Guides
I1–I8 intensity zones
Nordic cross-country training often classifies intensity in zones from easy endurance work to maximum sprints. Zones are personal and change with fitness.
From I1 to I8
The lower zones cover aerobic base and recovery, the middle zones threshold work, and the upper zones race and sprint intensity. I8 means short maximum sprints.
Personal zones
Zones are based on each athlete’s maximum heart rate, tests and lactate. Workout templates use I1–I8, not fixed heart rate values.
Preserving history
New zones apply from the date they are recorded. Older workouts retain the classification that applied at the time.
Intensity distribution
Statistics show the share of training time spent in each zone — a clear way to see whether training follows the plan.