika, A. Giorgi, D. Lorang, D. Simon, et al. 2020. “Power Profiling, Workload Characteristics, and Race Performance of U23 and Professional Cyclists During the Multistage Race Tour of the Alps.” International Journal of Sports Physiology Performance: 1–7.
Mateo‐March, Manuel, Pedro L. Valenzuela, Xabier Muriel, Alexis Gandia‐Soriano, Mikel Zabala, Alejandro Lucia, Jesús G. Pallares, and David Barranco‐Gil. 2022. “The Record Power Profile of Male Professional Cyclists: Fatigue Matters.” International Journal of Sports Physiology and Performance 17(6): 926–31.
Maunder, Ed, Stephen Seiler, Mathew J. Mildenhall, Andrew E. Kilding, and Daniel J. Plews. 2021. “The Importance of ‘Durability’ in the Physio-logical Profiling of Endurance Athletes.” Sports Medicine [Internet] 51(8): 1619–28.
Spragg, James, Peter Leo, and Jeroen Swart. 2023. “The Relationship between Physiological Characteristics and Durability in Male Professional Cyclists.” Medicine and Science in Sports Exercise 55(1): 133–40.
van Erp, T., D. Sanders, and R. P. Lamberts. 2021. “Maintaining Power Output with Accumulating Levels of Work Done Is a Key Determi- nant for Success in Professional Cycling.” Medicine & Science in Sports & Exercise 53(9):1903–10.