REF-194 · Rønnestad et al., 2020b · International Journal of Sports Physiology and Performance · Paper · PubMed

A fast start (1.5 min at 100%, then 3.5 min at 85% of maximal aerobic speed) raised mean VO₂ across 5 × 5-min intervals only slightly

87.6% vs 86.1% of VO₂peak — at the same mean speed and a slightly lower RPE, in eleven well-trained skiers

Blimited evidenceMeasured on highly trained athletesWritten before October 2026, being re-checked

Protocol

Eleven well-trained cross-country skiers performed two roller-ski skating sessions in randomised order, each 5 × 5-min work intervals with 3-min relief. TRAD: constant speed at 90% of maximal aerobic speed. DEC: each interval 1.5 min at 100% of maximal aerobic speed, then 3.5 min at 85% — the same mean speed.

Key Results

Mean VO₂ across all work intervals: 87.6% (DEC) vs 86.1% (TRAD) of VO₂peak (P < .05) — about 1.5 percentage points.
Peak VO₂ during the intervals: 98.2% vs 95.4% of VO₂peak (P < .05).
Session RPE was LOWER after the fast-start session: 16.1 vs 16.5 (P < .05).
No differences in mean heart rate, blood lactate or leg-press peak power.

Practical Application

A fast start buys a little more oxygen uptake at the same average speed, and it does not feel harder. Opening each rep above the target and settling below it raised mean VO₂ by ~1.5 percentage points of VO₂peak and peak VO₂ by ~3, with a slightly lower RPE.
Treat it as a refinement, not a new stimulus. The difference is small; use it when the aim of the session is time near VO₂max, not as a reason to rebuild a working interval programme.
Heart rate and lactate did not separate the two sessions, so neither tells the athlete which version they rode — the power or speed profile does.

Limitations

n = 11, one acute session per condition; no training study, so the long-term effect of fast-start intervals is not tested here.
Roller-ski skating; cycling and running evidence for fast starts is separate.
The effect is small (about 1.5 points of VO₂peak on average) and individual variation is not reported in the abstract.
Re-entered from the abstract after the earlier table was found not to match it; the full text has not been re-read.
How this entry was checked and changed
Why this level

regraded 2026-09-26 from B+: crossover, n=11

Content correction 2026-09-26

Until today this entry carried a Key Results table that did not match the paper: mean VO₂ 91% vs 96% of VO₂max, 6.2 vs 8.8 min above 90% (+42%), an 18% larger VO₂ area, faster kinetics and a 6-beat higher heart rate. The abstract reports a mean of 87.6% vs 86.1% of VO₂peak across the work intervals and NO difference in heart rate.

The table, the mechanism section built on it and the cross-reference descriptions (which named the wrong studies) were removed; everything below is from the abstract.