Stephen Seiler1 and Espen TønnessenSportscience 13, 32-53


– Most national sports use an intensity scale based on ranges of HR relative to maximum and associated blood lactate concentration range
– Research approaches vary, but a number of recent research studies have identified intensity zones based on ventilatory thresholds
– Here we will examine an example of each of these scales.
– Table 1 shows the intensity scale used by all endurance sports in Norway.
– A valid criticism of such a scale is that it does not account for individual variation in the relationship between heart rate and blood lactate, or activity specific variation, such as the tendency for maximal steady state concentrations for blood lactate to be higher in activities activating less muscle mass (Beneke and von Duvillard, 1996; Beneke et al., 2001).

Table 1: A typical five-zone scale to prescribe and monitor training of endurance athletes.
Intensity zone VO2


Heart rate (%max) Lactate (mmol.L-1) Duration within zone
1 45-65 55-75 0.8-1.5 1-6 h
2 66-80 75-85 1.5-2.5 1-3 h
3 81-87 85-90 2.5-4 50-90 min
4 88-93 90-95 4-6 30-60 min
5 94-100 95-100 6-10 15-30 min
The heart rate scale is slightly simplified compared to the actual scale used by the Norwegian Olympic Federation, which is based primarily on decades of testing of cross-country skiers, biathletes, and rowers.


– Elite endurance athletes train 10-12 sessions and 15-30h each week.
– Is the pattern of 80% below and 20% above lactate threshold appropriate for recreational athletes training 4-5x and 6-10 hrs/wk?
– Esteve-Lanao did a study on recreational runners comparing a program designed to reproduce polarized training of successful endurance athletes and compare it with a program built around much more threshold training in keeping with the ACSM guidelines
– The intended intensity distribution for the 2 training groups was:
(1) Polarized 77-3-20 % and ACSM 46-35-19 % for Zones 1, 2, and 3.
(2) However, heart-rate monitoring revealed that the actual distribution was: Polarized 65-21-14 % and ACSM 31-56-13 %.
– Comparing the intended and achieved distributions highlights a typical training error committed by recreational athletes.
– We can call it falling into a training intensity “black hole.”
– It’s hard to keep recreational people training 45-60 min/day 3-5 days/wk from accumulating a lot of training time at lactate threshold
– Training intended to be longer and slower becomes too fast and shorter in duration, and interval training fails to reach desired intensity
– The result is that most training sessions end up being performed at the same threshold intensity.
– Foster 2001b: found that athletes tend to run harder on easy days and easier on hard days, compared to coaches’ training plans
– Esteve Lanao did succeed in getting 2 groups to distribute intensity very differently.
– The group that trained more polarized, with more training time at lower intensity, improved 10-km significantly more at 7 and 11 wks
– So, recreational athletes could also benefit from keeping low- and high-intensity sessions at the intended intensity.


– Interval training can be performed effectively with numerous combinations of work duration, rest duration, and intensity.
– Self-select run speed of 4-min work and 2-min recovery gives the highest physiological response and maintained speed
– NOTE: See the research article by Seiler that shows 4×8 min to be superior for the Bike → CLICK HERE
– However, perceptual and physiological response differences across the work and recovery spectrum are fairly small
Studies and our observations suggest that a variety of combinations of work and rest duration are effective for long-term development
– Table 6: All the examples are taken from the training diaries of elite endurance athletes
– For those without the same training base, similar workouts would be performed but with less total effective duration

Table 6. Typical training sessions performed by highly trained athletes in five intensity zones (Aasen, 2008).
Zone VO2 (%max) Examples of training sessions Manageable durationa
1 45-65 Continuous bouts 60-360 min
2 66-80 Continuous bouts 60-180 min
3 81-87 6 x 15 min, 2-min rec

2 x 25 min, 3-min rec

5 x 10 min, 2-min rec

8 x 8 min, 2-min rec

LT 40-60 min

50 x 1 min, 20-s rec

50-90 min


4 88-93 10 x 6 min, 2-3-min rec

8 x 5 min, 3-min rec

15 x 3 min, 1-min rec

40 x 1 min, 30-s rec

10 x (5 x 40 s, 20-s rec),
2- to 3-min breaks

30-40 min steady state

30-60 min
5 94-100 6 x 5 min, 3-4-min rec

6 x 4 min, 4-min rec

8 x 3 min, 2-min rec

5 x (5 x 1 min, 30-s rec),
2- to 3-min breaks

24-30 min
Warm-up and rest periods in interval bouts are not included.

LT, lactate threshold (max steady state); rec, recoveries.

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