By sport
Biathlon Training Zones
Same I1–I5 federation model as XC skiing, with the extra demand of controlling heart rate on the shooting range.
Max Heart Rate Calculator
Your maximum heart rate is the highest your heart can beat in all-out effort. Age formulas estimate it: Tanaka gives 208 − 0.7 × age; the classic 220 − age tends to run high. At age 35 that is roughly 184 and 185 bpm, but the real value varies by ±10–12 bpm, so test it to be sure.
Heart Rate Zone Calculator
Your heart-rate zones are percentages of your maximum heart rate: Zone 1 is 50–60%, Zone 2 60–70%, Zone 3 70–80%, Zone 4 80–90% and Zone 5 90–100%. At a max of 185 bpm, Zone 2, the key aerobic-base zone, runs about 111–130 bpm. Spend most easy training in Zones 1–2.
XC Skiing & Biathlon Heart Rate Zones (I1–I5)
Cross-country skiing and biathlon use the Norwegian/FIS I1–I5 scale: I1 is 60–72% of maximum heart rate (<2 mmol/L lactate), I2 72–82% (~2), I3 82–87% (2.5–4), I4 87–92% (4–6) and I5 92–100% (>6). At a 190 bpm maximum, I1 runs 114–137 bpm and I3 156–165 bpm.