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NCT Number: NCT07498608

Effects of Polarized and Threshold Intensity Distribution Models on Race Time and Body Composition in Recreational Runners Aged 20-45 Years.

This study aims to compare the effects of two intensity distribution training (TID) models-polarized and threshold-on 5-km race time and body composition in recreational runners aged 20 to 45 years. Participants will be randomly assigned to one of two groups and will complete a 12-week structured training program. The primary outcome will be 5-km race time, while secondary outcomes will include changes in body composition. Assessments will be conducted before and after the intervention period.

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Key information

Conditions

Physical Activity Behavior Motor Activity Physical Activity Intensity Physical Activity in Adults Running Running Endurance Running Performance

Age range

20 year–45 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Colegio San Bartolome La Merced

Bogotá, Bogota D.C., 110321, Colombia

About this study

This randomized controlled trial will investigate the effects of two different intensity distribution training (TID) models: polarized (POL) and threshold (THR), on race time and body composition in recreational runners.

A total of 40 participants aged between 20 and 45 years will be randomly assigned to either the POL group or the THR group. Both groups will complete a 12-week training intervention. The polarized model will emphasize a high volume of low-intensity training (Zone 1) with small amounts of high-intensity work (Zone 3), while the threshold model will include a greater proportion of training at moderate intensity (Zone 2).

The primary outcome will be 5-km race time measured in minutes/seconds. Secondary outcomes will include body composition variables such as body fat percentage and lean mass.

Assessments will be conducted at baseline and after the 12-week intervention. The study aims to determine whether polarized training produces superior improvements compared to threshold training in recreational runners.

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Age between 20 and 45 years.
  • 1 to 3 years of experience.
  • Men's race time between 25:00 and 40:00.
  • Women's race time between 28:00 and 43:00.
  • Must reside in Bogotá or surrounding municipalities at an altitude of 2,640 meters above sea level.
  • Must have a GPS device.

Exclusion criteria

  • Having a chronic noncommunicable disease.
  • Smoking or drinking alcohol.
  • Having a musculoskeletal injury.
  • Failing to sign the informed consent form.
  • 10% attendance rate at training sessions.

Treatment and study plan

Polarized intensity distribution model

Other

Regarding the intervention, it will last 12 weeks, a period during which physiological adaptations to endurance training occur, as Neuman (1994) states with chronological cycles of 8 to 12 weeks. For the TID POL model, the intensity distribution was as follows: Zone 1 (80%), Zone 2 (5%), and Zone 3 (15%). The training periodization for the two TID models was designed using a 3:1 weekly block structure, meaning three weeks of training followed by one week of recovery. The weekly training frequency will consist of four running sessions, each including 10 minutes of running technique drills and two strength training sessions. The running sessions will have the same training volume across the three blocks, which span weeks 1-3, 5-7, and 9-11. The first week of each block will have a volume of 240 minutes, the second week 300 minutes, and the third week 360 minutes. Recovery weeks 4, 8, and 12 will have a volume of 180 minutes.

Threshold intensity distribution model

Other

Regarding the intervention, it will last 12 weeks, a period during which physiological adaptations to endurance training occur, as Neuman (1994) states with chronological cycles of 8 to 12 weeks. For the TID THR model, the intensity distribution was as follows: Zone 1 (50%), Zone 2 (40%), and Zone 3 (10%), The training periodization for the two TID models was designed using a 3:1 weekly block structure, meaning three weeks of training followed by one week of recovery. The weekly training frequency will consist of four running sessions, each including 10 minutes of running technique drills and two strength training sessions. The running sessions will have the same training volume across the three blocks, which span weeks 1-3, 5-7, and 9-11. The first week of each block will have a volume of 240 minutes, the second week 300 minutes, and the third week 360 minutes. Recovery weeks 4, 8, and 12 will have a volume of 180 minutes.

Primary outcomes

  1. Primary Objective

    Time frame: 12 weeks

    Outcome Measure: 5-km race time Description: Time to complete a 5-km run measured in minutes and seconds.

Secondary outcomes

  1. Secondary Objective

    Time frame: 12 weeks

    Outcome Measure: Body composition Description: Body fat percentage and lean mass (Kgs) assessed using standardized methods

Sponsors and collaborators

Lead sponsor

Universidad Pedagogica Nacional, Colombia

Other

Registry information

Official study title

Effects of Polarized and Threshold Intensity Distribution Models on Race Time and Body Composition in Recreational Runners Aged 20-45 Years: a Randomized Controlled Trial

Important dates

Study start
2026
Primary completion
2026
Study completion
2026
First posted
Mar 27, 2026
Registry last updated
May 1, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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