It was over 3.5 years ago when we launched the Tiny Races – innovative events designed to give you a solid VO2 max workout across 4 back-to-back races. They were an instant hit, and we fine-tuned the setup by modifying category setups, disqualifying “snipers” who didn’t race all 4 events, and using a variety of courses.
But over time, we realized that Tiny Races weren’t actually delivering a very “pure” VO2 max workout. Instead, most riders ride below VO2 max for the first several minutes, followed by a sprint finish.
A good workout, to be sure, when repeated 4x. But could we do better? Could we structure races so riders can accomplish a true VO2 max training effort, with extra motivation from the race environment?
The Big Idea: A True VO2 Max Workout Disguised as a Race
Garmin says, “Improvements in VO2 max typically arrive in the form of increased stroke volume (the amount of blood pumped with each heartbeat), increases in blood supply, and adaptations in your muscles at a cellular level that help you store and transfer energy more efficiently.”
But how do you improve your VO2 max?
The simplest traditional VO2 max workout looks something like this: 3-5 intervals at 110-120% of FTP, each 3-5 minutes long, and each followed by an easy rest of the same length as the interval. Something like the “15.9” workout in Zwift – a straightforward VO2 max session, named for the atomic mass of Oxygen:

So a rider with a 300W FTP might do these intervals for a V02 max session:
- 345W (115% of FTP) for 5 minutes
- 5-minute rest (50% of FTP)
- Repeat above 5x
I’ve structured the VO2sday Micro Races to replicate this traditional VO2 max workout in a motivating race setting, complete with a time-based GC.
Structured Workout Racing
The VO2sday Micro Races are nothing like your typical Zwift scratch race. Here’s how these races are distinctly structured to be engaging and fun while delivering a proper VO2 max session:
- 5 races in less than an hour – that’s 5 hard VO2 max intervals
- Very short efforts: Each race is very short, with a target completion time of 3-5 minutes, just like a good VO2 max interval
- Recovery time: Races are 10 minutes apart, so a 5-minute race leaves you with 5 minutes of recovery before the next interval
- Mix of courses: Each week’s race courses feature a mix of flat, climb, rolling, and even downhill parcours. Riders with lots of pure watts have the advantage in some races, while riders with strong w/kg have the advantage in others.
- Compound Score categories: Since results will be driven by your power numbers, riders will be categorized (A/B/C/D) based on compound score, not Zwift Racing Score. This takes into account your zMAP and body weight. (May 5’s races are categorized based on zFTP, while we work out the proper compound score setup…)
- Mass start: While riders are broken into categories, these are mass start events with all categories starting together, so everyone has riders ahead to chase. (Remember, the goal is to push as hard as you can for the duration of the race, not to sit in the pack and conserve so you can sprint to victory in the last 15 seconds!)
- Drafting is disabled, so these are effectively time trials. (Yes, you’ll want a fast TT setup.) Hopefully this forces you out of the “sit in then sprint” mindset, and into “hold steady high power for the duration” mode.
- GC-Based Final results: overall rankings are based on your cumulative time across the 5 races (see link below).

May 3 Race Details and Signup
Here are the courses for our kickoff races:
- Tempus Fugit (flat): 2.75km, ends 450m after the lead-in finishes
- Quatch Quest (rolling): 2.5km, ends on rollercoaster climb in Titans Grove
- Hilly Route (climb): 2km, ends just after KOM arch because we can’t create events under 2km in length
- Flat Route Reverse (rolling): 2.7km, ends on JWB Bridge
- Jungle Circuit (downhill): 3km, ends on a dusty descent

Sign up at zwift.com/events/tag/vo2sday/ >
Time-Based GC Results
Final GC winners in each category will be available on ZwiftPower at https://zwiftpower.com/league.php?id=3268.
Questions or comments?
If this concept proves popular, I plan to make this into a weekly race series. But I need to hear from you! I’d love to hear your feedback after you complete the first batch of Micros on Tuesday. Share it below, along with any questions or comments you’ve got before the races.