Acute Effects of High-intensity Interval Aerobic and Functional Training at Different Intensities

NCT07180550 | Recruiting

• 1 other identifier: PI-DOC008-HIIT-HIFT-FT
• Study Type: interventional
• Target: 27
• Locations: 1 country
• Sites: 1

Brief Summary

Moderate-intensity physical exercise is widely recognized for its health benefits, yet time constraints limit adherence. High-intensity interval training (HIIT) has gained popularity as a more time-efficient alternative, eliciting significant cardiovascular, respiratory, metabolic, and neuromuscular responses. More recently, functional strength exercises have been integrated into high-intensity training, leading to high-intensity functional training (HIFT) and moderate-intensity functional training (MIFT). However, the acute physiological responses to these modalities remain underexplored compared to traditional HIIT (running or cycling) and strength training. This study aims to assess and compare the acute cardiovascular, metabolic, and neuromuscular responses of HIFT, MIFT, HIIT, and traditional strength training in healthy, physically active adults to inform their potential application in special populations.

Conditions

High Intensity Interval Training (Running); High Intensity Functional Training; Moderate Intensity Functional Training; High Intensity Interval Training (Cycling); High Intensity Traditional Strength Training; Moderate Intensity Traditional Strength Training

Keywords

Metabolic demand; Oxygen consumption; Heart rate variability; Interval training; Strength training

Outcome Measures

Primary Outcomes (1)

• Heart rate variability

  The heart rate variability (HRV) of the participants will be assessed by monitoring their heart rate, which reflects the variation in the intervals between heartbeats (R-R intervals). This measure is a useful tool in monitoring patient health, as it estimates the balance between the sympathetic and parasympathetic activity of the autonomic nervous system. To evaluate heart rate variability, a Polar H10 heart rate monitor (Polar Electro Oy, Kempele, Finland) and a mobile application, specifically Elite HRV, will be used. Heart rate variability will be monitored daily during the week leading up to the initial assessment visits. Participants will be instructed to take the measurement for the first 5 minutes upon waking and while fasting. Subsequently, heart rate variability will be assessed immediately before each training condition, as well as immediately after, at 2, 24, 48, and 72 hours after finishing each training condition.

  Week 0 (baseline), Weeks 1-4 (during intervention and 24, 48, and 72 hours post-intervention)

Secondary Outcomes (6)

• Post-exercise oxygen debt

  Weeks 2-4 (after every intervention session)

• Delayed onset muscle soreness

  Weeks 2-4 (24, 48, and 72 hours post-intervention)

• Satisfaction with the type of training

  Weeks 2-4 (right after every intervention session and 24 hours post-intervention)

• Subjective post-exercise fatigue

  Weeks 2-4 (right after every intervention session and 24 hours post-intervention)

• Perceived effort

  Weeks 2-4 (right after every intervention session and 24, 48, and 72 hours post-intervention)

Other Outcomes (11)

• Physical activity levels

  Week 0 (baseline)

• Cardiorespiratory fitness

  Week 1 (baseline)

• Cardiorespiratory fitness

  Week 1 (baseline)

Study Arms (6)

High-intensity interval training (running)

EXPERIMENTAL

Participants will perform a high-intensity interval training based on six sets of 2-minute runs at an intensity of 90-95% of the maximal aerobic speed (MAS) on a treadmill. The recovery between each set will be 2 minutes, during which the subject will walk at an intensity of 50-60% of MAS.

Other: High-intensity interval training, running

High-intensity interval training (cycling)

EXPERIMENTAL

Participants will perform a high-intensity interval training based on six sets of 2-minute cycling will be performed at an intensity of 90-95% of the maximal heart rate on a stationary bike. The recovery between each set will be 2 minutes, during which the subject will cycle at an intensity of 50-60% of maximal heart rate.

Other: High-intensity interval training, cycling

High-intensity functional training

EXPERIMENTAL

Participants will perform a high-intensity functional training based on three sets of six repetitions will be performed at 80% of the one repetition maximum (1-RM) for six exercises. The recovery between exercises will be the minimum time required to switch from one exercise to the next, and between sets, it will be two minutes. Participants will be instructed to move the load as quickly as possible during each repetition.

Other: High-intensity functional training

Moderate-intensity functional training

EXPERIMENTAL

Participants will perform a moderate-intensity functional training based on three sets of six repetitions will be performed at 60% of the 1-RM for six exercises. The recovery between exercises will be the minimum time required to switch from one exercise to the next, and between sets, it will be two minutes. Participants will be instructed to move the load as quickly as possible during each repetition.

Other: Moderate-intensity functional training

High-intensity traditional training

EXPERIMENTAL

Participants will perform a high-intensity traditional training based on three sets of six repetitions will be performed at 80% of the 1-RM for six exercises. The recovery after each set will be two minutes of passive rest. Participants will be instructed to move the load as quickly as possible during each repetition.

Other: High intensity traditional strength training

Moderate-intensity traditional training

EXPERIMENTAL

Participants will perform a high-intensity traditional training based on three sets of six repetitions will be performed at 60% of the 1-RM for six exercises. The recovery after each set will be two minutes of passive rest. Participants will be instructed to move the load as quickly as possible during each repetition.

Other: Moderate intensity traditional strength training

Interventions

High-intensity interval training, running OTHER

Six sets of 2-minute runs will be performed at an intensity of 90-95% of the maximal aerobic speed (MAS) on a treadmill. The recovery between each set will be 2 minutes, during which the subject will walk at an intensity of 50-60% of MAS.

High-intensity interval training (running)

High-intensity interval training, cycling OTHER

Six sets of 2-minute cycling will be performed at an intensity of 90-95% of the maximal heart rate on a stationary bike. The recovery between each set will be 2 minutes, during which the subject will cycle at an intensity of 50-60% of maximal heart rate.

High-intensity interval training (cycling)

High-intensity functional training OTHER

Three sets of six repetitions will be performed at 80% of the one repetition-maximum (1-RM) for six exercises. The recovery between exercises will be the minimum time required to switch from one exercise to the next, and between sets, it will be two minutes. Participants will be instructed to move the load as quickly as possible during each repetition.

High-intensity functional training

Moderate-intensity functional training OTHER

Three sets of six repetitions will be performed at 60% of the 1-RM for six exercises. The recovery between exercises will be the minimum time required to switch from one exercise to the next, and between sets, it will be two minutes. Participants will be instructed to move the load as quickly as possible during each repetition.

Moderate-intensity functional training

Moderate intensity traditional strength training OTHER

Three sets of six repetitions will be performed at 60% of the 1-RM for six exercises. The recovery after each set will be two minutes of passive rest. Participants will be instructed to move the load as quickly as possible during each repetition.

Moderate-intensity traditional training

High intensity traditional strength training OTHER

Three sets of six repetitions will be performed at 80% of the 1-RM for six exercises. The recovery after each set will be two minutes of passive rest. Participants will be instructed to move the load as quickly as possible during each repetition.

High-intensity traditional training

Eligibility Criteria

• Age: 18 Years - 100 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Be 18 years of age or older.
• Have at least 6 months of experience in strength training with intensities greater than 75% of one maximum repetition (1-RM).
• Be classified as active according to the International Physical Activity Questionnaire (IPAQ) score.

You may not qualify if:

• Musculoskeletal injury within the 6 months prior to the first visit to the laboratory.
• Recent major surgery (\<3 months).
• Having a medical condition in which physical activity is contraindicated (assessed with the Physical Activity Readiness Questionnaire, PAR-Q+).

Sponsors & Collaborators

• European University Miguel de Cervantes: lead
• Hospital Clínico Universitario de Valladolid: collaborator

Study Sites (1)

Miguel de Cervantes European University

Valladolid, Valladolid, 47012, Spain

RECRUITING

MeSH Terms

Interventions

High-Intensity Interval Training; Running

Intervention Hierarchy (Ancestors)

Physical Conditioning, Human; Exercise; Motor Activity; Movement; Musculoskeletal Physiological Phenomena; Musculoskeletal and Neural Physiological Phenomena; Locomotion

Central Study Contacts

Susana López Ortiz, PhD

CONTACT

983001000; cbaladron@icicor.es

Susana López Ortiz, PhD

CONTACT

cbaladron@icicor.es

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: SINGLE
• Who Masked: INVESTIGATOR
• Masking Details: The researcher responsible for analyzing the data will be blinded to the study conditions.
• Purpose: OTHER
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Model Details: Quasi-experimental, crossover interventional study

Study Record Dates

• First Submitted: September 9, 2025
• First Posted: September 18, 2025
• Study Start: October 12, 2025
• Primary Completion (Estimated): January 1, 2027
• Study Completion (Estimated): January 31, 2027
• Last Updated: March 10, 2026

Record last verified: 2026-03

Data Sharing

• IPD Sharing: Will not share

Locations

ES (1)