Heat Therapy and High-Intensity Training for Exercise Intolerance

Overseen By Chad Hancock, Ph.D.

Age: 18+

Sex: Any

Trial Phase: Academic

Sponsor: Brigham Young University

Disqualifiers: Pregnancy, Cardiovascular disease, Diabetes, others

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

Compensation: Varies

Number of Visits: 3

Duration: 6 weeks

What You Need to Know Before You Apply

What is the purpose of this trial?

This trial aims to understand how exercise tolerance decreases with age and how to improve it. It tests two treatments: high-intensity interval training (HIIT) of the knee extensors and muscle heat therapy. The goal is to determine if these treatments can boost muscle function and critical power (a measure of exercise endurance) in both young and older adults. Additionally, the study examines how muscle disuse, such as leg immobilization, affects muscle function and whether heat therapy can mitigate any negative effects. Ideal participants can perform knee extension exercises and have no current heart or metabolic diseases. As an unphased trial, this study offers participants the chance to contribute to foundational research that could enhance exercise endurance across different age groups.

Will I have to stop taking my current medications?

The trial information does not specify whether you need to stop taking your current medications. It's best to discuss this with the trial coordinators or your doctor.

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

Research has shown that both High Intensity Interval Training (HIIT) and Muscle Heat Therapy are generally safe for people. Studies have found that HIIT is safe and well-tolerated by older adults, even those with knee problems. While HIIT might cause some muscle soreness and temporary increases in certain markers of muscle damage, these effects are manageable.

Muscle Heat Therapy, which uses short-wave diathermy to apply heat, effectively reduces pain and improves quality of life without major side effects. It is a common and safe treatment for managing muscle and joint issues.

Research also supports the safety of using heat therapy when a limb is immobilized, suggesting it helps reduce muscle loss during inactivity. This method can help maintain muscle strength even when a limb can't move.

Overall, these therapies are well-tolerated and have a strong safety record in humans, as supported by various studies. ^{1 2 3 4 5}

Why are researchers excited about this trial's treatments?

Researchers are excited about these treatments because they offer innovative approaches to tackling exercise intolerance. Unlike traditional exercise programs that typically involve whole-body workouts, this study focuses on high-intensity interval training specifically targeting the knee extensors. This approach could lead to more efficient improvements in muscle function. Additionally, the use of muscle heat therapy is intriguing as it employs shortwave diathermy to elevate muscle temperature, potentially enhancing muscle performance without the need for physical exertion. This technique could be particularly beneficial for individuals unable to engage in intense physical activity, offering a novel, non-invasive way to improve muscle function.

What evidence suggests that this trial's treatments could be effective for improving exercise tolerance?

This trial will compare the effects of high-intensity interval training (HIIT) and muscle heat therapy on exercise intolerance. Studies have shown that HIIT can strengthen legs and improve overall health, even for those with knee problems. It may also enhance knee mobility and reduce pain, although further research is needed for confirmation. Meanwhile, research suggests that muscle heat therapy can enhance muscle function and reduce pain by warming them up. Heat therapy might also aid in faster muscle recovery after exercise. Both treatments show promise in improving muscle function and exercise capacity. Participants in this trial will be assigned to different treatment arms to evaluate these effects. ^{6 7 8 9 10}

Who Is on the Research Team?

Jayson Gifford, Ph.D.

Principal Investigator

Brigham Young University

Robert Hyldahl, Ph.D.

Principal Investigator

Brigham Young Univeristy

Are You a Good Fit for This Trial?

This trial is for individuals aged 18-95 who can perform knee extension exercises and have no current cardiovascular or metabolic diseases like heart failure or diabetes. It's not suitable for those who are pregnant, have been exercising regularly in the last six months, or cannot do knee extensions.

Inclusion Criteria

You can perform an exercise that involves straightening your knee.

I do not have heart disease or diabetes.

Exclusion Criteria

You are currently pregnant.

I have a heart condition or diabetes.

You are unable to do a specific knee exercise.

Timeline for a Trial Participant

Screening

Participants are screened for eligibility to participate in the trial

2-4 weeks

Treatment

Participants undergo either High Intensity Interval Training or Muscle Heat Therapy for 6 weeks

6 weeks

3 visits per week (in-person)

Immobilization with Heat Therapy

Participants undergo 2 weeks of leg immobilization with daily heat therapy

2 weeks

Daily visits (in-person)

Follow-up

Participants are monitored for safety and effectiveness after treatment

4 weeks

What Are the Treatments Tested in This Trial?

Interventions

• High Intensity Interval Training of the Knee Extensors
• Muscle Disuse
• Muscle Heat Therapy
• Sham Heat Therapy

Trial Overview The study tests how well High Intensity Interval Training (HIIT) and Muscle Heat Therapy improve muscle function and exercise tolerance in young and older adults. It also looks at the effects of leg immobilization on these factors and if heat therapy can minimize its impact.

How Is the Trial Designed?

Group I: Effect of Muscle Heat Therapy Experimental Treatment 1 Intervention

Young and older subjects will participate in single-leg,heat therapy training of a single leg ( quadriceps femoris, 120 minutes of shortwave diathermy to raise the muscle temperature to \~39C) 3 times a week for 6 weeks. Muscle function and knee extensor critical power will be measured before and after the 6 weeks of treatment.

Group II: Effect of Immobilization with Daily Heat Therapy Experimental Treatment 1 Intervention

Young subjects (18-35 years) will undergo 2 weeks of leg immobilization while receiving 2 hours of heat therapy treatment each day. Heat therapy will consist of 120 minutes of shortwave diathermy to raise the quadriceps femoris muscle temperature to \~39C. Muscle function and knee extensor critical power will be measured before and after the 2 weeks of leg immobilization.

Group III: Effect of High Intensity Interval Training Experimental Treatment 1 Intervention

Young and older subjects will participate in single-leg, high-intensity interval training of the right knee extensors (4 intervals of 4 minutes at 80% of max aerobic power with 4 minute rest intervals between, 3x per week for 6 weeks). Muscle function and knee extensor critical power will be measured before and after the 6 weeks of treatment.

Group IV: Effect of Sham Muscle Heat Therapy Placebo Group 1 Intervention

Young and older subjects will participate in a sham treatment of single-leg,heat therapy training of the right knee extensors (120 minutes with shortwave diathermy unit positioned on leg, but not turned on) 3 times a week for 6 weeks. Muscle function and knee extensor critical power will be measured before and after the 6 weeks of treatment.

Group V: Effect of Immobilization with Daily Sham Heat Therapy Placebo Group 1 Intervention

Young subjects (18-35 years) will undergo 2 weeks of leg immobilization while receiving 2 hours of a sham heat therapy treatment each day. For the sham treatment, the heating device will be applied to the limb, but, unbeknownst to the participant, it will not be turned on. Muscle function and knee extensor critical power will be measured before and after the 2 weeks of leg immobilization.

Who Is Running the Clinical Trial?

Brigham Young University

Lead Sponsor

Trials

23

Recruited

10,200+

Citations

1. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC12245925/

Effect of high-intensity training on improving knee flexion ... High-intensity exercise significantly improves knee flexion strength, leg press strength, and KOOS symptoms and QoL in knee osteoarthritis patients.

2. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC8516105/

High‐Intensity Interval Training for Knee Osteoarthritis In this 12-week pilot study, HIIT improved multiple aspects of health in individuals with knee OA; larger studies are needed.

3. jamanetwork.com jamanetwork.com/journals/jama/fullarticle/2776330

Effect of High-Intensity Strength Training on Knee Pain and ... High-intensity strength training, compared with low-intensity strength training and an attention control, did not significantly improve knee pain or knee joint ...

4. cdn.clinicaltrials.gov cdn.clinicaltrials.gov/large-docs/68/NCT03281668/Prot_SAP_000.pdf

Feasibility of High Intensity Interval Training for Knee ... Hypothesis: Patients with knee OA will have clinically important improvements in physical function, knee OA symptomatic burden (pain), balance, ...

5. acrjournals.onlinelibrary.wiley.com acrjournals.onlinelibrary.wiley.com/doi/abs/10.1002/acr2.11318

High‐Intensity Interval Training for Knee Osteoarthritis: A Pilot ... In this 12-week pilot study, HIIT improved multiple aspects of health in individuals with knee OA; larger studies are needed.

6. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC10671292/

Exercise-Induced Muscle Damage after a High-Intensity ... HIIT protocols were able to promote changes in markers of exercise-induced muscle damage, evidenced by increases in CK, Mb, LDH, AST, ALT, pain, ...

7. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC7887656/

Effect of High-Intensity Strength Training on Knee Pain and ... However, a prior study suggested that short-term, high-intensity strength training was safe and well tolerated by older adults with knee ...

8. sciencedirect.com sciencedirect.com/science/article/pii/S2095254616300102

High-intensity interval training (HIIT) for patients with ... This review highlights present research literature for various forms of HIIT in comparison to traditional moderate-intensity continuous exercise training (MCT).

9. frontiersin.org frontiersin.org/journals/physiology/articles/10.3389/fphys.2025.1561697/full

Effect of high-intensity training on improving knee flexion ... High-intensity exercise significantly improves knee flexion strength, leg press strength, and KOOS symptoms and QoL in knee osteoarthritis patients.

10. ijbnpa.biomedcentral.com ijbnpa.biomedcentral.com/articles/10.1186/s12966-023-01535-w

Rates of compliance and adherence to high-intensity interval ... Meta-analyses were conducted to discern differences in compliance and adherence between HIIT vs. MICT. Sensitivity analyses, publication bias, ...