Tools
Training zones calculator for swim, bike and run
Enter your FTP, run threshold pace or power, CSS or threshold heart rate and get all five training zones for each sport: Recovery, Endurance, Tempo, Threshold and VO2 Max. They are the same zones the LOAD app uses, set from your thresholds rather than your age.
How are these zones set?
Every zone is a fixed share of one threshold per sport. Bike power uses FTP, run pace uses threshold pace, swim pace uses Critical Swim Speed (CSS), and heart rate uses your threshold heart rate for that sport. Change a threshold after a test and every zone moves with it.
| Measure | Z1 Recovery | Z2 Endurance | Z3 Tempobike: Tempo to Sweet Spot | Z4 Threshold | Z5 VO2 Max |
|---|---|---|---|---|---|
| Run pace× threshold pace | slower than 1.29× | 1.14–1.29× | 1.06–1.14× | 0.97–1.06× | faster than 0.97× |
| Run power% of run threshold power | below 78% | 78–88% | 88–94% | 94–103% | 103% and above |
| Run heart rate% of run threshold HR | below 85% | 85–90% | 90–95% | 95–103% | 103% and above |
| Bike power% of FTP | below 55% | 55–76% | 76–95% | 95–106% | 106% and above |
| Bike heart rate% of bike threshold HR | below 81% | 81–90% | 90–94% | 94–103% | 103% and above |
| Swim pace× CSS pace | slower than 1.15× | 1.09–1.15× | 1.03–1.09× | 0.97–1.03× | faster than 0.97× |
Why five zones, and where the edges fall. Friel's and TrainerRoad's seven zones are merged so that Z4 is threshold and just above it, and Z5 is clearly above. That's why heart-rate Z4 runs to 103%: Friel's Zone 5a sits inside it, matching how pace and power treat the same effort. Each zone runs from its lower edge up to where the next one starts, and a value exactly on an edge counts in the harder zone.
- Bike power zones are adapted from the power zones TrainerRoad publishes. Tempo (76–88%) and Sweet Spot (88–95%) are both marked inside Z3, and Supra-Threshold (101–106%) inside Z4. LOAD's Threshold starts at 95% of FTP, rather than around 90% as in Andrew Coggan's power levels, because it follows TrainerRoad's bands, which keep that range as Sweet Spot.
- Run pace and heart-rate zones are based on Joe Friel's zones, merged to five. Pace multiples apply to your time per km or per mile, so a bigger number is slower.
- Run power zones are the run pace zones converted to speed, so pace and power agree on the same run. They're cross-checked against Stryd's zones.
- Swim zones are LOAD's own. No zone system is standard for percentages of CSS, so we use 3% either side of CSS for Threshold, then 6% steps. Heart rate isn't used for swim zones because wrist sensors are unreliable in the water.
- Heart-rate zones are set per sport. Most triathletes reach a lower heart rate on the bike than on the run at the same effort, so one set of heart-rate zones for both would mislead you in one of them.
Zone edges are conventions, not physiology: your body doesn't change state at 76% of FTP. That's why LOAD uses five wider zones rather than seven narrow ones. More on that in Training zones: power, heart rate and pace.
How do I find my thresholds?
With one field test per sport. Common options are a 20-minute all-out ride (FTP is about 95% of the average power), a solo 30-minute run time trial (threshold pace is your average pace, and threshold heart rate the average of the last 20 minutes), and a 400 m and 200 m swim for CSS. Training zones explains each test. If you've had a lactate test, your turn points can set the zones instead; see Lactate thresholds.
How do I work out CSS?
Swim 400 m and 200 m flat out, with a full recovery between them, then subtract the 200 m time from the 400 m time and halve it. That gives your CSS pace per 100 m. Because it comes from the difference between the two swims, a fast 200 m on its own doesn't inflate it. Pace both swims evenly, or the number drifts.
Worked example
| Step | Calculation | Result |
|---|---|---|
| 400 m and 200 m times | 6:00 and 2:50 | 360 s and 170 s |
| CSS pace | (360 − 170) ÷ 2 | 1:35 /100 m |
| Swim Z2 Endurance | 1:35 × 1.09 to 1:35 × 1.15 | 1:44–1:49 /100 m |
Should you trust your zones?
Trust them as a guide, not a rule. Each zone inherits the error of the test it came from, and thresholds move with fitness, fatigue and heat. Heart rate lags and drifts upward on long sessions, so set the session by power or pace and treat heart rate as a check. When sessions keep feeling too easy or too hard for their zone, your threshold has probably moved: retest rather than forcing the numbers. The full case is in Should you trust your zones?
Common questions
Why five zones and not seven?
Zone edges are conventions rather than physiology, so a few wider zones are more honest about how fluid they are. Where a finer distinction matters, such as Tempo and Sweet Spot on the bike, it is marked inside a zone instead of becoming a zone of its own.
Why are my bike and run heart-rate zones different?
Most triathletes reach a lower heart rate cycling than running at the same effort, so each sport has its own threshold heart rate and its own zones.
Why is there no heart-rate zone for swimming?
Wrist heart-rate sensors are unreliable in the water, so swim zones are set from CSS pace instead.
Can I use minutes per mile for running?
Yes. Switch the pace unit to per mile and enter your threshold pace per mile; the zones come back per mile.
How often should I update my thresholds?
Many athletes retest every six to eight weeks, or when sessions keep feeling too easy or too hard for their zone. Spread the three sports' tests out rather than doing them in the same week.
Related
Sources
- TrainerRoad. Cycling power zones: training zones explained. The basis of the bike zone ranges LOAD uses.
- Friel J. Joe Friel's quick guide to setting zones. TrainingPeaks. The basis of the run pace and heart-rate ranges used here.
- Friel J. The Triathlete's Training Bible, 4th edition. VeloPress, 2016.
- Allen H, Coggan AR, McGregor S. Training and Racing with a Power Meter, 3rd edition. VeloPress, 2019.
- Wakayoshi K, Yoshida T, Udo M, et al. A simple method for determining critical speed as swimming fatigue threshold in competitive swimming. International Journal of Sports Medicine. 1992;13(5):367–371. The critical-speed idea CSS builds on; the 400 m and 200 m test is a common simplified version.