Zone 2 Training for Cycling: How to Improve Your Aerobic Endurance

Slow down to speed up – here’s our guide to zone 2 training for cycling.

If you want to ride further and faster with less effort, you might need to slow down.

Lower intensity training should be a staple in your weekly log of miles. Perform at a low-moderate intensity to stimulate aerobic development and build aerobic endurance.

Typically, zone 2 training is used to build the “base.”

This type of training consists of long and steady rides, anywhere from 1 to 3, or even 4 plus hours.

It’s also the same intensity you should be riding your long, steady endurance rides (usually on the weekends but these can be any day of the week).

Base training is not only good for preventing injury, but it allows you to build up a solid base of miles to facilitate aerobic development.

If you’re training on Zwift with a smart trainer or using a power meter or heart rate monitor, zone 2 training is performed at 55-70% of your FTP or 60-70% of your max heart rate.

But where do you begin training in zone 2 cycling? This blog will highlight the benefits of training in zone 2, why it’s important, how to actually do it (with a video walkthrough), and we’ll also answer various questions you may have about base and aerobic training.

Zone 2 training benefits

The benefits of zone 2 training are numerous, but the most notable benefits include:

Improved cardiovascular function
Increased number of myoglobin and mitochondria in the cells
Musculoskeletal adaptations

Improved cardiovascular function

Training at low-moderate intensities, including zone 2, improves the size and strength of the heart, mainly the left ventricle.

The left ventricle sends oxygenated blood to your muscles during exercise [6] – the stronger it is, the more efficient it becomes at supplying your body with oxygen when it needs it most – this could be during a long ride, or when climbing your local hill that many residents wouldn’t dare walk, nevermind ride.

But that’s not the only benefit of aerobic training. Spending time in zone 2 also increases your lung capacity – this is how much air you can breathe in from one maximal inspiration (one breath) [1].

The greater your lung capacity, the more oxygen you can breathe to provide your muscles to keep working at the same (or a higher) intensity.

Capillary density is also increased (this allows you to remove waste products faster) and promotes fat burning.

Increased number of myoglobin and mitochondria in the cells

Low-intensity training performed over a long period facilitates aerobic adaptations [5].

Training in zone 2 allows you to stimulate the production of mitochondria – the powerhouse of the cell. The more mitochondria you have, the more energy your cells can access, allowing you to ride further and faster without becoming as tired [4].

Myoglobin production is also increased – this is a protein that transports oxygen to the mitochondria.

Increasing your myoglobin stores provides the mitochondria more oxygen to create more energy – it goes full circle.

Musculoskeletal adaptations

Zone 2 training for cyclists also encourages musculoskeletal adaptations.

Aerobic training stimulates muscle hypertrophy (growth) and also increases slow-twitch type 1 muscle fibers [2]. Slow-twitch type 1 fibers use energy slowly over long periods (such as a long endurance ride) whereas fast-twitch type 2 fibers use up energy very quickly, such as a short intense sprint.

Type 1 fibers possess greater mitochondrial density, muscle glycogen, and contain a high concentration of myoglobin and oxidative enzyme capacity – this translates to a high volume of fuel and fat for those long days in the saddle, whether a training ride or sportive event [7].

Top tip: cycle at lower cadences to further engage and build up the essential cycling muscles.

Why is zone 2 training for cycling important?

Why do we recommend spending a large percentage of your training in zone 2? Why not zone 1 or 3?

Training in zone 1 (less than 55% of your FTP and between 50-60% of your max heart rate) is light intensity. It’s often only used for recovery rides after a hard training session, or sometimes used for longer sportive events.

Zone 1 can also be used as a warm up before entering other training zones as a cool down after a ride.

The problem with zone 1 is the lack of stress on the aerobic system – it doesn’t allow us to stimulate and achieve the cardiovascular and musculoskeletal adaptations we’re after.

So, what about zone 3?

Zone 3 is high intensity (approx 70 to 85% of your FTP or 70-80% of your max heart rate).

The issue with zone 3 training is that although it’s still somewhat aerobic, it also triggers the lactate system and begins to build up lactic acid. This causes chemical changes at the muscular level (shuts off the mitochondria), and causes more fatigue with fewer aerobic fitness adaptations.

Many cyclists find themselves in zone 3 by accident when they should be in zone 2.

But zone 3 can be a great tool for those just starting their journey with interval training – it can be great for developing the upper end aerobic capacity (after you have mastered zone 2).

Zone 2 is difficult enough to stimulate aerobic benefits without the added fatigue of harder training, such as dipping in and out of zone 3 – that’s why it’s so popular.

How to do zone 2 training

Now that you know the benefits, you may be eager to hop on the bike and get going. But before you clip in, you may want to read this next part.

Many cyclists train wrong (that is if they’re looking to improve) – they pedal hard on the flats and burn themselves out on the hills, resting on the downhills without pedalling. And while this method of training may seem productive, it’s quite the opposite.

You’re stressing all and no systems at the same time – entering higher lactate zones, introducing long rest periods, and throwing in some easier pedalling into the mix for whatever reason.

This type of training will make you feel sluggish; perhaps fatigued, and may contribute to overtraining with an increased risk of injury.

Before we get into the specifics, it’s important to talk about maintaining constant pressure on the cranks.

Instead of riding hard out of the saddle up hills and cruising downhill without pedalling, you should be putting out similar power throughout your entire ride. That means pedalling downhill and uphill at the same power. Otherwise, you’re dipping in and out of zone 2 (and other zones).

This is a much more effective way to train.

Maintain constant pressure on the cranks, whether training to heart rate or FTP to successfully build your aerobic base.

How does zone 2 training actually work?

Speed is not an accurate indicator of exercise intensity in cycling [2]. Instead, you need to calculate your zones, either based on heart rate or functional threshold power (FTP).

To calculate these scores, we recommend performing an FTP test. If using heart rate, you can also use the age-old equation: 220 minus your age = your maximum heart rate.

Although keep in mind this doesn’t work for the entire population. It’s rough at best, and sometimes way off the mark for those with naturally higher or lower operating heart rates.

Anyways. now that you’ve got your base numbers, you need an effort indicator to train towards:

Zone 2 training should be performed at 55% to 70% of your FTP or 60-70% of your maximum heart rate.

If you have an FTP of 220, your zone 2 effort would be between 120 and 154 watts.

If training by heart rate, and let’s say you’re aged 30, then your max heart rate would be 190 (remember there is some variation). Your zone 2 training zones would be between 114 and 133 BPM.

Note: if training by power, your trainer may be 10 watts lower than outside (this is the case with many smart trainers).

How to approach your first zone 2 training ride

If you’re riding a few easy rides a week, then you’re halfway there to properly riding in zone 2.

But the key is to maintain a constant effort on the bike, whether a set number of watts or an average heart rate.

We’ve got a great video on how to do base training, featuring a follow-along ride with Cam, showing you how to approach your first zone 2 training ride.

How to Do Base Training (The Three Step Guide)

How to implement zone 2 training into your cycling

If you’re sold on the idea of building strong aerobic base fitness for a set period of time (this allows you to receive the maximum benefits), then we would recommend dedicating at least 4-8 weeks to zone 2 training.

Spend 60-80% of your training time each week in zone 2. If you ride 5 times a week, then three to four of these rides should be at this intensity.

Start with 1-2 hour zone 2 rides and slowly build volume over the following weeks. On the weekends, if you can go long, you can also work towards a 4-5 hour ride over an 8 week period.

Once you’ve developed a good aerobic base fitness level (you’ll know from how physically fit you feel training at zone 2 and based on your fatigue post ride), you can begin the transition to more intensive training.

Whatever that intense training looks like though, keep in mind that you must maintain the aerobic base that you’ve spent the last 4 to 8 weeks building.

If you’re training 5 times a week, dedicate at least one ride, ideally two, to zone 2 training. Otherwise, you’ll begin to lose those training benefits you’ve worked so hard for.

Become a better cyclist with a Road Cycling Academy membership

If you want to become a better cyclist, then consider the RCA Road Cycling Course.

Packed full of training advice (just like this), walkthrough videos, further training advice from experts, and more, the RCA will help you become a stronger and faster cyclist.

Apply For Membership.

FAQs

How many times a week should you do zone 2 training?

Aim for approximately 80% of your training to be zone 2, with the remaining 20% focusing on harder efforts.

How long should I train in zone 2 cycling?

If you’re training for an event, aim to build up to 125% distance for your cycling zone 2 training. For example, if it’s a 50 km race, aim to train upwards of 62.5 km in zone 2.

Can I improve my cycling in zone 2?

Yes! The aerobic training zone (zone 2) is great for improving aerobic endurance, increasing lung capacity, heart size and function, and stimulating the production of mitochondria in the cells.

References

Delgado, B.J. and Bajaj, T., 2019. Physiology, lung capacity.
Farrell, C. and Turgeon, D.R., 2021. Normal Versus Chronic Adaptations To Aerobic Exercise. In StatPearls [Internet]. StatPearls Publishing.
Jeukendrup, A. and Diemen, A.V., 1998. Heart rate monitoring during training and competition in cyclists. Journal of sports sciences, 16(sup1), pp.91-99.
Kamga, C., Krishnamurthy, S. and Shiva, S., 2012. Myoglobin and mitochondria: a relationship bound by oxygen and nitric oxide. Nitric Oxide, 26(4), pp.251-258.
Laursen, P.B., 2010. Training for intense exercise performance: high‐intensity or high‐volume training?. Scandinavian journal of medicine & science in sports, 20, pp.1-10.
Mahdiabadi, J., Gaeini, A.A., Kazemi, T. and Mahdiabadi, M.A., 2013. The effect of aerobic continuous and interval training on left ventricular structure and function in male non-athletes. Biology of sport, 30(3), pp.207-211.
Zierath, J.R. and Hawley, J.A., 2004. Skeletal muscle fiber type: influence on contractile and metabolic properties. PLoS biology, 2(10), p.348.