REF-1451 · Billat et al., 2004 · Pflügers Archiv European Journal of Physiology · Paper · PubMed

What does training at MLSS speed change?

11 veteran male runners, 6 weeks, no control: time to exhaustion at that speed went 44 to 63 min while the speed rose only a little. Training dose unknown; abstract only.

Main caveat: Uncontrolled; learning, motivation and test variation are confounded with training.
limited, mixed evidenceMeasured on trained athletes

Billat and colleagues tested 11 veteran male long-distance runners before and after 6 weeks of training at MLSS velocity (MLSSv).

Three tests were used: an incremental test for VO2max and the velocity at the lactate threshold (vLT); a submaximal test of two 20-min stages at 95 and 105% of vLT, separated by 40 min, to determine MLSSv and its lactate; and a time-to-exhaustion run at MLSSv. Duration at MLSSv went from 44 ± 10 to 63 ± 12 min and distance from 10.4 to 15.7 km (P < 0.01).

MLSSv rose significantly, its fraction of VO2max stayed the same (85.2 ± 4.5 vs 85.3 ± 5.2%, P = 0.93), lactate at MLSS did not change, and about 80% of energy came from carbohydrate. The authors conclude that training at MLSS brings small rises in MLSSv and VO2max but substantially enhances time to exhaustion (+50%).

Our reading: suggestive for "time at intensity grows before the line moves".

Three cautions: the +50% fits the distance (10.4 to 15.7 km, +51%), while the time went up 43% (our arithmetic); average speed in those runs rose about 5%, from about 14.2 to 15.0 km/h (our arithmetic), which is not nothing; and with no control group, familiarity with a long run to exhaustion and test variability cannot be separated from training.

Protocol

Participants: n = 11 male veteran long-distance runners (ages and VO2max values not in the abstract).
Training: 6 weeks at MLSSv; sessions a week, session length and total time at MLSS not in the abstract.
Tests: incremental test; two 20-min stages at 95% and 105% of vLT with 40 min rest, used to determine MLSSv (a two-stage determination rather than a series of constant-load trials); time-to-exhaustion run at MLSSv with substrate balance calculated.
Funding and interests: PubMed lists "Research Support, Non-U.S. Gov't" without naming the funder; no conflict statement in the record.

Key Results

OutcomeBeforeAfterP
Time to exhaustion at MLSSv (min)44 ± 1063 ± 12< 0.01
Distance at MLSSv (km)10.415.7< 0.01
MLSSv as % of VO2max85.2 ± 4.585.3 ± 5.20.93
MLSSvnot givenrose "significantly"not given
VO2maxnot given"small" increasenot given
Lactate at MLSSnot givenunaffectednot given
Energy from carbohydrate in the runabout 80%about 80%unchanged
Individual response: not reported; no control arm to compare a spread with.

Mechanisms

Measured: longer time to exhaustion, unchanged fractional use of VO2max at MLSSv, unchanged carbohydrate share.
Authors' interpretation: training at MLSS enhances endurance at that speed much more than it moves the speed; carbohydrate remains the major substrate in an exhaustive run of about 1 h.
Inference: post-training runs were apparently at the new, faster MLSSv, so the longer duration came at a higher speed; the abstract does not spell this out. Whether the same holds below MLSS is untested.

Practical Application

What does training at MLSS speed change? 11 veteran male runners, 6 weeks, no control: time to exhaustion at that speed went 44 to 63 min while the speed rose only a little. Training dose unknown; abstract only.
Progression: suggestive, not proof, for building duration before intensity. No trial here or elsewhere in the base compares the two. Not from this paper; the base's own practice: a rep ladder such as 4 × 10 to 2 × 20 min (SYNTH-27), judged by feel and lactate (REF-137) and by heart-rate drift (SYNTH-27).
Time at this intensity is finite: 44 min before training here; compare REF-1432 (B+) at MLSS, REF-747 (B) at FTP, REF-750 (B) at critical power. A hold to exhaustion is a test, not a routine session (the base's own practice, not from this paper).
What it does not show: what happens with work below MLSS, that this stimulus raises the threshold more than intervals, anything in women, cyclists or younger runners. It tested no sweet-spot format.

Limitations

Uncontrolled; learning, motivation and test variation are confounded with training.
Abstract only; closed access. Training dose, ages and most absolute values missing.
Small, male, masters; n = 11.
MLSS by two stages of 20 min, not repeated constant-load trials to confirm a steady state (from the abstract's description).
The printed "+50%" matches distance rather than time.
Funding: non-US government support per PubMed, funder not named in the record.
How this entry was checked and changed
Why this level

(from the abstract) — the rubric's B design (uncontrolled pre-post) with a limit beyond design: an abstract-only small study whose key method, the training dose, is missing, and whose main outcome is time to exhaustion with no control group or reliability figure