A Moderate-Intensity Interval Training Block Improves Endurance Performance in Well-Trained Cyclists
Participants
n=30 well-trained male cyclists, VO2max 70.5 ± 4.6 ml/kg/min. Each performed both conditions (randomized crossover).
Protocol
MIT block vs time-matched regular training (REG) in the general preparation phase:
| MIT block | REG (regular training) | |
|---|---|---|
| Duration | 7-day microcycle + 6-day active recovery period, then testing | time-matched |
| Interval sessions | 6 sessions in 7 days | regular preparatory routine, mostly low intensity; guideline: 2 MIT sessions, or 1 MIT + 1 HIT session, per week |
| Format | 5-7 × 10-14 min work intervals | — |
| Intensity (RPE) | prescribed 14-15 (Borg 6-20); achieved 14.4 ± 0.3 | — |
| % PO-VO2max | 66 ± 5% | — |
| % HRmax | 85 ± 3% | — |
| Lactate | 2.8 ± 1.1 mmol/L | — |
| TRIMP | 1944 ± 436 | 1800 ± 232 (P = 0.27, not different) |
Key point: intensity = moderate, not high: 66% of power at VO2max, 85% HRmax, lactate 2.8 mmol/L. Interval work per session 50-98 min (5-7 × 10-14 min, arithmetic).
Key Findings
| Measure | MIT block | REG | p-value |
|---|---|---|---|
| PO4mmol | +4.0 ± 4.4% | -1.3 ± 3.7% | p<0.01 |
| PO-VO2max (1-min peak in incremental test) | +2.5 ± 4.5% | -0.7 ± 3.9% | p<0.01 |
| VO2max | +2.0 ± 3.9% | 0.0 ± 3.5% | p=0.05 |
| PO15min | +3.9 ± 8.3% | +0.2 ± 6.8% | p=0.14 (ns) |
Primary result: with the same training impulse (TRIMP not different), the MIT block improved power at 4 mmol/L, peak incremental power and VO2max more than regular training in cyclists with VO2max 70.5.
Comparison with a HIT block
Not from this paper: the same group later compared a one-week MIT block with a one-week HIT block directly in a crossover of 22 well-trained cyclists — see REF-421 (Rønnestad 2025): both blocks raised 15-min power with no difference between them; the MIT block gained more at 4 mmol/L, the HIT block tended to protect sprint power. The MIT block there used the same 6-sessions-in-7-days, 5-7 × 10-14 min format.
Mechanism
Inference, not tested in this paper: six sessions of long, moderate intervals in seven days concentrate a large volume of work near the first-to-second-threshold range at low lactate, followed by six days of recovery — the block principle at a moderate intensity. The abstract reports outcomes only; no signalling, recovery or fatigue markers.
Practical Application
Limitations
Only males. VO2max 70.5 ml/kg/min — transfer to less trained riders not tested. PO15min did not reach significance (p=0.14). Single MIT prescription (RPE 14-15) — other RPE targets not tested. General preparation phase only. Crossover with a time-matched control period; no long-term follow-up.
How this entry was checked and changed
regraded 2026-09-27 from A: crossover, n=30