Cycling durability: what it is and how to train it

Last reviewed 28 October 2026

What durability means

Lab tests like FTP, VO2max and lactate thresholds are measured fresh. In a long event you are never fresh. Sports scientists have started calling the resistance to that decline durability: the time course and size of the deterioration in physiological characteristics during prolonged exercise. The term was popularised by Maunder and colleagues in a 2021 Sports Medicine paper arguing that it should be profiled alongside the classic markers.

For a rider, durability shows up as a simple question: if your FTP is 250 W, what can you hold for 20 minutes after four hours and 3,000 kJ of work? A durable rider might manage 240 W. Another rider with the same FTP might manage 205 W. Over a 400 km brevet, that gap decides who rides the night comfortably and who is grinding.

Why it matters more than FTP for ultras

At brevet and ultra-race pace you ride well below threshold, often 60 to 70% of FTP. You rarely need your fresh ceiling. What you need is for the effort you are holding to stay sustainable: heart rate not drifting up, legs still able to push over the next climb, and enough glycogen left to respond to a headwind.

FTP still matters, because a higher ceiling makes your ultra pace a smaller fraction of it. But once your FTP is reasonable, extra durability usually buys more time in a long event than a few more watts at threshold.

How to measure durability

Three practical measures, from simplest to most specific:

• Durability test. Ride two hours in Zone 2 (about 65 to 70% of FTP) while fueling as you would in an event, then do a 20-minute all-out effort. Divide the 20-minute power by your fresh 20-minute power. MeepMeep's Durability Test does exactly this and reports the ratio.
• Fatigued power. Your best 5- and 20-minute power after 1,000, 2,000, 3,000 and 4,000 kJ of work. MeepMeep calculates this from every ride you record or import, indoors or out, so you can watch it change over a season.
• Pw:HR decoupling. On a steady ride, compare the power-to-heart-rate ratio in the first half with the second. Less than about 5% drift on a long Zone 2 ride is a common sign of a solid aerobic base. It only means something on steady rides, which is why MeepMeep shows it only for those.

Retest every 6 to 8 weeks under the same conditions: same time of day, same fueling, similar fatigue going in.

How to train durability

Durability responds to the same things that build endurance in general, with one twist: you have to practise producing power when you are already tired.

• Volume in Zone 2. Long, steady rides are the foundation. They build mitochondrial density and fat oxidation, and they spare glycogen for later in the ride.
• Efforts after a pre-load. Put sweet spot, tempo or threshold blocks at the end of a long ride instead of at the start. A typical progression: 1 hour of Zone 2 then 2 × 10 minutes of sweet spot; later, 3 hours then 2 × 30 minutes of tempo; then 3.5 hours then 3 × 15 minutes of sweet spot.
• Back-to-back days. Two long rides on consecutive days rehearse day two of a 600 km or 1200 km event.
• Fuel the pre-load. Eat 60 to 90 g of carbohydrate an hour during the pre-load. The goal is to train muscular fatigue resistance, not to ride on an empty tank.
• Strength. Low-cadence torque work on the bike, and strength training off it, help the legs keep producing force late in a ride.

Keep the hard sessions to two a week and protect the long ride. Durability is built by repeating good long days, not by a single heroic one.

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