Any test will do, as long as you run it flat out
You do not need a laboratory. Any maximal effort between 5 and 20 minutes serves to estimate your aerobic capacity and, from there, your paces by zone. The 12-minute Cooper test, a 1 km, a 5 km or simply your last local race are all valid points on the same curve.
The relationship between distance and time in a runner follows a fairly stable power law, Riegel's, which is what allows one distance to be predicted from another:
The 1.06 exponent is the population average. A runner with deep endurance and little speed has a lower exponent, close to 1.03, and "holds on" better as the distance grows; a sprinter with low mileage can go above 1.10 and collapse in the marathon. That is why a marathon predicted from a 5 km is the least reliable of all, and should be treated as the optimistic ceiling rather than the target.
Paces come from physiology, not from race pace
Once you have the test, zones are derived as percentages of your maximal aerobic speed or your threshold pace. The classic recreational runner's mistake is training everything in a grey zone: too fast for the easy run to be easy, too slow for the interval to stimulate anything. The gap between easy pace and threshold pace should be uncomfortably large.
| Zone | % of threshold pace | Feel | Typical duration |
|---|---|---|---|
| Easy | 75 – 84 % | Comfortable conversation | 30 – 150 min |
| Marathon | 84 – 90 % | Short sentences | 60 – 180 min |
| Threshold | 95 – 100 % | Single words | 20 – 60 min |
| VO2max | 105 – 112 % | No talking at all | 3 – 8 min per rep |
| Speed | > 115 % | Maximum technical control | < 2 min per rep |
And then there is the terrain
A 5:00 per kilometre on the flat is not the same effort as 5:00 climbing at 6 %. The energy cost of running rises very fast with positive gradient and falls only slightly with negative gradient, until the descent gets steep enough that braking costs more than moving forward. That asymmetry is why you lose far more climbing in a trail race than you recover descending.