The Effects of High-Intensity Functional Training in Tactical Populations (HIFT)

February 8, 2026 updated by: Shawn M. Arent, University of South Carolina

The Effects of High-Intensity Functional Training Versus Traditional Strength Training or Concurrent Training on Performance and Readiness in Tactical Populations

The purpose of this study is to investigate the effects of high-intensity functional training (HIFT) as compared to traditional resistance training (RT) and concurrent training consisting of RT and high-intensity interval training (HIIT) on physical performance metrics, body composition, and mental and physical readiness of tactical personnel.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

This study assesses the impact of 8-weeks of high-intensity functional training (HIFT) as compared to traditional resistance training (RT) and concurrent training consisting of RT and high-intensity interval training (HIIT) on various performance outcomes. The main questions the study aims to answer are:

  • Evaluate the distinct effects of HIFT, RT, and RT plus HIIT over eight weeks on physical performance and body composition measures in tactical men and women.
  • Determine the distress, training load, and physical readiness associated with each of the three distinct training interventions over eight weeks.

Participants will:

  • Take part in 10-weeks total of study-related activity.
  • Complete four total sessions of pre and post-testing sessions, which include body composition, maximal oxygen uptake testing (VO2max), upper and lower body maximal strength, and lower body power.
  • Be randomly assigned to an exercise training intervention.

Study Type

Interventional

Enrollment (Actual)

44

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • United States
    • South Carolina
      • Columbia, South Carolina, United States, 29208
        • University of South Carolina Sport Science Lab

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • Males and females between the ages of 18 and 35 (inclusive) and enrolled in a reserve officer training corps program.
  • Subject has provided written and dated informed consent to participate in the study.
  • Subject is in good health as determined by medical history and is cleared for exercise.
  • BMI between 17.0 and 29.9 kg/m2.
  • "Good" category or greater for their aerobic capacity according to the American College of Sports Medicine (ACSM) normative data for their age and sex as measured at their baseline visit.

Exclusion Criteria:

  • Participants with any musculoskeletal injuries that would prevent completion of these exercise programs.
  • Participants with any metabolic disorder, including known electrolyte abnormalities, uncontrolled diabetes, uncontrolled thyroid disease, adrenal disease, or hypogonadism.
  • Participants with a history of hepatorenal, musculoskeletal, autoimmune, or neurologic disease.
  • Participants who have lost or gained greater than eight pounds within three months prior to study enrollment.
  • Participants currently taking hyperlipidemic, hypoglycemic, anti-hypertensive, or anti-coagulant medications.
  • Participants who are pregnant or lactating.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Other
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: High Intensity Functional Training
Training will include power and strength movements, then 30 minutes of metabolic conditioning training comprised of whole-body multi-joint movements.
Behavioral: High-intensity functional training
Participants assigned to this group will undergo 8 weeks of high-intensity functional training.
Active Comparator: Traditional Resistance Training
This group will perform traditional resistance training.
Behavioral: Traditional resistance training
Participants assigned to this group will undergo 8 weeks of traditional strength and hypertrophy training.
Active Comparator: Concurrent Training
This group will perform traditional resistance training followed by 20 minutes of running, high intensity intervals.
Behavioral: Concurrent training
Participants assigned to this group will undergo 8 weeks of traditional strength and hypertrophy training followed by high-intensity interval aerobic training.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Changes in body composition body fat percentage.
Time Frame: Baseline and Week 10
Body fat percentage via air-displacement
Baseline and Week 10
Changes in body composition fat-free mass.
Time Frame: Baseline and Week 10
Fat-free mass via air-displacement plethysmography.
Baseline and Week 10
Changes in body composition dry fat-free mass.
Time Frame: Baseline and Week 10
Dry fat-free mass via air-displacement plethysmography and bio-electrical impedance.
Baseline and Week 10
Changes in upper body strength.
Time Frame: Baseline and week 10
Upper body strength assessed by 1 repetition maximum bench press.
Baseline and week 10
Changes in lower body strength.
Time Frame: Baseline and week 10
Lower body strength assessed by isometric mid-thigh pulls on bilateral force plates.
Baseline and week 10
Changes in maximal oxygen consumption.
Time Frame: Baseline and week 10
Changes in VO2max measured by maximal graded exercise test with indirect calorimetry.
Baseline and week 10
Changes in ventilatory threshold.
Time Frame: Baseline and week 10
Changes in ventilatory threshold measured by maximal graded exercise test with indirect calorimetry.
Baseline and week 10
Changes in velocity at VO2 max.
Time Frame: Baseline and week 10
Assessed by maximal graded exercise test with indirect calorimetry.
Baseline and week 10

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Internal training load between groups.
Time Frame: Every training session over the 8-week intervention period will be included in this calculation.
Assessed by heart rate chest strap using Edwards training impulse calculation.
Every training session over the 8-week intervention period will be included in this calculation.
Changes in training distress
Time Frame: Baseline, once per week for the 8 training weeks.
Overall training distress and subscales including depressed moods, vigor, physical signs and symptoms, sleep disturbances, perceived stress, and general fatigue using the multicomponent training distress scale, scaled 0 - 110 with higher scores indicating more distress.
Baseline, once per week for the 8 training weeks.
Changes in anaerobic power.
Time Frame: Baseline, once per week for the 8 training weeks.
Measured by countermovement jump through bilateral force plates.
Baseline, once per week for the 8 training weeks.

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

University of South Carolina

Collaborators

National Strength and Conditioning Association

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

August 26, 2024

Primary Completion (Actual)

January 1, 2026

Study Completion (Actual)

January 1, 2026

Study Registration Dates

First Submitted

August 27, 2024

First Submitted That Met QC Criteria

August 29, 2024

First Posted (Actual)

September 3, 2024

Study Record Updates

Last Update Posted (Actual)

February 11, 2026

Last Update Submitted That Met QC Criteria

February 8, 2026

Last Verified

February 1, 2026

More Information

Terms related to this study

Keywords

Other Study ID Numbers

  • Pro00137947

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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