REF-999 · Laursen et al., 2002 · Medicine & Science in Sports & Exercise, Vol. · Paper · PubMed

Interval training program optimization in highly trained endurance cyclists

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

Thirty-eight highly trained cyclists and triathletes were tested before and after 2 and 4 wk of training: a progressive test for VO2peak and peak aerobic power output (PPO), a time to exhaustion test (Tmax) at the VO2peak power output (Pmax), and a 40-km time trial. They were matched and assigned to three high-intensity interval training (HIT) groups or a control group.

The HIT groups trained HIT twice per week while all athletes kept their regular low-intensity training. All three HIT groups improved 40-km time-trial performance and PPO significantly more than control, and the two groups whose intervals were at Pmax improved VO2peak significantly more than control.

Participants

38 cyclists and triathletes (mean ± SD: age 25 ± 6 yr; mass 75 ± 7 kg; VO2peak 64.5 ± 5.2 mL·kg⁻¹·min⁻¹), matched and assigned to four groups (N = 8, 9, 10 and 11).

Protocol

Group 1 (N = 8): 8 × 60% Tmax at Pmax, 1:2 work:recovery ratio.
Group 2 (N = 9): 8 × 60% Tmax at Pmax, recovery at 65% HRmax.
Group 3 (N = 10): 12 × 30 s at 175% PPO, 4.5-min recovery.
Control (N = 11): no HIT.
HIT twice per week; all athletes maintained their regular low-intensity training throughout.
Tests before, and after 2 and 4 wk. (The abstract labels the first two groups both "G2"; the results text identifies them as G1 and G2.)

Key Results

40-km time trial: all HIT groups improved (+4.4 to +5.8%) significantly more than control (-0.9 to +1.1%; P < 0.05).
Peak power output: HIT groups +3.0 to +6.2%, significantly more than control (same control range and P value as reported in the abstract's combined statement).
VO2peak: G1 (+5.4%) and G2 (+8.1%) improved significantly more than control (+1.0%; P < 0.05). No such statement is made for G3.
The abstract gives no separate results for the 2-wk test and no comparison between the HIT groups.

Practical Application

"I am already highly trained — will adding intervals still make me faster, and how soon?" In 38 highly trained cyclists and triathletes (VO2peak 64.5) matched into four groups (between-group comparison with a control), HIT twice per week on top of regular low-intensity training improved 40-km time-trial performance by +4.4 to +5.8% versus -0.9 to +1.1% in controls, with all three interval regimens working. The two regimens at VO2peak power also raised VO2peak (+5.4% and +8.1% versus +1.0%).
The sprint regimen (12 × 30 s at 175% PPO) improved the 40-km time trial as well, although the abstract reports no VO2peak advantage over control for it — performance moved without a reported engine gain.
What the trial does not show: that the athletes had stalled before it, which regimen is superior, or what happens beyond 4 wk.
Inference, not tested here: a measurable change within 4 wk in trained cyclists is compatible with reviewing a block at about that point.
Not from this paper; the base's own practice: interval shape is SYNTH-33.

Limitations

Matched, not randomised; 8 to 11 per group.
The control group did no added work, so the HIT groups differ from it in both intensity and total load.
Only ranges across groups are given for time-trial and peak-power changes; no between-regimen statistics and no 2-wk results in the abstract.
4 wk only; no follow-up.
Written from the abstract and record metadata only (full text not read).
How this entry was checked and changed
Why this level

matched rather than randomised allocation, n=38 with 8 to 11 per group