Bike Zones
How intensity is measured in cycling
1. Power
This is the first and best way because this is a direct measure of output and is actually what is produced to move yourself and the bike forward.
Power is measured in watts.
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Advantages:
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Feedback is instantaneous. You instantly get your current power output to your bike computer or multisport watch. It does not lag like heart rate.
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It's a direct measure of output. It's completely objective unlike heart rate that is affected by a whole host of different variables.
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Disadvantage:
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Power meters are expensive.
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2. Heart rate
Heart rate is very valuable in the absence of a power meter.
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Disadvantages:
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It lags. It takes about 3 minutes until the heart rate stabilizes.
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It may not stabilize at all if the intensity is high enough and intervals short enough. This means you can't judge whether your effort was at the right level solely by heart rate for these types of workouts.
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External factors that affect heart rate:
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Caffeine, hydration, weather, temperature, recovery status, etc.
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High intensity workouts with short intervals like VO2max workouts are quite impossible to do based on heart rate.
3. RPE - Rate of Perceived Exertion
In many cases, this is actually better than heart rate. At least if you have some experience in endurance training. Measured using a 10 point scale. 1 as being super easy.
You can check out this RPE scale which has cues to know your exact level of RPE.
Determining zones is based on power at functional (or lactate/anaerobic) threshold
Lactate threshold is equivalent to anaerobic threshold.​ THese can be determined in laboratory testing. For most, this threshold is determined using a field test rather than a laboratory test due to the logistics and costs involved. We call this functional threshold.
Power at functional threshold is your FTP or functional threshold power. This is the most important physiological determinant of endurance cycling performance, because it integrates VO2max and the percentage of VO2max that can be sustained for a given duration.
How to determine functional threshold power (FTP)
​This is where all the training zones are based on - the percentage points of this FTP. and it is determined in a field test, of which there are a few methods.​
My favourite during the winter season is the TrainerRoad 20-minute FTP test.
When riding outside, you can do the following, although chose a place where you can ride hard continuously and safely without stopping for 20mins.
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Warm-up: 10 minutes easy.
Then 3 sets of 1 minute hard and 1 minute easy, 6 minutes in total.
Then 5 minutes easy, 5 minutes hard based on effort.
Then 5 minutes easy again.
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FTP-test: 20 minutes all out time trial. But pace well!
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Cool-down: 10-20 minutes easy spinning
Determine lactate threshold heart rate and FTP by taking the 95% of the average heart rate and the average power for that 20 minutes segment (multiply by 0.95).
FTP is the power that you can sustain in a race for 1 hour.
Training zones in cycling
The zones listed below are based on Dr. Andrew Coggan’s​ Power Training Zones for Cycling, with some adjustments based on recommendations from Scientific Triathlon.
Zone 1 - Active recovery
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Less than 55% of the FTP or 68% of the functional threshold heart rate.​
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A slight difference with my values from that of Dr. Coggan’s, we use 75% of the functional threshold heart rate because often athletes can never hit the 68% even if they go below 55% FTP.
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So for an athlete that has an FTP of 247 and FTHR of 162, it would mean lower than 138 watts and 116 bpm.
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These are the cooldowns, rest between intervals, early parts of warm-ups and also some active recovery rides.
Zone 2 - Aerobic riding/endurance
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Below 75% of FTP or 83% of functional threshold heart rate in Coggan’s zones and 85% of FTHR in Eriksson’s zones.​
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For the athlete that has an FTP of 247, it means staying between 138-187 watts in terms of power. And staying between 116-142 bpm in terms of heart rate.
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Used for long, steady, aerobic, basic bread and butter workouts where you don’t go hard and get volume in.
Zone 3 - Tempo
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This is around the aerobic threshold, still clearly below the anaerobic threshold or FTP.​
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It is 76-90% FTP in Coggan’s Zones.
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An alternative zone in TrainerRoad - 76-84% FTP. They also have a high Zone 3 - Sweet Spot - that Coggan does not have. This is a zone that I like a lot because you can get a lot of benefits like improving your FTP while staying below FTP. This is 85-95% FTP.
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In terms of heart rate, 94% or below of functional threshold heart rate.
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So for the athlete with 247 watts FTP, you have 187-224 watts in Coggan’s zones with 142-161 bpm for FTHR.
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These are your longer tempo intervals like doing 3x12 or 3x15 or 4x15 minutes with 5 minute rest intervals.
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Zone 3 also has a lot of race specific workouts, especially if racing half distance, full distance or olympic distance triathlon.
Zone 4 - Threshold
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Coggan defines this as 90-105% FTP.
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For TrainerRoad, this is 96-105% FTP
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Heart rate would be 95-105% of functional threshold heart rate.
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For me, I end the heart rate range at 102% because when you go beyond that, I have seen that in terms of power you go into Zone 5.
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So for the athlete with 247 watts FTP, you will have 240-261 watts for Z4.
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The kind of workouts done in Zone 4 are threshold intervals. These can be 6-10 minute intervals, or even 15 minute intervals for high end athletes. These are really hard workouts but it works incredibly well to increase your FTP. The rest of the intervals are still relatively short. For example, 4x8 minutes with 4 minute rest intervals which is a very good Zone 4 workout.
Zone 5 - VO2max / maximum aerobic capacity
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​105-120% FTP or beyond 106% of functional threshold heart rate.
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Usually this will be most beneficial when you get to 115% to 120% of FTP.
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110% will not do as much good as 115 or 120%.
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This is where exact prescriptions is getting very important.
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The workouts in this zone are short intervals with very high intensity. A bread and butter example would be 6x3 minutes at 120% of FTP followed by 3 minutes recovery. Rest intervals are similar to interval length generally.
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So for the athlete with 247 watts FTP, you would have 288 watts as 120% of FTP.
Zone 6 - Max effort / anaerobic capacity
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Coggan even has a Zone 7 which is neuromuscular power. But I would combine this with Zone 5 which is more appropriate for triathletes compared to track cyclists.​
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An example workout would be doing 30 second all out reps followed by 5 minutes recovery and repeating this for a few times.
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Examples
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For 4 days per week: a Zone 1 or 2 long ride, then a Zone 4 or 5 quality, then probably a sweet spot workout, then an active recovery (zone 1 or two) or aerobic endurance shorter workout, as short as 30-45 minutes up to 1 hour. Then the quality workouts would be an hour or an hour and 15 minutes.
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Over-unders or criss-cross workouts. There are a few different ways to do them
Just staying within Zone 4, alternating going just a bit below or above the FTP. For example criss-cross so you go for a minute above FTP at 105% FT, and then 2 minutes at 95% and repeat for a couple of times, then rest at a lower intensity, then do it all over again for a few times.
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A continuous Zone 3 to Zone 4 workout, or the other way around. You can do 5 minutes at your FTP, then 5 minutes at high Zone 3, then go back at your FTP for 5 minutes then back to high Zone 3. High Zone 3 will be your recovery intervals.