REF-991 · Rosenblat et al., 2025 · Sports Medicine, Vol. · Paper · PubMed

Which Training Intensity Distribution Intervention will Produce the Greatest Improvements in Maximal Oxygen Uptake and Time-Trial Performance in Endurance Athletes? A Systematic Review and Network Meta-analysis of Individual Participant Data

A-fairly strong evidenceMeasured on trained to highly trained athletesWritten before October 2026, being re-checked

This systematic review ran a network meta-analysis on individual participant data to compare training intensity distribution (TID) models for VO2max and for time-trial (TT) performance among endurance-trained athletes.

Eligible studies were experimental or quasi-experimental, enrolled trained endurance athletes, set a polarized (POL) programme against a comparator with a different TID, and let time in each intensity domain be quantified.

Thirteen studies were included, with 348 athletes (296 male, 52 female; 150 recreational, 198 competitive); across studies, mean age was between 17.6 and 41.5 years and VO2max between 46.6 and 68.3 mL·kg-1·min-1.

Using time in heart-rate zones, POL and pyramidal (PYR) programmes did not differ for VO2max (SMD = -0.06, p = 0.68) or for TT performance (SMD = -0.05, p = 0.34), and POL did not differ significantly from any other TID.

In a subgroup analysis, recreational and competitive athletes responded differently in VO2max to POL versus PYR (SMD = -0.63, p < 0.05): competitive athletes may gain more VO2max with POL, recreational athletes with PYR.

Participants

348 athletes from 13 studies: 296 male and 52 female; 198 competitive and 150 recreational endurance athletes. Across studies, mean age was between 17.6 and 41.5 years and VO2max between 46.6 and 68.3 mL·kg-1·min-1. Sports are not given in the abstract.

Protocol

Sources: Medline and SPORTDiscus, from inception until 11 February 2024.
Inclusion: peer-reviewed, English, experimental or quasi-experimental, trained endurance athletes, a POL intervention compared with a different TID model, duration in each intensity domain quantifiable, VO2max or TT performance reported.
Analysis: network meta-analysis of individual participant data; TID classified by the time-in-heart-rate-zone approach; subgroup analysis by performance level (recreational vs competitive).
Comparison: between groups assigned to different distributions.

Key Results

Main result — POL vs PYR: VO2max did not differ (SMD = -0.06, p = 0.68), and neither did TT performance (SMD = -0.05, p = 0.34).
POL did not differ significantly from any other TID intervention.
Subgroup result — recreational and competitive athletes differed significantly in how their VO2max responded to POL vs PYR (SMD = -0.63, p < 0.05). POL may suit competitive athletes better for VO2max gains, whereas PYR may suit recreational athletes better.
No subgroup difference for TT performance is reported in the abstract.
Authors' conclusion: the VO2max adaptations following different TID interventions depend on performance level.

Practical Application

**"Polarized or pyramidal — which raises VO2max and time-trial performance more?" In a network meta-analysis of individual data from 13 studies (348 trained endurance athletes: 150 recreational, 198 competitive; between-group comparison), there was no difference between polarized and pyramidal for VO2max (SMD = -0.06) or time trial (SMD = -0.05).In a subgroup analysis the VO2max response differed by level (SMD = -0.63, p < 0.05): competitive athletes may gain more with polarized, recreational athletes with pyramidal.** For a recreational athlete this is evidence against assuming the more high-intensity-weighted distribution is the better route to a higher VO2max.
Weight the two results differently. The null main result is the primary finding. The level difference is a subgroup analysis, worded "may" by the authors, and concerns VO2max only.
The abstract does not define pyramidal and polarized in percentages, nor the line between recreational and competitive. Not from this paper; the base's own shorthand: pyramidal carries more moderate (between-threshold) work than high-intensity work, polarized the reverse.
Classification was by time in heart-rate zone. Not from this paper: counted that way, a nominally polarized programme can look pyramidal (REF-467), so the labels are less far apart than they sound.

Limitations

The performance-level finding is a subgroup analysis; the authors hedge it ("may") and report it for VO2max only.
13 studies, 348 athletes; includes quasi-experimental designs; 52 women.
How recreational and competitive were defined, the intervention durations and the sports are not given in the abstract.
TID was classified by time in heart-rate zone; other counting methods can relabel the same training.
Every included study had a polarized arm, so comparisons among non-polarized distributions are indirect.
English-language, two databases.
Written from the abstract and record metadata only (full text not read).
How this entry was checked and changed
Why this level

the MAIN result (no difference between distributions) is a network meta-analysis of 13 studies, n = 348; the performance-level finding is a SUBGROUP result and carries less weight than the level suggests

Content correction 2026-09-27
2026-10-02: aligned with the rewritten SYNTH-42 (missing stimulus, one lever per block, level C+): cross-reference description — the quoted old default replaced with "a caveat to the starting bet".