Friel's LTHR test: 30 minutes on your own, as fast as you can, on a flat route. Your average heart rate over the last 20 minutes gives your lactate threshold heart rate, and your average pace, an estimate of threshold pace. 55 minutes, no blood test.
| Target | Zone | Time | vVO₂max 14 km/h | vVO₂max 16 km/h | vVO₂max 18 km/h |
|---|---|---|---|---|---|
| 86–92% | 4Threshold | 30 min | 4:59/km–4:40/km | 4:22/km–4:05/km | 3:53/km–3:37/km |
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Do the test from your watch, guided block by block. Then enter your new reference speed and every session follows.
This test doesn't make you fitter: it estimates your lactate threshold heart rate (LTHR), with no lab and no blood test. It's the heart rate you can hold for an effort of about an hour, and Joe Friel builds his heart-rate zones on it: each zone is a percentage of LTHR rather than of maximum heart rate.
Why 30 minutes solo rather than an hour? Because, according to Friel, running alone brings the intensity down compared with racing: 30 minutes on your own comes close to what you'd hold for an hour in a race. As a bonus, the test gives you your average pace over the last 20 minutes, an estimate of threshold pace that's handy for setting your tempo runs.
Regular runners who can run for 30 minutes at a sustained pace and who train, or want to train, by heart rate. It suits runners building towards a half marathon or a 10K, where the effort sits close to threshold, and triathletes who set their run zones by heart rate. If you're after your interval paces, a vVO₂max test such as the Cooper test or the half Cooper is more direct.
At the end of a training cycle, or every 4 to 8 weeks: a common guideline. Do it fresh, after one or two easy days, never the day after a hard session. Eat lightly 2 to 3 hours before, and avoid heat and strong wind: heat pushes your heart rate up for reasons that have nothing to do with your threshold. Repeat it on the same route, in the same shoes, so your results compare.
10′ at 60–65% vVO₂max + 5′ at 66–72% vVO₂max
10 minutes of easy running at 60–65% of vVO₂max, then 5 minutes a little brisker, at 66–72%. Check your chest strap is connected, and set your watch to mark a lap at minute 10 of the test, or be ready to press the button.
10′ at 86–92% vVO₂max
10 minutes, the start of a 30-minute flat-out effort. Set off at the pace you think you can hold to the end, no faster: these 10 minutes don't count towards the result, but a start that's too quick spoils the next 20. Guide: 86–92% of vVO₂max, or 4:22 to 4:05/km at 16 km/h. Don't look at your heart rate: run by feel, as Friel advises.
20′ at 86–92% vVO₂max
20 minutes with no stops and no easing off: this is the part that's measured. Hold the same pace, and wind it up over the last 5 minutes if you have anything left. No stopping, no traffic lights: pick a flat, clear route, road or track. Waiting at a pelican crossing is not part of the protocol.
10′ at 55–65% vVO₂max
10 minutes of very easy running at 55–65% of vVO₂max, starting with a few steps of walking. Then the maths: your LTHR is your average heart rate over the lap covering the last 20 minutes. An average of 172 bpm between minutes 10 and 30 gives an LTHR of 172 bpm. Note your average pace for that lap too.
The pace of a 30-minute race: hard but steady, breathing deep and rhythmic. The last 5 minutes are very hard, but you should be able to hold them without falling apart. Guide: 8 to 9 out of 10. If you finish at 10 out of 10 and slowing, you probably went off too fast.
Heart rate takes several minutes to rise and settle at the start of an effort. Average the full 30 minutes and that lag drags the figure down, so your LTHR comes out too low. Only the lap covering the last 20 minutes counts.
Running in a group, or in a race, pushes your intensity up: according to Friel, your result no longer matches the solo protocol. Run the test alone, or use the one-hour race version.
A watch's optical sensor can misread a sustained effort, especially in the cold or with a lot of arm movement. A chest strap gives a more reliable reading: it's what you want for this test.
Aiming for a heart rate during the test skews the very thing you're trying to measure. Run by feel, at the limit of what you can hold for 30 minutes, and only look at your heart rate afterwards.
A method from Joe Friel, the American coach, described in The Triathlete's Training Bible (VeloPress, several editions) and in his writing on heart-rate training: 30 minutes solo, as fast as possible, with the average heart rate over the last 20 minutes as an estimate of lactate threshold heart rate. Friel himself presents the result as an estimate. No reference validation study was found in the sources consulted. The 86–92% vVO₂max range during the test, the warm-up and the cool-down are Wattson choices; during the test those targets are only guides. Bottom line: a very widespread coaching method, easy to repeat, moderate confidence.
Mark a lap at minute 10 of the test, then take the average heart rate for that lap, from minute 10 to minute 30: that's your LTHR. An average of 172 bpm gives an LTHR of 172 bpm. Friel presents the result as an estimate, so repeat the test regularly to confirm it.
Because your heart rate takes several minutes to catch up with your effort. Early in the test it lags behind your pace; over the last 20 minutes it reflects the intensity you're really holding. The first 10 minutes are there to settle into the effort, not to measure it.
Both are used. Friel prefers LTHR: it's measured on a real effort close to what you race, whereas max heart rate is hard to reach and varies a lot between runners. If your training tool works out your zones from max heart rate, keep that setting and use the test to track your fitness.
No. Over 30 minutes you run well below your vVO₂max: the test gives your LTHR and an estimate of threshold pace, not your maximal aerobic speed. To measure vVO₂max, do a short test such as the half Cooper or the VAMEVAL.
Every 4 to 8 weeks, or at the end of a training cycle: a common guideline, not a rule drawn from studies. Repeat it in the same conditions, same route, same time of day, same shoes, and at a similar temperature: heat pushes your heart rate up.
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