Zone Names and Models

Training zone names and models are not standardised: zones 1 to 7, ReKom to maximal range, and models by Coggan, Friel or metabolic testing all differ.

Definition

“Zone names and models” refers to the various naming systems and calculation methods used to label and delimit training zones. To this day there is neither an international standard for how zones are defined nor for what they are called; there is, however, broad agreement on the basic division. In most cases zones are defined linearly: the “low” zones sit at low power and speed, after which the model steps upward in smaller or larger increments to maximal output.

Why it matters

The real problem is the names: they are common currency, yet carry different content from model to model. Someone saying “zone 2” may mean 56 to 75% of threshold power, 85 to 90% of threshold heart rate, or the range between the economy plateau and the first ventilatory threshold, depending on the source. Without naming the model, a zone reference cannot be interpreted.

In English-speaking countries and with most device manufacturers, zones are simply numbered. Models comprise either 5 zones (heart rate, pace) or 6, sometimes 7 zones (power, rarely pace). In German-speaking countries it is more complex, because exactly the same terms are often used for different divisions. It helps to know the basic idea behind each label:

German label	Usually equals	Basic idea
ReKom (regeneration and compensation)	Zone 1	Active recovery
GA1 (basic endurance 1, base training)	Zone 2	Easy training, defined by physiology and metabolism rather than perceived effort
GA2 (basic endurance 2, development zone, tempo)	Zone 3	Longer race intensities; energy-intensive, long recovery times
Threshold zone (sometimes also “development zone”)	Zone 4	Around the anaerobic threshold or FTP, subdivided further in some models
VO2max / aerobic maximum	Zone 5	Maximal oxygen uptake, short intense intervals, barely controllable by heart rate
Maximal zone	Zone 6	Highest intensities down to neuromuscular work, heart rate no longer responds

GA2 regularly causes confusion because it is unclear why “tempo” should also count as “basic endurance”. The reason is that longer race intensities are planned in this zone. The label “development zone” is misleading here: in a long-term build, zone 3 should be avoided for long stretches, because training there is highly energy-intensive, massively extends recovery times and can exhaust the body lastingly. Athletes who live there can perform at a certain level consistently, but no longer improve. This is known as “zone 3 stagnation”, a precursor to overtraining.

The upper zones add a second problem: intervals in zones 5 and 6 are so short that heart rate, with its response lag, cannot react to them objectively. In a linear comparison, the heart rate calculated for zone 6 sometimes exceeds theoretical maximum heart rate.

How obseed measures it

obseed does not commit to a single naming scheme but works with the reference stored for an athlete. Where data from a metabolic assessment with spiroergometry exists, zones are anchored to the measured physiological functions. Where it does not, only field-test thresholds and percentage ranges derived from them remain, which obseed explicitly treats as estimates. For training control, obseed additionally condenses the zones into three training intensities: LIT, MIT and HIT.

Three methods are the most widespread and are also used by device manufacturers and in performance diagnostics.

Method 1: Percent of a threshold value, heart rate from the pulse at that threshold

The starting point is a threshold value determined in the field or in a lab. It is set as the 100% mark and the zones are derived from it. Because heart rate is usually split into 5 and power and pace into 6 or 7 zones, the number of zones differs. The two most common models come from Dr. Andrew Coggan (power and heart rate) and Joe Friel (power, pace and heart rate).

Heart rate and power zones according to Coggan (threshold = 100%):

Zone	Heart rate (% of threshold HR)	Power (% of FTP)
1	below 69%	below 56%
2	69 – 84%	56 – 75%
3	84 – 95%	75 – 91%
4	95 – 105%	91 – 105%
5	105% and above	105 – 120%
6	–	120% and above

Heart rate and pace zones according to Friel for running (threshold = 100%):

Zone	Heart rate (% of threshold HR)	Pace (% of threshold pace)
1	below 85%	below 78%
2	85 – 90%	78 – 88%
3	90 – 95%	88 – 95%
4	95 – 100%	95 – 100%
5a	100 – 102%	100 – 104%
5b	102 – 106%	104 – 111%
5c	106% and above	111% and above

Unlike Coggan, Friel splits the range around threshold into three sub-zones. According to his theory, zones 1 to 4 cover aerobic and 5a to 5c anaerobic intensities. Whether that holds for a given person can only be verified through a metabolic assessment with spiroergometry; a field test offers no objective insight into metabolic processes whatsoever.

Method 2: Percent of a threshold value, heart rate from the linear profile

This method also defines zones as percentages of a threshold value. Heart rates, however, are not calculated but assigned directly to the intensities actually measured. That requires a linear progression of power and heart rate, which restricts the method to laboratory testing. In return it yields far more objective heart rate values than any calculation.

Method 3: Actual physiological functions, heart rate from the linear profile

To this day, this method can only be applied in the lab with spiroergometry. It produces by far the most individual training zones and the most objective assessment of an athlete’s capacity. Alongside linearly increasing power, the responses of heart rate and metabolism are actually measured, including the lag these systems are subject to.

Zone	Lower bound	Upper bound
1	Start of work	Economy plateau (oxygen cost per watt or per m/s)
2	Economy plateau	Ventilatory threshold 1 (VT1)
3	VT1	95% of VT2 (5% margin for a possible metabolic plateau)
4	95% of VT2	VO2max
5	VO2max	120% of VO2max (cycling) or 115% of VO2max (running)
6	120% or 115% of VO2max	Maximum

The difference between cycling and running comes down to the amount of active muscle mass. Because coordination and technique are secondary on the bike, higher objective outputs can be achieved briefly in the upper zones.

Example

A cyclist has established an FTP of 250 W and a threshold heart rate of 170 bpm in a field test. Coggan’s model yields the following zones:

Zone	Power	Heart rate
1	below 140 W	below 117 bpm
2	140 – 188 W	117 – 143 bpm
3	188 – 228 W	143 – 162 bpm
4	228 – 263 W	162 – 179 bpm
5	263 – 300 W	above 179 bpm
6	above 300 W	–

Three months later, spiroergometry places VT1 at 175 W and 138 bpm and VT2 at 262 W and 168 bpm. Under method 3, zone 2 therefore ends at 175 W rather than 188 W, and zone 3 extends to 249 W (95% of VT2). His previous “zone 2” rides at 180 to 185 W were physiologically already above the aerobic threshold, in precisely the range that fosters zone 3 stagnation over time. The percentage range from the field test was 13 W too generous; only the measurement made the error visible.

References

Allen, H. & Coggan, A.: Training and Racing with a Power Meter.
Friel, J.: The Cyclist’s Training Bible / The Triathlete’s Training Bible.