NCT07565168

Brief Summary

This study aims to compare the effects of three different training intensity distribution (TID) models-polarized, threshold, and pyramidal-on physiological and performance adaptations in recreational distance runners. Twenty-four participants were assigned to one of the three training interventions and completed an 8-week structured running program based on the respective TID approach. The primary objective is to determine whether different TID models elicit distinct changes in key physiological markers and endurance performance. The study seeks to answer whether a specific intensity distribution strategy provides superior adaptations in recreational runners when training is prescribed over a controlled intervention period.

Trial Health

87
On Track

Trial Health Score

Automated assessment based on enrollment pace, timeline, and geographic reach

Enrollment
24

participants targeted

Target at below P25 for not_applicable

Timeline
Completed

Started Apr 2024

Typical duration for not_applicable

Geographic Reach
1 country

1 active site

Status
completed

Health score is calculated from publicly available data and should be used for screening purposes only.

Trial Relationships

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Study Timeline

Key milestones and dates

Study Start

First participant enrolled

April 1, 2024

Completed
4 months until next milestone

Primary Completion

Last participant's last visit for primary outcome

July 30, 2024

Completed
1.7 years until next milestone

Study Completion

Last participant's last visit for all outcomes

April 20, 2026

Completed
7 days until next milestone

First Submitted

Initial submission to the registry

April 27, 2026

Completed
7 days until next milestone

First Posted

Study publicly available on registry

May 4, 2026

Completed
Last Updated

May 4, 2026

Status Verified

April 1, 2026

Enrollment Period

4 months

First QC Date

April 27, 2026

Last Update Submit

April 27, 2026

Conditions

Aerobic PerformanceEndurance Training Adaptations in RunnersTraining Intensity Distribution (TID)

Keywords

Running performanceEndurance trainingTime Trial

Outcome Measures

Primary Outcomes (4)

  • Maximal Oxygen Uptake (VO₂max)

    Assessment of changes in maximal oxygen uptake (VO₂max) obtained during an incremental exercise test. VO₂max is used as a measure of maximal aerobic capacity and cardiorespiratory fitness.

    Baseline to 8 weeks

  • Ventilatory Thresholds and Associated Running Speeds

    Assessment of changes in the first and second ventilatory thresholds (VT1 and VT2) and their corresponding running speeds, determined during an incremental exercise test. These variables reflect submaximal endurance capacity and physiological determinants of performance and their changes after intervention.

    Baseline to 8 weeks

  • Running Economy

    Assessment of changes in running economy, defined as the oxygen cost of running at a standardized submaximal speed during laboratory testing. This measure reflects the efficiency of movement during endurance exercise.

    Baseline to 8 weeks

  • Changes in 5-km time trial performance

    Assessment of changes in endurance performance measured as completion time in a 5-km time trial conducted under standardized conditions. Pre- to post-intervention differences are used to evaluate the effect of the training interventions on real-world running performance.

    Baseline to 8 weeks

Study Arms (3)

Polarized training Intensity Distribution

EXPERIMENTAL

Participants assigned to the polarized training group perform an 8-week structured endurance training program characterized by a high proportion of low-intensity exercise and a smaller proportion of high-intensity exercise, with minimal time spent at moderate intensities. Training intensity is prescribed using an individualized five-zone model based on baseline physiological assessments. The majority of training is performed in the lowest intensity zones (Zones 1-2), while high-intensity sessions are conducted in the highest zones (Zones 4-5). Training load and adherence are monitored using GPS-enabled sport watches.

Other: Polarided training intensity distribution

Threshold Training Intensity Distribution

EXPERIMENTAL

Participants assigned to the threshold training group complete an 8-week structured endurance training program emphasizing a greater proportion of training at moderate-to-high intensities, particularly around the second ventilatory threshold. Training intensity is prescribed using an individualized five-zone model derived from baseline physiological assessments. A substantial portion of training is performed in intermediate zones (Zones 3-4), with comparatively less time spent at low (Zones 1-2) and high intensities (Zone 5). Training sessions are monitored via GPS-enabled sport watches to ensure adherence.

Other: Threshold Training Intensity Distribution

Pyramidal training Intensity Distribution

EXPERIMENTAL

Participants assigned to the pyramidal training group perform an 8-week structured endurance training program characterized by a progressive decrease in training volume from low to high intensities. Training intensity is prescribed using an individualized five-zone model based on baseline physiological assessments. Most training is accumulated in low-intensity zones (Zones 1-2), with moderate amounts in intermediate zones (Zone 3) and smaller proportions at higher intensities (Zones 4-5), forming a pyramidal distribution. Training load and compliance are monitored using GPS-enabled sport watches.

Other: Pyramidal Training Intensity Distribution

Interventions

Polarided training intensity distributionOTHER

This intervention consists of an endurance training program based on a polarized intensity distribution model. Training intensity is prescribed using an individualized five-zone system derived from physiological assessments (e.g., ventilatory thresholds and maximal oxygen uptake). The model is characterized by a high proportion of training performed at low intensities (Zones 1-2) and a smaller but meaningful proportion at high intensities (Zones 4-5), with minimal time accumulated at moderate intensities (Zone 3). This distribution aims to maximize adaptations by combining extensive low-intensity volume with targeted high-intensity stimuli.

Also known as: POL
Polarized training Intensity Distribution
Threshold Training Intensity DistributionOTHER

Participants assigned to the threshold training group complete an 8-week structured endurance training program emphasizing a greater proportion of training at moderate-to-high intensities, particularly around the second ventilatory threshold. Training intensity is prescribed using an individualized five-zone model derived from baseline physiological assessments. A substantial portion of training is performed in intermediate zones (Zones 3-4), with comparatively less time spent at low (Zones 1-2) and high intensities (Zone 5). Training sessions are monitored via GPS-enabled sport watches to ensure adherence.

Also known as: THR
Threshold Training Intensity Distribution
Pyramidal Training Intensity DistributionOTHER

Participants assigned to the pyramidal training group perform an 8-week structured endurance training program characterized by a progressive decrease in training volume from low to high intensities. Training intensity is prescribed using an individualized five-zone model based on baseline physiological assessments. Most training is accumulated in low-intensity zones (Zones 1-2), with moderate amounts in intermediate zones (Zone 3) and smaller proportions at higher intensities (Zones 4-5), forming a pyramidal distribution. Training load and compliance are monitored using GPS-enabled sport watches.

Also known as: Pyr
Pyramidal training Intensity Distribution

Eligibility Criteria

Age18 Years - 60 Years
Sexall
Healthy VolunteersYes
Age GroupsAdult (18-64)

You may qualify if:

  • age ≥ 18 years;
  • a habitual training frequency of ≥ 4 sessions·week
  • running experience ≥ 2 years;
  • absence of musculoskeletal injuries in the preceding 3 months

You may not qualify if:

  • an official 10-km race time \> 40:00 min:s for men and \> 50:00 min:s for women
  • any cardiometabolic disease

Contact the study team to confirm eligibility.

Sponsors & Collaborators

Study Sites (1)

Cam. del Molino, 5, Fuenlabrada, Madrid

Fuenlabrada, Madrid, 28943, Spain

Location

Related Publications (6)

  • Munoz I, Seiler S, Bautista J, Espana J, Larumbe E, Esteve-Lanao J. Does polarized training improve performance in recreational runners? Int J Sports Physiol Perform. 2014 Mar;9(2):265-72. doi: 10.1123/ijspp.2012-0350. Epub 2013 May 22.

    PMID: 23752040BACKGROUND

  • Casado A, Gonzalez-Mohino F, Gonzalez-Rave JM, Foster C. Training Periodization, Methods, Intensity Distribution, and Volume in Highly Trained and Elite Distance Runners: A Systematic Review. Int J Sports Physiol Perform. 2022 Jun 1;17(6):820-833. doi: 10.1123/ijspp.2021-0435. Epub 2022 Apr 13.

    PMID: 35418513BACKGROUND

  • Filipas L, Bonato M, Gallo G, Codella R. Effects of 16 weeks of pyramidal and polarized training intensity distributions in well-trained endurance runners. Scand J Med Sci Sports. 2022 Mar;32(3):498-511. doi: 10.1111/sms.14101. Epub 2021 Nov 25.

    PMID: 34792817BACKGROUND

  • Seiler KS, Kjerland GO. Quantifying training intensity distribution in elite endurance athletes: is there evidence for an "optimal" distribution? Scand J Med Sci Sports. 2006 Feb;16(1):49-56. doi: 10.1111/j.1600-0838.2004.00418.x.

    PMID: 16430681BACKGROUND

  • Seiler S. What is best practice for training intensity and duration distribution in endurance athletes? Int J Sports Physiol Perform. 2010 Sep;5(3):276-91. doi: 10.1123/ijspp.5.3.276.

    PMID: 20861519BACKGROUND

  • Ranieri LE, Casado A, Martin D, Trujillo-Colmena D, Gil-Arias A, Kenneally M, Jimenez A. Performance and Physiological Effects of Race Pace-Based Versus Heart Rate Variability-Guided Training Prescription in Runners. Med Sci Sports Exerc. 2025 Jul 1;57(7):1510-1522. doi: 10.1249/MSS.0000000000003671. Epub 2025 Feb 12.

    PMID: 39935030BACKGROUND

Study Officials

  • Arturo Casado, PhD

    Universidad Rey Juan Carlos

    STUDY DIRECTOR

Study Design

Study Type
interventional
Phase
not applicable
Allocation
RANDOMIZED
Masking
SINGLE
Who Masked
INVESTIGATOR
Purpose
OTHER
Intervention Model
PARALLEL
Model Details: This study follows a parallel-group interventional design in which participants are allocated to one of three training intensity distribution (TID) models: polarized, threshold, or pyramidal. Each group performs an 8-week structured endurance training program based on the assigned intensity distribution, while maintaining comparable training frequency and overall volume across groups. Training intensity is prescribed individually using a five-zone model derived from baseline physiological assessments, including ventilatory thresholds and maximal oxygen uptake (VO₂max). The primary distinction between groups lies in the relative proportion of time spent in each intensity zone, reflecting the specific characteristics of the three TID approaches. All participants undergo identical pre- and post-intervention testing procedures to assess physiological and performance adaptations. Training sessions are monitored using GPS-enabled sport watches to ensure adherence to the prescribed intensit
Sponsor Type
OTHER
Responsible Party
PRINCIPAL INVESTIGATOR
PI Title
PhD student

Study Record Dates

First Submitted

April 27, 2026

First Posted

May 4, 2026

Study Start

April 1, 2024

Primary Completion

July 30, 2024

Study Completion

April 20, 2026

Last Updated

May 4, 2026

Record last verified: 2026-04

Data Sharing

IPD Sharing
Will not share

Locations

ES(1)