How we measure
Six numbers. Nothing hidden.
Every number your coach reads, with the formula behind it, in plain words. Check our work any time.
A Tuesday in a build week
- Drive
- 85
- Throttle
- 0.85
- Depth
- 62
- Carry
- 71
- Bounce
- -9
Bounce below zero in a build week means the work is landing. It comes back up on the easy days.
The six numbers
Three describe one session. Three describe you over time. All six use the same scale, so a ride, a run and a swim add up.
Drive
How far one session moved you forward.
The formula
Drive = hours × Throttle² × 100
An hour flat out at your threshold is 100. An easy hour is about 40 to 60. Days and weeks add their sessions up.
Why it matters
It puts every sport on one scale, so your coach can balance a hard ride against an easy run and know what the week really cost.
Steady Watts
The steady power that would have cost you the same as that ride.
The formula
Steady Watts = ⁴√(average of (30-second power)⁴)
We smooth your power over 30 seconds, raise each value to the fourth power, average them, and take the fourth root. Surges count for more than their average, because your body pays more for them.
Why it matters
A punchy group ride and a smooth solo ride can share an average power and feel nothing alike. Steady Watts tells them apart.
Throttle
How far you opened it up against your threshold.
The formula
Throttle = effort ÷ threshold
On the bike, Steady Watts ÷ your FTP. On the run, grade-adjusted pace ÷ your threshold pace. In the pool, pace ÷ your critical swim speed. 1.00 is threshold.
Why it matters
It tells your coach how hard a session was for you, not for someone else, so the same plan works at any level.
Depth
What the last six weeks built. It moves slowly, and it stays.
The formula
Depth today = Depth yesterday + (Drive today − Depth yesterday) ÷ 42
A rolling average of your daily Drive that weighs recent weeks most and fades older ones over about six weeks.
Why it matters
This is the fitness you race on. Your coach grows it a little each week, never in jumps, so it lasts.
Carry
What this week still has in your legs. It fades fast.
The formula
Carry today = Carry yesterday + (Drive today − Carry yesterday) ÷ 7
The same rolling average over about a week, so it rises fast after hard days and drops fast when you rest.
Why it matters
Carry is the work your body is still turning into Depth. Your coach reads it to place easy days where they help most.
Bounce
How fresh your legs are for race day.
The formula
Bounce = Depth − Carry
Positive means fresh. Around zero means training steady. Below zero means you are in a building block, which is normal and good.
Why it matters
Your coach builds Bounce back up before your race with a taper, so you start fresh with all your Depth.
Where Drive comes from
Every session gets a Drive. We use the best data the session has, in this order, and stop at the first one that works.
- Power Rides with a power meter: Steady Watts against your FTP.
- Pace Runs, walks and hikes: grade-adjusted pace against your threshold pace, so hills count for what they cost. Swims: pace against your critical swim speed, with Throttle cubed, because water resistance climbs fast.
- HYROX stations Station data from your race or simulation, for mixed work that pace alone misses.
- Heart rate Time in zones around your threshold heart rate: 35, 60, 77, 100 and 125 per hour from zone 1 to zone 5. Without a threshold heart rate, we estimate from your average and maximum heart rate.
- Effort Your rating of the session, 1 to 10, times hours, times 10. An all-out hour is 100, so strength and gym work sit on the same scale.
- Time Nothing else recorded? We count the time at an easy effort, so every session still counts without inflating your week.
Yours to tune
Depth averages over 42 days and Carry over 7 by default. You can change both in Settings, under Thresholds & zones. Your thresholds update as you get fitter, and your coach tells you when they move.
Moving from TrainingPeaks
Same ideas, our names.
Bring your history with you. We rebuild your Depth, Carry and Bounce from your files, day by day, and show how close they land to what you saw before. An hour at threshold is 100 here too, so your numbers stay familiar from day one.
See how to switchTrainingPeaks is a trademark of its owner. Athlete Space is not affiliated with TrainingPeaks or Garmin.
The bottom line
You train. Your coach reads these six numbers every day and handles the rest.
Drive, Steady Watts, Throttle, Depth, Carry and Bounce are trademarks of Athlete Space.