REF-421 · Rønnestad et al., 2025 · European Journal of Sport Science, Nov 2025; · Paper · PubMed · Free full text
Block Training With Moderate- or High-Intensity Intervals Both Improve Endurance Performance in Well-Trained Cyclists
One-week MIT block vs one-week HIT block, crossover in 22 cyclists: 15-min power +4.9% vs +2.8% (no difference), MIT gains more at 4 mmol/L (+4.5% vs +2.1%), HIT tends to protect sprint power
Participants
n=22 well-trained cyclists (21 men, 1 woman), VO2max 69.5 (6.0) ml/kg/min.
Protocol — Crossover design
Each cyclist performed BOTH a MIT block and a HIT block, separated by 2 months. Post-testing after 6 days of active recovery.
MIT block: 6 sessions over 7 days; 5-7 × 10-14-min work intervals; RPE 14.5 (0.3).
HIT block: 5 sessions over 6 days; 5 × 8.75-min intervals each made of multiple short work bouts; RPE 17.1 (0.4).
Tests: 15-min maximal cycling power (PO15min), 10-s maximal sprint power (PO10sec), power at 4 mmol/L blood lactate (PO4mmol), VO2max, gross efficiency, %VO2max at PO4mmol.
Key Findings
| Measure | MIT block | HIT block | Between blocks |
|---|---|---|---|
| PO15min | +4.9 (8.7)% | +2.8 (5.3)% | no difference (p = 0.44) |
| PO4mmol | +4.5 (4.5)% | +2.1 (2.7)% | MIT greater (p = 0.03, moderate ES) |
| PO10sec | −1.5 (7.3)% | +1.5 (3.7)% | moderate ES for HIT, not significant (p = 0.08) |
| VO2max | — | — | no difference (p = 0.43) |
| Gross efficiency | — | — | no difference (p range 0.43-0.79) |
| %VO2max at PO4mmol | +1.2 (3.4) %-points | −0.9 (2.5) %-points | MIT greater (p = 0.02, moderate ES) |
Both blocks improved PO15min; the two were not different.
MIT (lower intensity, longer work) produced the larger threshold gain (PO4mmol and %VO2max at PO4mmol); HIT (higher intensity, shorter work) tended to preserve 10-s sprint power while MIT tended to lose some.
Authors' conclusion: both a MIT block and a HIT block can improve endurance-performance determinants and PO15min, with some work-intensity-specific adaptations.
Practical Application
In 22 well-trained cyclists (VO2max 69.5), a one-week MIT block (6 sessions in 7 days, 5-7 × 10-14 min at RPE 14.5) and a one-week HIT block (5 sessions in 6 days, 5 × 8.75 min of short intervals at RPE 17.1), done 2 months apart and tested after 6 days of active recovery, both raised 15-min power (+4.9% vs +2.8%, no difference between blocks); MIT gained more at 4 mmol/L lactate (+4.5% vs +2.1%) and in %VO2max at that power, HIT tended to hold sprint power better (+1.5% vs −1.5%, not significant), and VO2max and efficiency changed no differently. So a one-week block works at either intensity; choose it by the adaptation you want — MIT for threshold power, HIT if sprint power must not slip.
Inference, not tested: the MIT block's threshold gain came with a small loss of 10-s power in this sample; a rider with a sprint-dependent race soon after a MIT block should keep a few short maximal efforts in the week.
Limitations
n=22, 21 men and 1 woman; female response essentially untested.
Well-trained cohort (VO2max 69.5); transfer to amateur level not tested.
One MIT format and one HIT format only; other formats (long-interval HIT, sweet-spot) were not compared.
Two-month washout assumed sufficient in a within-subject design; the order was fixed (MIT first), so order and season effects cannot be separated from the block contrast (corrected 2026-10-12, full text).
Performance outcome is a 15-min maximal effort plus lab determinants, not a race.
Group-level changes carry large standard deviations (e.g., PO15min +4.9 (8.7)%): individual responses vary widely.
How this entry was checked and changed
Why this level
regraded 2026-09-27 from A: controlled crossover, n=22
Content correction 2026-09-27
The whole "%VO2max-fraction is HIT-specific" story (ΔVO2max correlated with %VO2max and time ≥90% VO2max in HIT, ~55% of variance explained, no such relationship in MIT; VO2 measured in session #2) -> not in the abstract; removed together with the mechanism section built on it. Title changed to the paper's own.
"Age ≈19", "HR 86 ± 4% / 90 ± 3% HRmax", "lactate 2.9 ± 0.8 / 7.5 ± 1.5 mmol/L", "30 s at ~118% / 15 s at ~60% with 3 min between", "2-4 min recovery", "RPE 14-15 / 16-18" -> not in the abstract; replaced by the abstract's RPE 14.5 (0.3) and 17.1 (0.4) and "5 × 8.75-min with multiple short intervals".
Results table "VO2max improved, P4mmol improved, 15-min TT improved (magnitude not the focus)" -> the abstract's numbers: PO15min +4.9% vs +2.8% (p = 0.44), PO4mmol +4.5% vs +2.1% (p = 0.03), PO10sec +1.5% vs −1.5% (p = 0.08), no VO2max/GE difference, %VO2max at PO4mmol +1.2 vs −0.9 points (p = 0.02).
House prescriptions ("target ≥5-10 min >90% VO2max", "50-100 min/session", "lactate 2.5-3.3", "race power 70-85% FTP") -> removed. Level A -> B+ (crossover n=22); Tier 3 and Sport lines added.
Cross-references to duplicate stubs repointed to their canonical entries (REF-085->REF-303); the stubs were emptied on 2026-09-27.
Full text (checked 2026-10-12)
Correction: the entry says "order counterbalanced", but the paper used a fixed sequence of interventions "with the MIT block preceding the HIT block", with 55.1 (16.5) days of regular training between blocks (full text).
Participants were aged 19.2 (3.6) years with 4.4 (2.7) years of competitive history, classed as performance level 3 (n = 3), 4 (n = 8) and 5 (n = 11); 43 volunteered and 21 withdrew, 8 of them due to respiratory tract infections (full text).
MIT sessions (3 days on, 1 rest day, 3 days on; RPE 14–15) were 7 × 10-min work intervals with 2.5-min recoveries, 6 × 12-min with 3-min recoveries, and 5 × 14-min with 3.5-min recoveries (full text).
HIT sessions were 5 × 8.75-min work intervals of 30 s at ∼118% of 40-min maximal sustainable power output and 15 s at ∼60%, at RPE 16–18 with 3-min recoveries; total work interval duration was 7 h and 4 min (MIT) versus 3 h and 42 min (HIT) (full text).
Average session load was 85.5% of HRmax, 78.1% of VO2max and 2.9 mmol·L−1 lactate in MIT versus 90.0% of HRmax, 83.4% of VO2max and 7.5 mmol·L−1 in HIT, with time ≥ 90% of VO2max of 04:44 versus 10:39 (m:s) (full text, Table 1).
The 6-day recovery was: day 1 complete rest; day 2 rest or 20–40 min low intensity; day 3 0.5–1.5 h low intensity; day 4 20 min low intensity plus 2 × 5-min MIT and one 1-min progressive high-intensity interval; day 5 rest; day 6 2 × 5-min MIT plus 3 × 1-min HIT (full text).
VO2max increased within the HIT block (1.7 (2.8) mL·min−1·kg−1; p < 0.01) but not the MIT block (p = 0.06), and peak knee-extension torque at 60°·s−1 fell after MIT (2.78 to 2.63 Nm·kg−1) with a block difference (p = 0.02) (full text, Table 3).