Use intensity zones to describe the work you intend to do, then check that the athlete is actually doing it.
Two sessions can both be labelled “threshold” and still place very different demands on an athlete. Different zone systems, individual thresholds and changing terrain all contribute to that confusion.
Olympiatoppen’s intensity scale provides a shared framework from I-1 to I-8. Its value comes from combining the purpose of the session with several measures of intensity. A zone number is a description, not a complete workout.
First, agree which scale you are using
Olympiatoppen’s eight-zone scale is not interchangeable with every five-zone watch setting or coaching system. An easy session labelled Z2 in one system should not automatically be recorded as I-2 in another.
Before discussing time in zones, agree on the scale, how its boundaries were established and how the training was recorded. Time assigned to a session’s intended intensity is also different from minute-by-minute heart-rate time in zone.
Read the scale as a set of guides
The official scale combines perceived exertion, breathing, heart rate and other relevant measures. It also gives space for individual pace or power values. The following is an overview for interpretation; use the official interactive scale for its detailed reference ranges.
| Part of the scale | Main practical interpretation | Useful control |
|---|---|---|
| I-1 and I-2 | Lower-intensity endurance work | Breathing, perceived effort, duration and individual heart-rate response |
| I-3 | Controlled work near the athlete’s threshold region | Individual response, repeatability and, where appropriate, well-interpreted lactate testing |
| I-4 and I-5 | Progressively harder aerobic interval work | Effort, repetition quality, recovery and heart-rate response over time |
| I-6 to I-8 | Shorter, faster work with substantial demands beyond those captured by heart rate | Speed, duration, technical quality and sufficient recovery for the intended task |
These are practical groupings, not claims that each zone activates a separate energy system. Aerobic and anaerobic contributions overlap. Even very hard running cannot be described accurately as “purely anaerobic”.
Use more than one signal
Heart rate is helpful during sustained work but responds with a delay. Chasing a target value in the first seconds of a short repetition can make you start too fast. Heat, fatigue and other conditions can also change the relationship between pace and heart rate.
Perceived effort and breathing provide context. Lactate is an internal response, not an external workload measure, and one universal concentration cannot define the same physiological intensity for every athlete. Olympiatoppen explicitly notes substantial individual variation in its reference values.
Pace is useful on repeatable surfaces. In a forest, the same effort may produce very different speeds on a path, a rocky slope and soft ground. That is a feature of the task, not necessarily a failure to control the session.
Apply it to orienteering
Consider an easy technical session. The goal may be accurate control exits at a comfortable effort. A short rise in heart rate on a hill does not automatically change the purpose of the whole session, but repeatedly racing climbs may undermine it.
Now consider hard orienteering intervals. A low average heart rate may reflect stops caused by navigation, rather than a well-controlled physiological session. Review the route and the pauses alongside the watch data. If the objective is sustained aerobic work, a simpler map or separate physical session may be more appropriate.
Source
- Olympiatoppen: official intensity scale and guidance. The interpretation and orienteering examples above are coaching applications of the scale.