REF-1077 · Olympiatoppen (Skarli, Svendsen, Paulsen, Mentzoni & Losnegard), 2024 · Olympiatoppen
Olympiatoppen's Intensity Scale, Version 2 (2024)
The Norwegian elite-sport centre's eight-zone I-scale (I-1 to I-8) with RPE, %HRmax, %VO2max, lactate, breathing, time to exhaustion, interval and rest rules, an HRmax field test and national-team session models; an expert guideline, not a study, which its authors call guidance rather than a rule
Olympiatoppen's I-scale (Version 2, 2024) is the Norwegian Olympic system's general intensity scale for endurance training (guideline, 2024).
It defines eight intensity zones, each described by internal subjective measures (RPE, perceived breathing), internal objective measures (heart rate, lactate, breathing rate), external measures (power, speed — left for each user to fill in) and session-planning information (total duration, typical interval and rest duration, time to exhaustion).
It adds a five-phase planning-execution-evaluation process, an HRmax field test, caveats for each monitoring tool, a rule for logging intensity, and national-team session models per sport.
The authors state that the scale "serves as guidance and is not meant to be applied rigidly" and recommend that every athlete and coach build an individual scale per sport from lab/field tests and competitions.
Participants
Not a study. The lactate bands in Table 1 are derived from Biosen-analyzer values in 160 elite endurance athletes who run or cycle (web tool; the PDF names only the Biosen analyzer). No other numbers come from a stated sample; they are the working group's expert consensus and national-team practice.
Protocol
Zone definitions (guideline, 2024): Table 1 plus one page per zone (RPE, %HRmax, %VO2max, lactate, breathing, time to exhaustion, total duration, interval duration, rest duration, comment).
HRmax field test (guideline, 2024): 3 × 3 min with 2 min of active rest, intensity rising each interval, the last one to exhaustion.Running example: treadmill or uphill at ~6-10% incline; 15 min warm-up at ~75% of estimated HRmax, then 10 min of gradual increase to ~20 beats below the expected maximum; interval 1 at a pace sustainable for 10-15 min at most, interval 2 at +1 km/h, interval 3 at +1 km/h more and then +0.5 km/h every minute to exhaustion (2 min easy jogging between); the highest recorded HR is HRmax.Retest at least once every three years (HRmax normally declines with age); test each relevant modality separately.
Session models (guideline, 2024): web-tool tables of national-team sessions for cycling, running (1500 m to marathon), triathlon and swimming (Norwegian-language images).
Key Results
The eight I-zones (guideline, 2024). Table 1 values first; where the zone page differs, both are given.
| Zone | RPE Borg 6-20 / CR10 | %HRmax | %VO2max | Lactate (Biosen) | Breathing / talk | Time to exhaustion |
|---|---|---|---|---|---|---|
| I-1 very light | <11 / 1-2 | ~55-72% | ~45-55% | <1.5 mmol/L (zone page ~0.5-1.0) | can speak effortlessly; typically <30 breaths/min | several hours for an elite cyclist |
| I-2 fairly light | <13 / 2-3 | ~72-82% | ~55-72% | ~1.0-2.0 mmol/L | longer sentences relatively effortlessly; typically <30 breaths/min | normally ~3-6 h (much shorter in kayak, skating) |
| I-3 somewhat hard | 13-14 / 4-5 (zone page prints <13 / 2-3, apparently copied from I-2) | ~82-87% | ~70-80% | ~1.5-3.5 mmol/L | short sentences; typically 30-50 breaths/min | ~1-2 h |
| I-4 hard | 14-16 / 6-7 (zone page Borg 15-16) | ~87-92% | ~75-85% | no value given (needs experience) | a few words or very short sentences; typically >40 breaths/min | ~45 min (large individual spread) |
| I-5 very hard | 16-19 / 8-10 (zone page Borg 17-19) | ~92-100% (zone page "~92%") | ~85-100% | no value given (depends on session model) | one or two words while breathing heavily; typically >40 breaths/min | ~20 min at a constant external load |
| I-6 very, very hard | 19-20 / 9-10 | not applicable | not applicable | not applicable | only a few short words, gasping | ~4 min |
| I-7 very, very hard | 20 / 10 | — | — | maximal, but not recommended for steering (it keeps rising after the rep) | not applicable | ~1 min |
| I-8 maximal mobilisation | — | — | — | — | not applicable | ~15 s |
Running time to exhaustion, well-trained runner (guideline, 2024; Table 4): I-2 ~3 h; I-3 ~60 min (~half-marathon speed); I-4 ~30 min (~10 000 m speed); I-5 ~15 min (~3000/5000 m speed); I-6 ~4 min (~800-1500 m); I-7 ~1 min (~200-400 m); I-8 ~15 s (~60-100 m).
Table 3 — suggested duration per session in each zone for a high-level cyclist (guideline, 2024; interval zones = total interval time):
| Zone | Developmental session | Maintenance session |
|---|---|---|
| I-1 | ~180-420 min | ~120-240 min |
| I-2 | ~120-240 min | ~60-120 min |
| I-3 | ~60-90 min | ~45 min |
| I-4 | ~40-60 min | ~30 min |
| I-5 | ~30 min | ~15 min |
| I-6 | ~15 min | ~6-8 min |
| I-7 | ~5 min | ~2-3 min |
| I-8 | ~1-3 min | ~0.5-1 min |
Interval duration per zone (guideline, 2024): I-1 and I-2 continuous (I-2 can be long segments with short breaks); I-3 typically 8-20 min reps (sometimes as short as 1 min); I-4 3-10 min (shorter with microbreaks); I-5 30 s (with microbreaks) up to 5 min; I-6 ~30 s-2 min; I-7 15-60 s; I-8 3-15 s.
Total duration per session (guideline, 2024): I-1 45 min or more in running, much longer in cycling; I-2 45 min-3 h; I-3 20-90 min; I-4 often 20-50 min; I-5 often 15-30 min; I-6 and I-7 a few minutes; I-8 <1 to 3 min of work. I-2 makes up 10-20% of total volume in several endurance sports.
Rest duration per zone (guideline, 2024): I-1 not applicable; I-2 none, or microbreaks of 10-30 s / up to 2-3 min in technical or muscular sports; I-3 ~25% of the interval duration or 1-3 min; I-4 often ~50% of the interval duration; I-5 often ~50-75% (longer before competitions); I-6 at least 100-200% of the interval duration, sometimes up to 10 min; I-7 5-15 min; I-8 3-15 min.The general section says rest grows from 2 min and beyond in I-3 to 3-5 min in I-5, and 5-15 min in I-6 to I-8. Shorter rest forces a slightly lower intensity in the reps; too short a rest degrades technique; muscular load and higher rep intensity both call for longer rest.
Cycling national-team session models (guideline, 2024; web-tool table "Øktmodeller fra sykkel", work/rest, total work time, session length):
I-1: long ride, session 2-7 h; sometimes combined with sprints (I-7, I-8) or natural intervals. I-2: long ride, 1-3 h.
I-3 (session 1.5-3 h): 4-6 × 15 min / 2 min (60-90 min work); 7-8 × 10 min / 3 min (70-80 min); 60-min FTP test, no rest (60 min); 2 × 30 min / 5 min (60 min); natural intervals inside a long ride. Comment: the first rep is commonly ridden a little easier as a run-in rep.
I-4 (session 1.5-2 h): 20 × 3 min / 30 s (labelled I-zone 3-4), the first 7 reps at 95% of FTP and the rest at 105% (60 min); 8 × 6 min / 3 min (48 min); 10 × 5 min / 2 min (50 min); 5 × 10 min with "toppers" — (90 s at 95-100% FTP + 30 s at 125% FTP) × 5 — / 2 min (50 min); 7 × 3 min with 8 min in I-2/I-3 between (21 min). Comment: also often starts with an easier run-in rep; a hard I-4 session can approach I-5 towards the end.
I-5 (session 1-1.5 h): 6 × 6 min / 3 min (labelled I-zone 4-5), each rep starting with a 30-s surge ("topper") (36 min); 30/15 × 13 × 3 — 30 s at 125-130% FTP and 15 s at 50% FTP — with 3 min between sets (30 min); 5 × 5 min / 2.5 min (25 min); pyramid 8-7-6-5-4 min / 2 min (30 min). Comment: the rider should be able to hold the same or a higher external load on the last reps as on the first.
I-6: 6 × 2 min / 5 min (12 min); combined with longer I-1/I-2 rides or other interval forms, placed at the start for the freshest muscles, or towards the end when more race-specific work is wanted.
I-7: 1-3 sets of 3 × 30 s long sprints / 4 min (4.5 min); own sessions or inside I-1/I-2 long rides; maximal or near-maximal effort.
I-8: 6-8 × 10 s sprints / 3 min (1-1.5 min); inside long rides or as pure start sessions; maximal effort.
Running national-team I-3 (guideline, 2024; "Øktmodeller fra løping"): threshold long intervals, e.g. 8-15 × 1000 m (10-12 typical) with 25 s-2 min rest; sessions designed to sit at 1.5-3.5 mmol/L; for elite runners a session held steadily under 2.0 mmol/L is still classed I-3 because the speed is high; in the "double threshold" model the morning session typically sits at 1.5-2 mmol/L and the evening one slightly higher.
HRmax (guideline, 2024): the same athlete can have ~5% higher HRmax running than cycling (the guideline cites Millet et al. 2009 — in this base as REF-537); HRmax varies widely at any age (Tanaka 2001 figure), so it should be measured, not estimated from age.
Heart-rate caveats (guideline, 2024): good for continuous work and for intervals long enough for HR to stabilise (>4 min); daily variation ~6-12 beats (citing Bagger 2003 and Lambert 1998), moved by altitude, climate, hydration, glycogen and mental stress; HR lags at the start of work, so it is poor for short high-intensity intervals or constantly changing loads; HR drifts upward in long sessions at a constant load, more in heat or dehydration; a lower HR at the same external load usually means improved fitness, but — especially at very high intensity — can also mean too much total load or insufficient recovery (citing Bosquet 2008, Meeusen 2013); wrist HR has a considerable error, use a chest strap; HRmax must be measured and kept up to date.
Lactate caveats (guideline, 2024): a good measure in I-1 to I-3 and for tracking progress on an identical session model; at I-4 and above lactate may not consistently reflect intensity unless the athlete has extensive experience or repeated measurements on the same session model (and in I-7 it is not recommended for steering); handheld analyzers do not give comparable values (citing Mentzoni et al. 2024), small samples risk error (e.g. sweat), so use the same handheld meter over time with meticulous technique; low glycogen stores can give artificially low lactate and underestimate intensity; values differ between modalities (running vs cycling) and between individuals.
Breathing and RPE caveats (guideline, 2024): breathing rate gives faster feedback than HR or lactate in short reps but is elevated at altitude and is not measured reliably by current watches or bike computers; RPE rises across a session at the same external load, is less reliable in I-1 and I-2 and between athletes, and can miss muscular load (e.g. downhill running).
Quantification (guideline, 2024): HR time-in-zone underestimates the high zones in short intervals — in 15 × 1 min / 1 min the monitor may show only 7-8 min in I-5, so log all 15 working minutes as I-5; in I-8 (and commonly I-6, I-7) log the rest periods as part of the work time (10 × 10 s / 2 min = 20 min of I-8); at low, steady intensities HR is the better measure to log; above all, log the same way every time.
Practical Application
"What do the Norwegian I-zones mean, and is their I-3 my threshold?" Olympiatoppen's 2024 guideline (expert consensus for elite athletes; lactate bands from 160 elite runners and cyclists) puts I-3 at ~82-87% HRmax and ~1.5-3.5 mmol/L with 8-20 min reps and a time to exhaustion of ~1-2 h — mostly below FTP — while the two national-team I-4 sessions that give a %FTP are set at 95-105% (20 × 3 min, the first 7 at 95% and the rest at 105%; 90 s at 95-100% + 30 s at 125%), so what Blocks and most cycling apps call "threshold" corresponds more closely to I-4 and the top of I-3. The 60-min FTP test is listed among the I-3 sessions, which suggests FTP sits near the upper edge of I-3 rather than in its middle (guideline, 2024; the mapping to Blocks zones is inference).
Session design by zone (guideline, 2024): rest ~25% of the rep (or 1-3 min) in I-3, ~50% in I-4, ~50-75% in I-5, ≥100-200% in I-6 and 5-15 min in I-7/I-8; per-session doses for a high-level cyclist are in Table 3 (e.g. I-4 ~40-60 min to develop, ~30 min to maintain).
HRmax (guideline, 2024): measure it with the 3 × 3 min progressive test, separately per sport (running ~5% higher than cycling), at least every three years; never assume an age formula.
Inference, not tested here: when an athlete or coach speaks in Norwegian I-zones, translate by the descriptors (lactate, breathing, reps, time to exhaustion) rather than by the zone number, and individualise the bands as the authors require.
Limitations
Not a study: an expert guideline from one national elite-sport centre; no zone, dose or session model is compared with an alternative, so nothing here shows that one works better.
The authors' own caveats: the scale is general guidance for Norwegian athletes and coaches, "not a definitive answer for every situation and individual"; values vary with modality, level, age, functional impairment and the individual, and each athlete should build an individual scale per sport; it is based on leg and whole-body sports and may mislead for seated, upper-body para-sport.
Only the lactate bands rest on data (160 elite runners and cyclists, Biosen analyzer; the sample is described only on the web tool); handheld meters give different values. %HRmax, %VO2max, breathing rates, times to exhaustion and durations are consensus.
Internal inconsistencies between Table 1 and the zone pages (I-1 lactate <1.5 vs ~0.5-1.0 mmol/L; I-3 RPE 13-14 / 4-5 vs <13 / 2-3; I-4 Borg 14-16 vs 15-16; I-5 %HRmax 92-100% vs ~92%; I-4 time to exhaustion ~45 min on its page vs ~30 min in the running table).
Table 3 doses are for a high-level cyclist; the session models are national-team practice and come as Norwegian-language images on the web tool, not in the PDF.
Elite and high-level population; transfer to recreational or time-limited athletes is inference.
How this entry was checked and changed
Why this level
(expert guideline: the lactate bands come from 160 elite runners and cyclists measured on a Biosen analyzer, per the web tool; every other number is expert consensus and practice; the authors call the scale guidance, not a rule)
Content correction 2026-09-27
Verification 2026-10-04: only two of the five national-team I-4 cycling models give a %FTP — the 95-105% claim narrowed to those two; the FTP-at-the-upper-edge reading is marked as inference.