REF-1002 · Stepto et al., 1999 · Medicine & Science in Sports & Exercise, Vol. · Paper · PubMed

Effects of different interval-training programs on cycling time-trial performance

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

Twenty male endurance cyclists did a 25-kJ sprint test, an incremental peak aerobic power (PP) test and a 40-km time-trial simulation, then were randomised to one of five interval sessions of differing intensity. On top of their normal aerobic base work they did 6 of these sessions in 3 wk, then repeated the tests.

Time-trial improvement (%) was modelled as a polynomial of the intensity rank; the cubic trend was strong and significant, with the largest predicted gains for intervals at 85% PP and at 175% PP. Neither 100% PP nor 80% PP intervals improved performance significantly.

Participants

20 male endurance cyclists (peak oxygen uptake 4.8 ± 0.6 L·min⁻¹, mean ± SD), randomly assigned to five interval types. Group sizes are not stated in the abstract.

Protocol

Five interval sessions: 12 × 30 s at 175% PP, 12 × 60 s at 100% PP, 12 × 2 min at 90% PP, 8 × 4 min at 85% PP, or 4 × 8 min at 80% PP. Recoveries are not given in the abstract.
6 sessions over 3 wk, in addition to usual aerobic base training.
Tests before and after: 25-kJ sprint test, incremental test (PP), simulated 40-km time trial on a Kingcycle ergometer.
Analysis: percent improvement modelled as a polynomial function of the rank order of interval intensity (procedure validated by simulation).

Key Results

Time-trial performance was highly reliable when controlled for training effects (coefficient of variation = 1.1%).
Cubic trend strong and statistically significant (overall correlation = 0.70, P = 0.005).
Largest predicted gains: 2.8% for 85% PP intervals (95% CI = 4.3-1.3%) and 2.4% for 175% PP intervals (95% CI = 4.0-0.7%).
Neither the 100% PP nor the 80% PP intervals gave a statistically significant improvement.
Quadratic and linear trends were weak or insubstantial. No result is stated in the abstract for the 90% PP intervals.
Authors' conclusion: work bouts close to race-pace enhance 1-h endurance performance; much higher intensity bouts also appear to improve performance, possibly by a different mechanism.

Practical Application

"Three weeks before a 40-km time trial, which intervals?" In 20 male endurance cyclists randomised across five interval intensities, 6 sessions over 3 wk on top of base training (between-group comparison, no control, gains predicted from a fitted curve), the largest 40-km improvements were for 8 × 4 min at 85% of peak power (2.8%) and 12 × 30 s at 175% (2.4%); intervals at 100% and at 80% of peak power gave no significant gain. The authors read the 85% result as "close to race-pace".
This is the base's one trial bearing on "close to the event, train at the event's intensity" — and it is thin: twenty riders across five groups, and the figures come from a polynomial model, not from group means.
What was not tested: a control group, a block aimed at a diagnosed limiter, any event other than a 40-km time trial.
The supramaximal 30-s result matches the later finding in highly trained cyclists (REF-999) that this format also improves a 40-km time trial.
Not from this paper; the base's own practice: where sprint formats belong is SYNTH-46.

Limitations

n=20 across five groups; no control group.
Reported improvements are predictions from a cubic model over rank-ordered intensity, with wide confidence intervals.
Six sessions in 3 wk; no follow-up. Interval formats differ in duration and number as well as intensity.
Men only; simulated time trial on an ergometer.
Written from the abstract and record metadata only (full text not read).
How this entry was checked and changed
Why this level

randomised, but n=20 spread over five groups; the reported gains are model predictions