REF-1751 · Nguyen et al., 2026 · Journal of Strength and Conditioning Research, · Paper · PubMed

Recreational runners asked to run 1 km at RPE 3/10 picked nearly the same speed twice (ICC 0.93-0.97; smallest real change 0.7 km/h on a track and 1.6 km/h on a treadmill), but at the same rating they ran 20% slower on the treadmill than on the track (10% slower at RPE 8/10), in a within-runner reproducibility study of 55

Main caveat: One study of 55 recreational runners; sex split, fitness and experience not in the abstract.
limited evidenceMeasured on recreational to trained athletesRead from the abstract only

Nguyen and colleagues asked whether runners who set their own speed from a perceived-exertion target land on the same speed each time, and whether that speed is the same on a treadmill as on an indoor track. Fifty-five recreational runners completed six 1-km runs in randomised order: two at RPE 3/10 on each surface, and one at RPE 8/10 on each.

The speed chosen at RPE 3/10 repeated very closely on both surfaces (ICC 0.93-0.97); the error was smaller on the track (SEM 0.3 km/h, MDC 0.7 km/h) than on the treadmill (SEM 0.6 km/h, MDC 1.6 km/h). At the same rating, runners went 20% slower on the treadmill at 3/10 and 10% slower at 8/10.

At 3/10 on the treadmill, ground contact was 13% longer, flight time 35% shorter and step length 6% shorter, with similar trends at 8/10. The authors conclude that RPE is a reliable, practical tool for setting running intensity, and that treadmill and track call for context-specific use.

Participants

n = 55 recreational runners.
Not in the abstract: sex, age, training volume, running experience, treadmill familiarity, performance level.

Protocol

Six 1-km runs in randomised order: RPE 3/10 twice on an indoor track and twice on a treadmill; RPE 8/10 once on each.
Runners chose their own speed to match the rating; speed, heart rate and spatiotemporal variables (contact time, flight time, step length) were recorded.
Reliability: ICC, SEM and MDC on the repeated 3/10 runs; surface and rating differences tested at α = 0.05.
Not in the abstract: the RPE scale's anchors and how runners learned it, treadmill incline, rest between runs, number of sessions, how speed was set on the treadmill, heart-rate results, and absolute speeds.

Key Results

MeasureTrackTreadmill
ICC, speed at RPE 3/10 (repeat runs)0.93-0.97 (range across both surfaces)0.93-0.97 (range across both surfaces)
SEM0.3 km/h0.6 km/h
MDC0.7 km/h1.6 km/h
Treadmill vs track at the same ratingRPE 3/10RPE 8/10
Speed20% slower10% slower
Contact time+13%similar trend (no number)
Flight time−35%similar trend (no number)
Step length−6%similar trend (no number)
Reliability at RPE 8/10 was not assessed (one run per surface); heart-rate results are not in the abstract.

Practical Application

An easy run set by feel repeats well on the same surface, so RPE works as an easy-run prescription without a watch: at RPE 3/10 runners chose nearly the same speed twice (ICC 0.93-0.97). A change of less than about 0.7 km/h on a track, or 1.6 km/h on a treadmill, is inside the test's own noise.
Do not carry a pace between treadmill and track at the same effort: at the same rating runners ran 20% slower on the treadmill for easy running and 10% slower for hard running, with shorter steps and longer ground contact. Inference, not tested here: write treadmill sessions by RPE or time rather than by a pace taken from track or road running (the track was indoor; road running was not studied).
This supports [SYNTH-40], which treats perceived effort as an instrument for sessions without power and keeps threshold pace as a pace when the route allows; the treadmill-track gap adds that the pace that matches an effort depends on the surface.
Inference, not tested here: the authors suggest slower treadmill speed at the same effort may reduce joint loading for rehabilitation; loading was not measured, and the rating's reliability at hard efforts and over longer runs is untested.

Limitations

One study of 55 recreational runners; sex split, fitness and experience not in the abstract.
Reliability tested only at RPE 3/10 over 1 km; RPE 8/10 run once per surface.
Indoor track and treadmill only; outdoor road, terrain, heat and fatigue not studied.
Absolute speeds, heart-rate results, the RPE scale's anchors and treadmill settings (incline, familiarisation) are not in the abstract.
Written from the abstract and the PubMed record; full text not read, so funding and conflicts could not be checked.
How this entry was checked and changed
Why this level

a test reproducibility study of 55 (the rubric's B row for validation studies; below the 100 needed for B+ in a measurement study); no marker step, because the RPE-chosen speed is itself the subject