High-Intensity Functional Training for Healthy Individuals

(HIFT Trial)

Overseen By Shawn M Arent, PhD

Age: 18 - 65

Sex: Any

Trial Phase: Academic

Sponsor: University of South Carolina

Must not be taking: Hyperlipidemic, Hypoglycemic, Anti-hypertensive, Anti-coagulant

Disqualifiers: Musculoskeletal injuries, Metabolic disorders, Neurologic disease, others

No Placebo Group All trial participants will receive the active study treatment (no placebo)

Compensation: Varies

Number of Visits: 7

48 Participants Needed

What You Need to Know Before You Apply

What is the purpose of this trial?

This trial examines different workouts to determine their effects on physical performance and readiness. It compares high-intensity functional training (HIFT) with traditional resistance training and a combination of resistance and high-intensity interval training (HIIT), known as concurrent training. The goal is to identify which workout best improves fitness, body composition, and mental and physical readiness in tactical personnel. Healthy individuals aged 18 to 35 who are part of a reserve officer training program may be suitable candidates for this trial. As an unphased trial, it offers participants the chance to contribute to valuable research that could enhance training programs for tactical personnel.

Will I have to stop taking my current medications?

The trial requires that participants are not currently taking medications for high cholesterol, blood sugar, high blood pressure, or blood thinning. If you are on these medications, you would not be eligible to participate.

Is there any evidence suggesting that this trial's treatments are likely to be safe?

Research has shown that high-intensity functional training (HIFT) is generally safe for most people, though some risk of injury exists. In one study, 18% of participants reported injuries at some point during their training, while another 37.5% experienced injuries during a specific session. These findings suggest that while HIFT is mostly safe, caution and proper form are important.

Conversely, concurrent training, which combines different types of exercises, has improved fitness without major safety concerns. Studies have found benefits such as better body shape and heart health, with no significant reports of harm, making it a relatively safe choice.

Both HIFT and concurrent training aim to enhance fitness and health. As with any exercise, following guidelines and paying attention to the body can help prevent injuries. ^{1 2 3 4 5}

Why are researchers excited about this trial's treatments?

Researchers are excited about the High-Intensity Functional Training (HIFT) in this trial because it offers a dynamic approach that differs from traditional exercise routines. Unlike standard resistance training, which focuses on isolated muscle groups, HIFT combines power and strength movements with metabolic conditioning. This means participants engage in whole-body, multi-joint exercises aimed at improving overall fitness in a more comprehensive and efficient way. Additionally, the concurrent training arm, which integrates high-intensity intervals with resistance training, could enhance cardiovascular benefits alongside muscle strengthening. These innovative methods have the potential to deliver faster and broader fitness improvements, making them appealing to those looking to elevate their fitness levels beyond what typical gym workouts offer.

What evidence suggests that this trial's treatments could be effective for improving physical performance and readiness?

Research has shown that high-intensity functional training (HIFT), a treatment in this trial, can enhance endurance, strength, and fatigue management. It also improves muscle function and supports heart and metabolic health, similar to other intense workouts. Another treatment option, concurrent training, combines different exercise types and has been found to boost both muscle and heart health. This training can also increase maximum strength in individuals already engaged in strength training. Both HIFT and concurrent training provide significant physical benefits, though they operate in slightly different ways. ^{1 3 6 7 8}

Are You a Good Fit for This Trial?

This trial is for healthy tactical personnel interested in improving physical performance, body composition, and readiness. Participants should be currently active in their field without any medical conditions that limit intense exercise.

Inclusion Criteria

BMI between 17.0 and 29.9 kg/m2

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

Exclusion Criteria

I do not have uncontrolled diabetes, thyroid, adrenal diseases, or any severe electrolyte imbalances.

I have a history of liver, kidney, muscle, autoimmune, or nerve disease.

I have not lost or gained more than 8 pounds in the last 3 months.

Timeline for a Trial Participant

Screening

Participants are screened for eligibility to participate in the trial

2 weeks

Pre-testing

Participants complete pre-testing sessions including body composition, VO2max, upper and lower body maximal strength, and lower body power assessments

1 week

2 visits (in-person)

Training Intervention

Participants are randomly assigned to one of three training interventions: High-Intensity Functional Training, Traditional Resistance Training, or Concurrent Training, and undergo 8 weeks of training

8 weeks

3 sessions per week (in-person)

Post-testing

Participants complete post-testing sessions similar to pre-testing to assess changes in performance metrics

1 week

2 visits (in-person)

Follow-up

Participants are monitored for any delayed effects or additional data collection

2 weeks

What Are the Treatments Tested in This Trial?

Interventions

• Concurrent training
• High-intensity functional training
• Traditional resistance training

Trial Overview The study compares high-intensity functional training (HIFT) with traditional resistance training (RT) and a combination of RT and high-intensity interval training (HIIT). It measures the impact on fitness levels, body shape changes, and mental/physical preparedness.

How Is the Trial Designed?

Group I: High Intensity Functional Training Experimental Treatment 1 Intervention

Training will include power and strength movements, then 30 minutes of metabolic conditioning training comprised of whole-body multi-joint movements.

Group II: Traditional Resistance Training Active Control 1 Intervention

This group will perform traditional resistance training.

Group III: Concurrent Training Active Control 1 Intervention

This group will perform traditional resistance training followed by 20 minutes of running, high intensity intervals.

Who Is Running the Clinical Trial?

University of South Carolina

Lead Sponsor

Trials

233

Recruited

122,000+

National Strength and Conditioning Association

Collaborator

Trials

3

Recruited

110+

National Strength and Conditioning Association

Collaborator

Published Research Related to This Trial

High-intensity functional training (HIFT) focuses on functional, multi-joint movements that can be adapted for any fitness level, potentially leading to greater muscle recruitment compared to traditional exercises.

While high-intensity interval training (HIIT) has been well-studied for its metabolic and cardiorespiratory benefits, the effects of HIFT are less understood, highlighting the need for further research to evaluate its impact on health and fitness outcomes.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

High-Intensity Functional Training (HIFT): Definition and Research Implications for Improved Fitness. Feito, Y., Heinrich, KM., Butcher, SJ., et al.[2022]

High-intensity functional training (HIFT) resulted in significantly higher peak heart rates and oxygen consumption compared to traditional workouts, indicating greater cardiorespiratory stress during exercise.

HIFT also led to higher aerobic energy expenditure in males, suggesting it may be more effective for burning calories, although this effect was not observed in females.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Cardiorespiratory responses to acute bouts of high-intensity functional training and traditional exercise in physically active adults. Brisebois, MF., Biggerstaff, KD., Nichols, DL.[2022]

A 16-week study involving 35 older men showed that both traditional strength training (TST) combined with high-intensity interval training (HIIT) and power training (PT) combined with HIIT equally improved functional performance, cardiorespiratory fitness, and body composition.

Both training methods resulted in significant enhancements in functional tests and cardiopulmonary measures, indicating that older adults can benefit from either approach without a difference in effectiveness.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Effects of high-intensity interval training combined with traditional strength or power training on functionality and physical fitness in healthy older men: A randomized controlled trial. Müller, DC., Boeno, FP., Izquierdo, M., et al.[2021]

High-Intensity Functional Training (HIFT) combines elements of high-intensity interval training and strength exercises, leading to improved cardiovascular fitness and strength due to greater muscle recruitment compared to traditional aerobic exercises.

HIFT is associated with enhanced health markers, including cardiovascular and metabolic health, as well as cognitive function, which may contribute to reduced all-cause mortality.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

High-Intensity Functional Training: Molecular Mechanisms and Benefits. Ben-Zeev, T., Okun, E.[2022]

High Intensity Functional Training (HIFT) programs, such as CrossFit and HITT, offer practical benefits for military personnel, including shorter training times and lower injury potential compared to traditional endurance training, while still achieving significant fitness outcomes.

HIFT promotes various health benefits, including improved metabolic conditioning and muscular strength, and is scalable to all fitness levels, making it a recommended standard for military physical training despite the need for further research on its implementation and comparison with traditional training methods.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

The Benefits of High-Intensity Functional Training Fitness Programs for Military Personnel. Haddock, CK., Poston, WS., Heinrich, KM., et al.[2022]

In a survey of 3049 CrossFit participants, 30.5% reported injuries over the past year, with the most common injuries affecting the shoulders (39%) and back (36%).

The overall injury rate was found to be relatively low at 0.27 per 1000 hours of training, suggesting that CrossFit is safer than traditional training methods, although beginners and those training less frequently are at higher risk for injuries.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

A 4-Year Analysis of the Incidence of Injuries Among CrossFit-Trained Participants. Feito, Y., Burrows, EK., Tabb, LP.[2022]

High Intensity Functional Training (HIFT) athletes demonstrated aerobic capacity (VO2peak) comparable to endurance athletes, indicating that HIFT can effectively improve cardiovascular fitness.

HIFT athletes also exhibited significant strength and power outputs similar to power athletes, suggesting that HIFT is an effective training method for enhancing both endurance and strength components in physical fitness.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Physiological profile comparison between high intensity functional training, endurance and power athletes. Adami, PE., Rocchi, JE., Melke, N., et al.[2022]

Injuries during high-intensity functional training (HIFT) occur at rates comparable to other sports and exercise programs, with a mean injury prevalence of 35% and an injury rate of about 3 injuries per 1,000 hours of training based on a comprehensive review of 24 studies.

The most common injuries in HIFT are to the shoulders, backs, and knees, primarily linked to weightlifting exercises, indicating that while HIFT can be effective, attention to technique and injury prevention is crucial.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Injuries During High-Intensity Functional Training. Knapik, JJ.[2022]

A 16-week High Intensity Functional Training (HIFT) program led to significant improvements in strength and metabolic conditioning for both men and women, with notable performance gains across various workouts.

Women showed greater enhancements in Bone Mineral Content (BMC) compared to men, particularly in the trunk area, indicating potential gender differences in bone health adaptations from HIFT.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Changes in body composition, bone metabolism, strength, and skill-specific performance resulting from 16-weeks of HIFT. Feito, Y., Hoffstetter, W., Serafini, P., et al.[2023]

The study found an overall injury rate of 3.51 injuries per 1000 hours of high intensity functional training (HIFT), with 59.2% of participants experiencing two or more injuries, primarily affecting the shoulder (21.3%), lower back (18.3%), and knee (13.4%).

Interestingly, experienced athletes (training over 12 months) were more prone to injuries compared to newer participants, but factors like warm-up and cooldown practices, training frequency, and participation in other sports did not significantly influence injury rates.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Epidemiology of High Intensity Functional Training (HIFT) injuries in Brazil. Serafim, TT., Maffulli, N., Migliorini, F., et al.[2023]

A systematic review of 28 studies involving 11,089 participants found that the overall injury prevalence during high-intensity functional training (HIFT) is 36%, with an injury rate of 4.3 injuries per 1000 hours of training.

The most common injuries occurred in the shoulder and back/spine (both 26%), indicating that these areas may be particularly vulnerable during HIFT, and highlighting the need for more prospective studies to better understand injury risks.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Injuries During High-Intensity Functional Training: Systematic Review and Meta-Analysis. Knapik, JJ.[2022]

Citations

1. frontiersin.org frontiersin.org/journals/physiology/articles/10.3389/fphys.2020.00572/full

The Effects of Concurrent Training Combining Both ... (2018) reported no significant change in blood cholesterol and glucose outcomes after 12 weeks (2 sessions/week) of concurrent training (50 min ...

2. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC7300209/

The Effects of Concurrent Training Combining Both ... Both training groups improved waist circumference (RT+MICT: P = 0.019; RT+HIIT: P = 0.003), but not body weight, fat mass or fat-free mass (P ≥ ...

3. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC5950732/

The Effect of Two Different Concurrent Training Programs ... The results of the present study suggest that highly strength-trained individuals can improve their maximal strength by concurrently undergoing resistance and ...

4. sciencedirect.com sciencedirect.com/science/article/abs/pii/S0531556521000966

Effects of high-intensity interval training combined with ... Concurrent training promotes improvements on neuromuscular and cardiorespiratory functions. •. There is a lack of studies comparing traditional versus power ...

5. nature.com nature.com/articles/s41598-025-11809-x

Effects of high-intensity interval training on physical fitness ... A 10-week block of combined high-intensity endurance and strength training produced similar changes in dynamic strength, body composition ...

6. sciencedirect.com sciencedirect.com/science/article/pii/S2950273X25000268

The effect of endurance, resistance and concurrent training ... The purpose of this study was to determine the effects of three exercise-training programs on respiratory capacity and pulmonary function in patients with CF.

7. mdpi.com mdpi.com/2218-1989/15/4/278

Effects of a 6-Week Concurrent Training Program ... Concurrent training (RT + MICT and RT + HIIT) for 6 weeks showed significant improvements in body composition, blood pressure, vascular function, ANS function, ...

8. journals.lww.com journals.lww.com/md-journal/fulltext/2024/12270/optimizing_concurrent_training_programs__a_review.22.aspx

Optimizing concurrent training programs: A review on factors The purpose of this study is to explore the factors that should be considered when designing concurrent training programs to minimize the “interference effect.”