How to Perform an Indoor Field Test (in Zwift)

Performing a 20-minute field test indoors can be a highly effective and repeatable method for establishing your wattage training zones and measuring your improvement. Execution of the test indoors requires an attention to details that we'd like to share in this training tip. Because the harder you 'go' the better the test.

Goals: to determine your Power-Based Wattage Training Zones

The purpose of this test is to achieve the highest average power for 20 minutes.

TURN OFF ERG MODE so you can go as hard as you can 🙏

By testing and going as hard you will be able to find out what you are capable of - its more than you think!  Then you will be able to achieve precise physiological adaptations from your various sweet spot, tempo, VO2, threshold and anaerobic intervals this indoor cycling season.

We recommend one of two ways to do an indoor test in zwift:

#1 Send the CoachCat 20 minute Field Test to Zwift and remember to turn off the ERG mode right before the 20 minute portion of the 'workout' - the test begins.

#2 A free ride in Zwift where you choose a climb like the Alpe D'Zwift to simulate climbing conditions.  If you ask CoachCat, CoachCat will recommend the Tempus Fugit course because it is flat and free of undulations:

How to Not Go TOO Hard 

Rule # 1 is to not go too hard in the first 3- 5 minutes. This is called proper pacing. Using your powermeter makes properly pacing your field test a cinch. Most athletes will test in the 200-300 watt range. So starting your test at 400 watts is too hard!

Most often, athletes following a CoachCat training plan will have conducted the all important 2 x 10 min max threshold effort workout 3 days prior to the prescribed field test.  The power output from these two 10 minuters will help you understand what poer you can make for double the length on test day.

You should also 'feel' the effort and use real time wattages as guidelines. For example, “Try going as hard as you feel you can sustain for 20 minutes” without going above 300 watts (for example).

To do the test by feel, start slightly conservatively for the first 5 minutes, then settle into a hard but sustainable effort for the middle 10 minutes, and finally give it everything you’ve got in the final 5 minutes. Remember, no ERG mode—pace by feel. 

Remember, this is a max effort by the end - give it everything you got. If you can barely pedal afterwards - you did it right. 

Additional Considerations:

After proper pacing nutrition, hydration, air flow and M O T I V A T I O N are 4 essentials to performing an indoor field test properly.

• Nutrition & Hydration: Eat a healthy carbohydrate meal 3-4 hours before the test. It is important to have your glycogen stores topped off before attempting this workout! Hydrate well beforehand but once the test begins don't worry about needing to drink although you can sip on mix.
• Air Flow: Use a fan directly on you and ideally test in a room that is 60-68 degrees.
• M O T I V A T I O N: Be motivated for your test! A 20-minute full gas effort is a mentally challenging task. In order to generate the highest wattage you can achieve you will have to bear down and suffer.  If you give it your all and do not quit, then you did the test right. 

After your test, the instant AI analysis in CoachCat will tell you what your 20 minute power was.  If (and only if) you set a higher FTP than what you previously had set in your zones, CoachCat will auto-detect your new higher FTP.

Train hard and consistent over the winter and test one more time before your indoor cycling season ends. "Indoor" power tends to be lower than "outdoor" power so when test a second time make sure it is with the same powermeter under the same conditions (indoors). Take what you learn from your first indoor field test and apply it to your second test. If you've been consistent and raised your training load, most likely you'll be able to measure your improvement in watts. Going from 225 to 250 watts in 12 weeks is a legit 10% improvement. Congrats in advance!

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