How to build cycling endurance

The need to know on how to get fitter for longer rides

The question: how do you build cycling endurance? The answer? How long have you got? “Not too long as I want to get out on my bike,” you reply? Okay, we’ll keep things as brief as possible but hopefully deliver the essentials to explain how you can build the endurance required to face a sportive, Sunday morning ride or a gravel sojourn. But first, physiologically what exactly does ‘building endurance’ mean?

Again, this could stretch into tomorrow but one of the big endurance wins is boosting aerobic capacity. The technical name for this is VO2max. Over the years, this has become a byword for fitness with Tadej Pogačar’s reported at 89.4ml/min/kg, Egan Bernal’s around 89ml/min/kg and, the highest of them all, retired cyclist Oskar Svendsen’s 96.7ml/min/kg. We’ll stop right there to explain those metrics, which means the maximum millilitres of oxygen the body can utilise each minute per kilogramme of bodyweight. Broadly, the higher your VO2max, the more oxygen you can use to burn for fuel to power your working muscles, the longer you can ride without bonking. It's tricky to be too direct in comparison with recreational riders because VO2max is affected by age, gender, sporting history… but a good VO2max score for many would be over 50ml/min/kg. 

To increase your aerobic capacity requires numerous physiological adaptations that make you a pair of bellows on a bike. These include: your heart functions more efficiently, pumping out more blood with every beat; your lungs become more efficient, allowing for larger amounts of air to be inhaled and exhaled with every breath as well as improving oxygen uptake; and your mitochondria increase in number and become more efficient. As a reminder, mitochondria are the powerhouses of your cells and where energy is generated.

Top riders like Tadej Pogačar have exceptional VO2max levels (Getty Images)

As a sidenote, many at the top level question VO2max as the panacea of endurance as, quite rightly, there are numerous other factors that come into play in delivering world-class performance, like anaerobic threshold, tactical nous and mindset. But, as sports scientist and founder of performance system INSCYD, Sebastian Weber, says, It never hurts to have a higher VO2max, meaning you can produce more power aerobically. The rate of oxygen uptake is proportional to aerobic energy production with around one watt requiring around 12 ml/min of VO2! At the professional level, it needs to be high if you want to be a great climber, a fast time-trial rider or powerful rouleur, but it’s also important for a recreational rider who’s looking to ride longer, stronger and, ultimately, faster.”

Read more: What is FTP and how do I use it?

Importance of intensity

To stimulate these aerobic physiological adaptations requires riding at the correct intensity. Too low and while it’s fine for recovery and flushing out toxins from a previous, more demanding session, it won’t stress your body enough to grow. Too high and while you will boost aerobic capacity, you’ll also veer into the anaerobic side and potentially maximise neither. An ‘endurance session’ at too high an intensity also tires you out for a subsequent ride that should have been more focused on speed.

Riding by heart rate

So, what’s the ideal intensity? Well, if you’re using a heart rate monitor, you’re looking at around zone two on a five-zone system.

Heart rate is a useful way of gauging your intensity (Getty Images)

Below are the five zones based on finding your lactate threshold. You can find yours by undertaking a 30min time trial where, after a brief warm-up, you ride as far as you can in 30mins. Your average heart rate during the last 10mins is your lactate threshold. You’ll note that these zones aren’t contiguous. That’s due to a buffer between low and moderate and moderate and high. Avoid these ideally as that’s the physiological no-man’s land. 

1. Low aerobic, 75-80% of lactate threshold

2. Moderate aerobic, 81-89% of lactate threshold

3. Threshold, 96-100% of lactate threshold

4. VO2max, 102-105% of lactate threshold

5. Speed, 106%-plus of lactate threshold

Riding by power

If you’re using a power meter, you’re also attuned to training by zones. American coaches Hunter Allen and Andrew Coggan developed this seven-zone method of training to maximise riding time. To boost endurance requires long efforts in zone two…





1 Recover

< 55% of threshold

Increases bloodflow to flush out waste products and
deliver nutrients

Boosts recovery. This lays the foundation for harder sessions

2 Base endurance


Stimulates fat metabolism; prepares muscles, tendons, ligaments and nervous system
for cycling

More efficient use
of energy

3 Tempo


Boost carbohydrate metabolism; helps to develop fast-twitcher muscle fibres

Increase sustainable power

4 Threshold


Further boosts ability to metabolise carbohydrate; develops lactate threshold

Improves sustainable race pace, though too much time in this zone can cause staleness and fatigue

5 Maximal aerobic power


Builds cardiovascular system and VO2max

Improves time trialling ability and resistance to short-term fatigue

6 Anaerobic capacity


Short, intense efforts of 30secs to 3mins increase anaerobic capacity

Builds the ability to break away from your competition

7 Neuromuscular power


Raise maximum muscle power; develops neural control of pedalling at specific cadence

Good for short sprints

In short, to stimulate aerobic adaptations requires low-to-medium-intensity rides that consume as much time as you can afford. Why the longevity, which can stretch to five or six hours for some top-end recreational riders but really is fine whatever you can afford, is not only down to stimulating the physiological adaptations mentioned previously but for two further reasons: boosting the well-known fat-burning and boosting the less well-known interleukin-6.

Burning fat for fuel

When it comes to burning fuel for energy, fat is far more favourable than carbohydrate because of availability. You see, while it’s generally accepted that even the fittest cyclist can only store around 500g glycogen (2,000kcals) – how glucose is stored in the body – even the fittest cyclist has access to tens of thousands of fat calories to furnace more energy. (Just one pound of fat contains a whopping 3,500kcals.)

The problem is, the harder you work, the more your body relies on the less-prevalent carbohydrate (glycogen and glucose) over fats because it’s a more rapid system in keeping those working muscles working. This brings into focus the tipping point from one to the other, which is called the ‘Fatmax zone’. This is the intensity at which the percentage of energy coming from fat is at its peak. Recent research suggests this is around 60% maximum heart rate for the unfit and around 70-75% for the fit. The higher this is, the harder you can work when using fat as the fuel. Again, this is down to those mitochondria, that through training swell in size, meaning they can burn greater amounts of fat with oxygen, so making you a more efficient cyclist. In fact, further studies suggest that fat usage may be 80% higher in athletes compared to sedentary individuals.

So, long rides at moderate intensity will help boost yours, especially if you’re new to cycling. If you’re experienced, you can play around with glycogen-depleted sessions, where you might ride for 90 minutes before breakfast so you’re in a fasted state. But do these at a low to moderate intensity so you don’t place too heavy a demand on your immune system.

Become more fatigue resistant

So, you’ve boosted fat. Now it’s time to see what we’re banging on about with these interleukin-6 levels, or IL-6. This is a cell-signalling compound that studies have shown is released by the muscle in large quantities at low intensity and long duration. IL-6 contributes to fatigue with well-trained endurance athletes producing less of it, which means they’re more fatigue resistant. 

The idea is that exposure to large amounts of IL-6 during cycling is the primary trigger of physiological adaptations that reduce IL-6 during future ride and elevate endurance, with the primary trigger again identified as glycogen depletion. Long, slow rides cause much higher levels of glycogen depletion – and subsequently IL-6 release – than short, fast rides. A hard ride lasting 16 minutes may increase IL-6 levels twofold. A one-hour ride will increase them tenfold.

Long rides at moderate intensity will help boost your endurance (James Startt)

Ultimately, the body can also cope with high levels of low training, slowly adapting along the way, whereas too many high-intensity sessions are so stressful they suppress the parasympathetic system and result in chronic fatigue. 

Which brings us onto the sign-off from legendary endurance coach Joe Friel, who states that to boost endurance and performance requires doing the “least amount”, planning “continual improvement” and being “specific”…

  • “Least amount implies that less is better. How can that be? Most successful athletes support the notion that small fitness gains made over a long time are better than quick fitness changes over a short time. We all know that ‘too much, too soon’ leads to breakdown yet we keep doing it.”
  • “Continual improvement has to do with taking a long-term approach to training. Gradual workout changes from week to week produce fitness that stays with you longer and ultimately reaches a higher level than when big changes are made. Your body is prepared to handle changes of a bit more than 10%. Doing more than what you’re physically capable of absorbing is worse than wasting effort, as it leads to breakdown.”
  • “Most specific has to do with how daily workouts benefit cycling-specific fitness, which is the ultimate goal of training. Each and every workout should have a purpose, whether to improve fitness, maintain fitness or recover. Getting the balance right of these three is key to success.”

To that end, if you can only cycle three times a week, the best way to boost endurance and all-round performance is for a long ride at the weekend where you have more time, a light recovery effort a day or two after and a harder, shorter session the day after. For many, this might be a Zwift effort. If you can increase your long ride by 10% each week, that’s the ideal, but give yourself a mental and physical rest by having a recovery week every four weeks. So your long ride could be 60mins in week one, 66mins in week two, 73mins in week three and then back to 60mins in week four. You then start week five at 10% more than 73mins and so on.

These are the fundamentals of boosting endurance. Key is that you don’t go too hard, too often, unless you’re a hardened campaigner who knows their limits. But boosting endurance is just that. When it comes to cranking up power and speed, that’s a different proposition entirely. For now, go long and slow to moderate.

Cover image by James Startt

Shop now