Enter your bike and/or run lactate threshold heart rate, we compute zones for both sports, including a dedicated Zone 2 band that’s the difference between “easy” and “genuinely aerobic”. Run zones shift higher than bike zones because heart rate runs higher at threshold in running than cycling.
Enter the sport(s) you want zones for. Don’t use HRmax estimates, LTHR is the right anchor for endurance training. If you don’t have it, see how to test for it below.
Three ways, in increasing order of accuracy.
Warm up. Then ride or run as hard as you can sustain for 30 minutes solo, no training partners, no negative split. Your average HR for the final 20 min is your LTHR. Test bike and run separately on different days. Most accurate field method.
A well-paced 40 km TT (bike) or ~10 km race (run) average HR ≈ LTHR for most athletes. Cleanest if the race was a true effort with steady pacing throughout.
MLSS (maximal lactate steady state) or VT2 (ventilatory threshold) measured via blood lactate sampling or gas exchange. The lab number doesn’t care about your pacing or the weather, it’s the threshold itself.
Retest every 4–8 weeks or after any obvious fitness shift. Pitfalls: using HRmax formulas (220 − age etc.) gives a band that’s wrong for most athletes by ±10 bpm. Heat, dehydration, caffeine, and altitude shift HR by 5–10 bpm. HR also lags on short intervals, zones work best for steady efforts, not 30-second on-off intervals.
This trips people up: at the same metabolic intensity, your run HR sits 5–10 bpm higher than your bike HR. Reasons:
Don’t reuse one LTHR across sports. Test each separately, set zones independently. Athletes who do this correctly stop "blowing up" on the run leg of races because they were using bike-zone caps.
For the most accurate version, lab testing measures both sport-specific thresholds plus the metabolic crossover point that drives your fueling, same morning, single visit.
Six zones, six different jobs. Train them on purpose.
Active recovery, easy spinning, post-hard-day shake-out. Below the aerobic floor. Should feel like nothing, that’s the point.
Where mitochondrial density and fat oxidation get built. Long, frequent, conversational. Most endurance gains live here. Boring on purpose.
Above Zone 2 but below threshold. Race-pace effort for events 1–4 h. Builds aerobic durability for long races. Use sparingly, tempo accumulates.
Sustainable for 30–60 min. Trains your ability to clear lactate at high intensity. 1 session/week max in most blocks, the cost is real.
3–8 min intervals. Pushes oxygen uptake ceiling. Feels brutal; should. 1 session/week, often only in specific blocks.
Sub-2-min full-gas reps. Sprint training, high-power neuromuscular stimulus. Use sparingly outside sprint specialists.
The bike power equivalent of LTHR, closely tracks bike threshold for most athletes.
Open → Running time predictorOnce your zones are right, project realistic finish times across distances.
Open → All calculatorsBack to the full catalog, 30+ endurance calculators across performance, fueling, swim, bike, run.
Browse →Lab testing measures your actual LTHR via blood lactate or gas analysis, in a single morning we test bike and run thresholds plus your fat/carb metabolic crossover. Zones built on real numbers beat zones built on field-test guesses.
Spotted a bug or want a feature? Email info@yousuli.co.
