What threshold means, and finding yours without a lab
Threshold, on this page, is the upper of the two thresholds physiologists measure: the fastest pace at which the lactate in your blood holds steady instead of climbing. Go faster and it builds until you have to slow down. Stay at it or just under and you can keep going. Researchers put it at a speed a well-trained distance runner can hold for about an hour, close to half-marathon pace in elite runners.
It feels comfortably hard: a few words at a time, not a conversation. Three ways to find it:
- A 30-minute time trial. After a warm-up, run 30 minutes alone, as hard as you can hold evenly, on a track, a flat loop or a treadmill. Your average pace is your first estimate of threshold pace, and the heart rate you settle at is a first estimate of your threshold heart rate. In a study of 27 competitive distance runners and triathletes, both came out close to the values measured with blood samples in a lab. It is a hard session, so make it that week's hard run.
- A recent race of about an hour. If you race 10 km in about an hour, that pace is close to your threshold. If your 10 km is much quicker, your threshold sits a little slower than 10 km pace, towards half-marathon pace.
- The talk test. In a 2026 study of 14 recreational athletes, the point in a graded test where they could no longer speak comfortably matched the upper threshold measured from their breathing. Whole sentences mean you are under it.
Coach Tiago Lousa suggests a way to watch threshold move: every four weeks, after 20 minutes easy, run 30 minutes at the same pace near threshold and note your average heart rate. When it has come down over a few months, raise the pace.
Why threshold work suits the runs in a HYROX
Start with how successful distance runners train. A study of 85 elite and world-class male long-distance runners asked what they did in their first seven years. Easy runs and tempo runs were the training types that best predicted how fast they became. Short-interval sessions also went with faster times; long intervals much less so. These are runners recalling their training, not HYROX athletes in a trial, but the shape matches the rest of endurance sport: competitive athletes do about 80 percent of sessions easy and about 20 percent hard. Keeping the easy part easy is covered in Zone 2 for HYROX.
Then look at the race: eight runs of about 1 km between eight stations. In the first scientific study of the race, 11 recreational athletes each raced a simulated HYROX alone in a gym and took a median 86.5 minutes. The typical heart rate averaged 170.9 beats per minute, and for about four-fifths of the race it sat at 90 percent of maximum or higher. In the Pro division, a study of 24 men at HYROX Madrid 2025, finishing in about 70 minutes, found that their running, with the transitions included, averaged 84 percent of the speed at their second ventilatory threshold, slowing from 16.13 km/h on run 1 to 13.58 km/h on run 8. The authors concluded that sustaining a higher relative intensity appears central to a shorter running time.
One elite coach says the same. Tiago Lousa, who coaches 2024 world champion Alexander Rončević, told Red Bull in November 2025: “In sports like HYROX, 10Ks or half marathons, threshold training is probably the most important performance indicator.”
This part is our judgement, not a finding. A race that keeps you working hard for an hour or more, with runs held at or a little under threshold, rewards a higher threshold at least as much as a higher ceiling. In the simulated-race study, a higher VO2 max went with a faster finish; threshold was not measured there, so that study cannot say which matters more. Raise the pace you can hold for an hour and every run between the stations gets faster at the same effort.
Tempo runs, threshold repeats and intervals: what each adds
Tempo runs
One continuous block at threshold or just under. A review of how world-class distance runners train describes 20 to 50 minutes at about half-marathon pace, and notes the session should not be extremely fatiguing. Start nearer 15 to 20 minutes. A tempo run teaches you to hold one hard, even pace while it slowly gets harder, which is what a race run asks.
Threshold repeats
The same pace, broken into reps with short rests. Lousa's rule is that the rest is much shorter than the work: one to two minutes after a five or six minute rep, enough to reset without fully recovering. The review notes that repeats let you accumulate more time at threshold than one continuous run, and a 2023 paper on the Norwegian-style approach adds that threshold work may leave you fresher than harder intervals, so you can come back to it sooner. For most HYROX athletes this is the main hard run.
Intervals
Shorter, harder reps above threshold: 2 to 4 minutes at 3 km to 10 km race pace with 2 to 3 minutes of recovery, in the same review. They raise your ceiling, the top-end aerobic power that threshold sits under, and they cost the most recovery. The review calls them more specific to track racing than to the marathon, one reason to keep them the smaller share for a race lasting over an hour. They still belong: the authors of the simulated-race study recommend moderate-intensity endurance work and high-intensity intervals together. Lousa recommends doing VO2 max work on the SkiErg or rower, where the low impact keeps fatigue manageable.
Sample hard runs for early, middle and late in a build
Why threshold first and intervals later: in a 16-week trial, 60 well-trained male runners trained at the same load in four patterns. Those who did eight weeks leaning on threshold work, then eight weeks leaning on intervals, improved most, including about 1.5 percent off a 5 km time trial. Keeping either mix for 16 weeks, or the reverse order, did less. A 5 km is not a HYROX, but it is a controlled test of the order.
| When | Session | Where it comes from |
|---|---|---|
| Early | 4 x 5 minutes at threshold, 1 minute easy between | Lousa's reps of five to six minutes with one minute of rest |
| Early | 15 to 20 minute tempo run | A shortened version of the review's 20 to 50 minute threshold run |
| Middle | 3 x 10 to 12 minutes at threshold, 2 to 3 minutes easy between | Lousa's sets of 12 minutes with two to three minutes of rest |
| Middle | 5 or 6 x 1 km at threshold, 1 minute between | A shorter version of the 10 to 12 x 1,000 m elite session |
| Late | 5 x 3 minutes hard, 2 to 3 minutes easy jog between | The review's 2 to 4 minute intervals at 3 km to 10 km race pace |
| Late | 4 to 6 x 800 m to 1 km at about 5 km race effort, 2 to 3 minutes between | The review's 4 to 7 x 800 to 1,000 m |
- Run every threshold rep at the same pace. Add time before speed: more reps or longer reps first.
- Nearer the race, intervals take some of the hard-run slots rather than landing on top of them. With one hard run a week, alternate the two; keep threshold work going so the base does not fade.
- The last week or two belong to the taper. Keep a short interval session and cut its volume. More in tapering.
- Racing the relay? Each racer runs two runs of about 1 km, with a break between them unless the team puts them back to back. That is closer to an interval session than a long race, so intervals of around a kilometre carry more of your hard running, with threshold work under them. More in how the relay works.
Hard runs and bricks train different things
A threshold or interval run builds the engine; a brick trains starting it again on legs a station has just emptied. Count a hard brick as a hard day, keep it off the day before your hard run, and see compromised running for how to build bricks from short to race-like.
On a treadmill or a track
Treadmill
A treadmill suits threshold work: the belt holds the pace, so you learn what threshold feels like and cannot drift faster on the first rep. Set a 1 percent incline: nine trained male runners tested between about 10.5 and 18 km/h used the same energy at that grade as on the road. At the slow end of that range, a flat belt matched the road too.
Short intervals are harder. A belt takes several seconds to reach speed and to slow down, which eats into a two or three minute rep. Start the clock once the belt is at speed, or keep treadmill intervals to three minutes and longer.
Track and hills
A 400 m track makes 1 km reps simple: two and a half laps in lane 1. Aim for laps that match from the first rep to the last; laps that slow through the session mean you started too fast. Hills work too: Lousa recommends hill repeats for hard running, to protect the legs.
The harder runs in a Smash Coach plan
With a HYROX race on your plan, every week holds runs on their own, and your plan can also hold a tempo or interval run alongside your easy runs. Your coach writes and reworks your plan with Pro or during your trial. See Races and events.
Workout mode keeps the screen awake, a step with a time target counts down under TIME LEFT, and if you lock your phone the timer keeps going. With Say each exercise on and the app on screen, the voice says Halfway on timed work of a minute or more and counts you out with “Three. Two. One. Finished.” Tap NEXT after a timed run and the logging panel asks how far you got, so a treadmill rep goes in with its distance. See Train with workout mode.
Whatever plan you follow, the shape holds: most running easy, one hard run built mostly from threshold work, intervals nearer the race, and bricks on top. How running fits your week is in running for HYROX, where your race time goes is in getting faster, and sessions that mix runs with the stations are in HYROX workouts.