Durability: The Quality That Wins the Last Hour

By Ric Stern

Last week’s column discussed how having the same FTP as another rider can lead to a different outcome — where, for example, you could be dropped on a hill mid-ride. But we also touched on another aspect, and this one is incredibly important too: durability.

So what do I mean by durability? It’s simply the ability to ride hard — at or near threshold — after you’ve already accumulated fatigue. It’s a crucial part of training whether you’re preparing for an ultra bike race, the Tour de France, or even a moderately short road race of a couple of hours.

Usually you’d define some sort of fatigue marker first. World Tour riders — those doing the Classics or the Tour de France — might be expected to perform up to 5,000 kJ of work and then see how close they can get to their FTP after that. For us lesser mortals, the amount of work you’d do before your fatigued test would be a good deal less.

Durability is a relatively new concept, at least as a metric for testing. Current research has looked at the differences between World Tour pros (those who ride the Tour) and the rung below (Pro Tour). Across various durations there’s no real difference in power output between the two groups for short-duration efforts, but there was a gap at longer maximal efforts (over 30 minutes). And once pre-fatigued, that gap tended to widen across all durations. The riders at the very top could ride more than 3,000 kJ and still have as little as about a 2% drop in power over a 30-minute TT-type effort.

Fast short, fast long

But how does this shape your training if you’re doing an ultra? Last week I mentioned James Hayden — his durability was excellent, and he was fast at ultras but also fast over short durations. Sub-20-minutes for a 10-mile TT fast (over 30 mph).

Another rider I worked with was Jeff Jones — at the time editor of cyclingnews.com and BikeRadar. Jeff won the British Best All Rounder (BBAR), the competition for the fastest cumulative speeds across 50 miles, 100 miles, and 12 hours. He set a world record for the 12-hour, riding 305 miles — a bonkers-fast 25.4 mph for 12 hours nonstop. He also recorded 10-mile TTs in 19 minutes.

And the research tends to show that those who are fastest over short distances (about 20 minutes) are also fastest over long ones. It’s an important concept to grasp: you don’t just need to train long, you need to train fast as well.

How to test your durability

You’d complete a 20- to 30-minute TT in a fresh state after warming up. Let’s say you average 220W. Then a week or so later, you’d complete a chunk of work first, and at the end of it perform the same test again. Say this time it’s 205W. That’s a drop of around 7% — a solid result — and with training you’d aim to close that gap further between your fresh and fatigued efforts.

How much work should you do beforehand? In some of the research, scientists used 16 kJ per pound of bodyweight (35 kJ per kilogram) — so a 154-pound rider (70 kg) would do 2,450 kJ before the fatigued test. But I’d suggest using these more realistic figures as a guide:

• Recreational riders (under 5 hours a week): durability often drops after 1,000-1,500 kJ
• Trained masters cyclists (6-10 hours a week): many start fading around 1,500-2,000 kJ
• Stronger amateur racers: 2,000-3,000 kJ
• World Tour professionals: capable of decisive efforts after 3,000-5,000 kJ

And what should you be looking for in the drop-off?

• Within about 5% of your fresh effort: your durability is excellent.
• A drop of 5-10%: very common, and still leaves plenty of room to improve.
• A drop of 10-15%: durability is a clear limiter.
• More than that: it’s almost certainly the thing holding you back on long rides and races, not your absolute FTP.

How to train your durability

For masters cyclists, durability improves when several pieces come together.

First, a strong aerobic base. This comes from genuine Zone 2 work, not half-hard riding that drifts into tempo. In my training levels, that means sitting around 50 to 65% of your MAP for sustained periods. This is where you build mitochondria, capillary density, and improved fat oxidation — and where you learn to ride for two to four hours without turning everything into a threshold session.

Second, some MIET. MIET sessions (moderately intensive endurance training — others call it sweet spot), done sensibly, help you hold a reasonably high percentage of threshold for longer, and teach your system to tolerate steady load without blowing up. For most masters riders, one or two a week is plenty.

Third, strength training. Durability isn’t just metabolic; it’s also about neuromuscular resilience. If you lose the ability to produce force late in a ride, your power falls even if your heart and lungs are fine. Strength work for the legs and trunk helps you hold posture, torque, and stability deep into a long day. Put the bike first, though — on days you combine hard cycling and strength, do the quality bike session earlier and lift several hours later. Heavy squats followed by trying to hit big power numbers rarely ends well for a masters rider.

Fourth, fueling. Most riders over 40 under-fuel almost every long ride they do, and that’s one of the fastest ways to destroy durability. If you want to ride strongly after 1,500 to 2,000 kJ, you need to take on carbohydrate early and consistently — around 60 to 90 grams per hour on longer rides for most riders (well-trained guts can handle more). That’s not gluttony; it’s what your muscles and brain need to keep performing.

Fifth, “fatigued-then-hard” sessions, used sparingly. Once you’ve built some base and you’re fueling properly, it can be very effective to accumulate a sensible amount of work and then add intervals at the end. Ride Zone 2 for two to three hours, reach around 1,400 to 1,800 kJ, then complete a small block of threshold or VO2max intervals before calling it a day. These teach your body and brain to produce quality efforts while tired. Every 10 to 14 days is enough for most masters riders.

A simple four-week durability block

Assuming you’re already riding several times a week:

• Week 1: One long Zone 2 ride to around 1,400 kJ. In the last part, add two intervals of eight minutes at MIET, with easy riding between.
• Week 2: Same idea, but extend the long ride to around 1,600 kJ and finish with three intervals of six minutes at 95 to 100% of FTP.
• Week 3: Increase the long ride to about 1,800 kJ and finish with four intervals of three minutes at roughly 105 to 110% of FTP.
• Week 4: A recovery week. Keep rides shorter and easier, with just one light MIET session rather than a long durability ride.

Combine that with one other quality session in the week (another MIET or VO2max session), some easier endurance work, and sensible strength training, and you’ll usually see a noticeable improvement in late-ride power within four to six weeks.

And, as mentioned last week, keep working on your FTP and MAP too — the higher those are, the better your durability is likely to be on top.

Durability is one of the most trainable qualities there is — but it needs structure: the right base, the right amount of intensity, progressive overload, and proper fueling, in the right order. If you’d rather have that built for you around your own numbers and the time you’ve actually got, that’s exactly what MAP: The Build does — a structured four-week block delivered straight into your TrainingPeaks calendar, ready to ride. £25 (about $34) per four weeks. Have a look here →

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Ric Stern is founder of CycleCoach and has coached athletes to World Championship gold, Commonwealth medals, and Paralympic podiums across 29 years.