Zwift: (Benefits of) riding on the limits

Why it's important to know your zones

This is a sponsored article in association with Zwift.

When Sir Bradley Wiggins scorched around the Lee Valley Velodrome in London on a sultry Sunday in June 2015, much of the talk centred around Wiggo’s functional threshold power (FTP). This is because this cycling term, born from the labs, describes the maximum number of watts (power) a cyclist can maintain for an hour. The higher your FTP, the more power you can produce, and the faster you can ride.

Understandably, professionals aren’t too willing to share their physiological limiters with the world, but the rise of power meters and online training platforms such as TrainingPeaks mean we now have greater access to these cycling icons than ever before.

Chris Froome’s FTP, for instance, is reportedly 420 watts, while Wiggins described how he generated an average 456 watts for 55 minutes en route to time-trial silver at the 2011 World Championships. As for recreational riders, a superb roadie will be touching 320 watts, while a fair amateur will hover around the 200 watt mark.

If you tip over your FTP, fatigue soon sets in. That’s down to lactic acid, which starts to accumulate in your muscle cells and then spills over into your bloodstream. Despite advances in cycling science and technology, no-one knows the exact mechanism of why that then leads to you slowing down, but it’s clear that it’s a mix of physiological (higher acidity leads to inefficient muscle function) and psychological (your brain perceives this raised acidity as a threat to its homeostasis, so slows your limbs down) factors.

Setup using your iPad
Setup using your iPad

Calculating your FTP

That’s all very well but how do you determine your FTP on Zwift? And once you’ve calculated your FTP, how can it help you improve your cycling? Both good questions with equally pleasing answers.

When it comes to your FTP, Zwift actually gives you three options:

  1. The full 60-minute FTP test
  2. An abbreviated 20-minute FTP test
  3. An estimated FTP based on your performance during non-workout rides

During both the FTP tests, you’ll warm up before riding a challenging effort level for the remainder of the test.

Once you have this golden wattage figure, you can then go about setting your training zones. There are various zonal methods out there, but the one employed by the majority of WorldTour teams is the seven-zone system devised by the American Dr Andrew Coggan, with each zone corresponding to a physiological adaptation.

Here’s an idea of how the seven zones impact your cycling performance:

 Training zonePower outputPhysiological adaptationPerformance benefit
1. Recover<55% of thresholdIncreases bloodflow to flush out waste products and deliver nutrientsBoosts recovery. In turn, lays foundation for harder sessions
2. Base endurance56–75%Stimulates fat metabolism; prepares muscles, tendons, ligaments and nervous system for cycling More efficient use of energy
3. Tempo76–90%Boosts carbohydrate metabolism; changes some slow-twitch muscles to fast-twitchersIncreases sustainable power
4. Threshold91–105%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 power106–120%Builds cardiovascular system and VO2 max Improves time-trialling ability and resistance to short-term fatigue
6. Anaerobic capacity>121%Short, intense efforts of 30secs to 3mins increase anaerobic capacityBuilds the ability to break from the group
7. Neuromuscular powerMaximalRaises maximum muscle power; develops neural control of pedalling at specific cadenceGood for short sprints

Setup using your iPad
Setup using your iPad

Professionals will often print out their individual zones on a piece of card and tape them to their stem, giving them a clear visual of what power output they should maintain depending on the aim of that particular session.

That visibility is made far easier with Zwift, thanks to its on-screen power display that shows you exactly how many watts you need to push during each pre-set interval. This has the effect of ensuring you train smart, instead of going all-out every session and falling down ill.

Plan your zones

You can now begin planning your rides, so if you’re goal is to strengthen your performance to break from a group, a session involving high zone-six work is what you’re after. Because this will be tiring, you’d then pencil in a zone-one recovery session the following day.

The final thing to mention is that as your fitness improves, so does your FTP. So, it’s worth retaking the FTP test once a month or every six weeks, because a change in FTP has an impact on training zones.

Just mimic the conditions of the original FTP test, taking into account things such as having fresh legs, consuming breakfast three hours before and hydrating with at least one bottle of water.

This article was published by BikeRadar, the world's leading source of bike reviews, gear reviews, riding advice and route information
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