Exercise Intensity for Fitness

(CEX Trial)

Overseen By Garett S Jackson, MSc.

Age: 18 - 65

Sex: Any

Trial Phase: Academic

Sponsor: University of British Columbia

Must not be taking: Immunomodulatory, Anti-inflammatory

Disqualifiers: Diabetes, Hypertension, Extreme diet, others

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

Compensation: Varies

Number of Visits: 21

Duration: 6 weeks

50 Participants Needed

What You Need to Know Before You Apply

What is the purpose of this trial?

This trial explores how different levels of indoor cycling intensity affect health and fitness. Participants will be divided into three groups: one cycling at a moderate pace (Moderate Intensity Continuous Training), another cycling at a harder pace (Heavy Intensity Continuous Training), and a control group that continues their normal activities. The study seeks healthy young adults who exercise regularly and do not have conditions like cardiovascular disease or diabetes. By comparing results from before and after the 6-week cycling program, researchers aim to determine which exercise intensity best enhances health and fitness. As an unphased trial, this study allows participants to contribute to valuable research on exercise and health.

Do I have to stop taking my current medications for the trial?

The trial protocol does not specify if you need to stop taking your current medications. However, if you require immunomodulatory medication for an autoimmune disease or rely heavily on over-the-counter anti-inflammatory medications, you may be excluded from participating.

What prior data suggests that these exercise protocols are safe?

Research has shown that the high-intensity training used in this study is generally safe and well-tolerated. Studies indicate that high-intensity interval training (HIIT) carries a low risk of major heart problems, even for individuals with heart issues, suggesting it is likely safe for healthy individuals as well. One study found that HIIT improves fitness and is safe for people with certain liver conditions.

Experts recommend that adults engage in at least 150 minutes of moderate-intensity training each week, which is considered low-risk for heart problems. Research supports that both high and moderate-intensity exercises have similarly low risks for heart issues.

Overall, evidence suggests that both types of training in this study are safe for healthy adults. Participants can expect these exercises to be well-tolerated, with minimal risk of side effects. ^{1 2 3 4 5}

Why are researchers excited about this trial?

Researchers are excited about this trial because it explores how different exercise intensities can impact fitness levels. Unlike typical exercise routines that may not specify intensity, this trial examines heavy and moderate intensity continuous training, specifically targeting the lactate threshold. By fine-tuning exercise intensity, the study aims to optimize cardiovascular health and performance improvements, which could lead to more effective and personalized fitness programs.

What evidence suggests that this trial's exercise intensities could be effective for improving fitness?

This trial will compare different exercise intensities to assess their impact on fitness. Participants in the Heavy Intensity Continuous Training arm will engage in high-intensity workouts. Research has shown that such workouts can increase exercise ability, aid in fat loss, and improve aerobic fitness in younger adults. Meanwhile, participants in the Moderate Intensity Continuous Training arm will perform moderate exercise, known to benefit heart health and improve body shape, especially with regular practice. Both exercise types enhance heart health and fitness, contributing to overall well-being. ^{1 6 7 8 9}

Are You a Good Fit for This Trial?

Healthy young adults aged 18-40 with a normal body mass index can participate. They should not have any immune diseases and must be willing to undergo indoor cycling sessions and blood tests.

Inclusion Criteria

Have a body mass index (BMI) between 18.5 and 30 kg/m^2

Perform between 60 and 200 minutes of aerobic physical activity per week

I do not have a history of heart disease or diabetes.

Exclusion Criteria

Are an elite endurance athlete, or training specifically for an endurance event (>3 structured aerobic training sessions, or >150 min of specific aerobic-based/endurance training per week)

Adhere to an extreme diet (e.g., ketogenic diet, time restricted feeding)

Smoke cigarettes

Timeline for a Trial Participant

Screening

Participants are screened for eligibility to participate in the trial

2-4 weeks

1 visit (in-person)

Pre-Intervention Testing

Participants undergo baseline testing including maximal cycling test and blood sample collection

1 week

1 visit (in-person)

Treatment

Participants engage in 6 weeks of moderate or heavy intensity cycling training, or no additional exercise for the control group

6 weeks

18 visits (in-person)

Post-Intervention Testing

Participants repeat the maximal cycling test and blood sample collection to assess changes

1 week

1 visit (in-person)

Follow-up

Participants are monitored for safety and effectiveness after treatment

4 weeks

What Are the Treatments Tested in This Trial?

Interventions

• Control Group
• Heavy Intensity Continuous Training
• Moderate Intensity Continuous Training

Trial Overview The study is testing the effects of different intensities of indoor cycling on fitness, health markers in the blood, inflammation, and metabolism over a period of 6 weeks. Participants will cycle at moderate or heavy intensity or continue their usual activities as a control group.

How Is the Trial Designed?

Group I: Moderate Intensity Continuous Training Experimental Treatment 1 Intervention

In this allocation, participants cycle at 70% the resistance associated with their lactate threshold

Group II: Heavy Intensity Continuous Training Experimental Treatment 1 Intervention

In this allocation, participants cycle at the resistance associated with their lactate threshold, with an additional 10% of the difference between their LT and maximal achieved watts during the test.

Group III: Control Group Experimental Treatment 1 Intervention

This group undergoes the same testing protocols as the intervention groups, but is prescribed no additional exercise.

Who Is Running the Clinical Trial?

University of British Columbia

Lead Sponsor

Trials

1,506

Recruited

2,528,000+

Published Research Related to This Trial

Both high-intensity interval training (HIIT) and moderate-intensity training (CONT) improved aerobic fitness equally over a 6-week period in a study involving 20 adults.

However, the two training methods led to different changes in cardiorespiratory coordination, suggesting that the intensity of training can influence how the body adapts to endurance exercise.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Cardiorespiratory coordination reveals training-specific physiological adaptations. Garcia-Retortillo, S., Gacto, M., O'Leary, TJ., et al.[2021]

High-intensity interval training (HIIT) is as effective, if not more so, than traditional moderate-intensity continuous training (MICT) for patients with cardiovascular disease, based on a systematic review of 23 studies involving 1117 participants.

The safety profile of HIIT in cardiac rehabilitation is promising, with only one major cardiovascular adverse event reported per 17,083 training sessions, indicating that HIIT can be safely implemented in this population.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

High-Intensity Interval Training for Patients With Cardiovascular Disease-Is It Safe? A Systematic Review. Wewege, MA., Ahn, D., Yu, J., et al.[2021]

In a study of 81 heart disease patients with very high cardiovascular risk, both moderate and high-intensity interval training (MIIT and HIIT) were found to be safe, with no adverse outcomes reported during the training.

While there were no statistically significant differences in overall exercise improvements between the training types, the HIIT group showed a trend towards greater improvements in exercise tolerance, suggesting it may be more effective than continuous moderate intensity training (MICT).

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Safety and improvement in exercise tolerance with interval training vs moderate-intensity continuous training in heart disease patient of very high cardiovascular risk. Pineda-García, AD., Lara-Vargas, JA., Ku-González, A., et al.[2022]

In an 8-week study involving 24 overweight/obese middle-aged men, both high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) resulted in similar improvements in cardiovascular fitness and fat loss, indicating that HIIT can be an effective alternative to traditional exercise methods.

Participants in both training groups reported high enjoyment levels and adherence rates over 90%, suggesting that HIIT is not only time-efficient but also well-received by individuals looking to improve their metabolic health.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

The effect of low-volume high-intensity interval training on cardiometabolic health and psychological responses in overweight/obese middle-aged men. Poon, ET., Little, JP., Sit, CH., et al.[2022]

Exercise programs for conditioning and rehabilitation must be specifically designed for either strength development or aerobic fitness, as they require different approaches in terms of intensity, duration, and frequency.

Strength training focuses on low repetitions with high resistance, while aerobic exercise involves longer durations with many repetitions, leading to distinct physiological adaptations in the body.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Strength training and aerobic exercise: comparison and contrast. Knuttgen, HG.[2016]

Both continuous moderate intensity exercise training (CMIET) and CMIET combined with a single weekly high intensity interval training (HIIT) session led to clinically meaningful improvements in cardiorespiratory fitness, with the CMIET + HIIT group showing a 10.1% increase in VO2max over 12 weeks.

Participants in the CMIET + HIIT group demonstrated 100% adherence to the training regimen, indicating that this combination of exercise is well-tolerated by previously inactive individuals at moderate risk of cardiovascular disease.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Is moderate intensity exercise training combined with high intensity interval training more effective at improving cardiorespiratory fitness than moderate intensity exercise training alone? Roxburgh, BH., Nolan, PB., Weatherwax, RM., et al.[2022]

In a study of 31 participants undergoing high-intensity functional training (HIFT) for six weeks, no significant improvements in physical performance measures such as jump height, sprinting speed, or handgrip strength were observed in either high or moderate training volume groups.

The analysis indicated that variations in training volume and frequency did not affect performance outcomes, suggesting that simply increasing training intensity may not lead to enhanced physical capabilities in HIFT practitioners.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Effects of Six Weeks of High-Intensity Functional Training on Physical Performance in Participants with Different Training Volumes and Frequencies. Teixeira, RV., Batista, GR., Mortatti, AL., et al.[2020]

Both high-intensity interval training (I HIGH) and lower intensity training (105% CP) effectively reduced the time it takes for the body to reach steady-state oxygen consumption during moderate and heavy exercise, indicating improvements in aerobic performance.

The training intensity did not significantly affect the physiological responses, such as blood lactate levels and muscle activation, suggesting that both training methods can be equally beneficial for enhancing exercise efficiency.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Short-term interval training at both lower and higher intensities in the severe exercise domain result in improvements in V̇O₂ on-kinetics. Turnes, T., de Aguiar, RA., de Oliveira Cruz, RS., et al.[2018]

In a study involving 73 coronary patients over 8 weeks, high intensity interval training (HIIT) led to a greater improvement in peak oxygen consumption (VO2peak) compared to moderate continuous training (MCT), with increases of 4.5 ml/kg/min for HIIT versus 2.46 ml/kg/min for MCT.

HIIT also significantly enhanced heart rate recovery (HRR) at both the first and second minute post-exercise, indicating better cardiovascular recovery compared to MCT, which suggests that HIIT may be more beneficial for coronary patients.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Effects of high-intensity interval versus continuous exercise training on post-exercise heart rate recovery in coronary heart-disease patients. Villelabeitia-Jaureguizar, K., Vicente-Campos, D., Senen, AB., et al.[2018]

High-intensity interval training (HIIT) is significantly more effective than moderate intensity training (MIT) for improving aerobic capacity (peak VO2) and left-ventricular ejection fraction (LVEF) in heart failure patients, based on a meta-analysis of 17 studies.

There is no significant difference in outcomes between MIT and combined aerobic and resistance training (CT), indicating that adding resistance training does not hinder aerobic improvements in heart failure patients.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Exercise Mode in Heart Failure: A Systematic Review and Meta-Analysis. Edwards, J., Shanmugam, N., Ray, R., et al.[2023]

A scoping review of 69 studies on high-intensity interval training (HIIT) in older adults found that HIIT protocols are generally well-tolerated and can provide significant health benefits, particularly in improving cardiorespiratory fitness.

Most research has focused on healthy older adults, highlighting a need for larger studies and more investigation into HIIT's effects on older adults with various health conditions.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

High-Intensity Interval Training in Older Adults: a Scoping Review. Marriott, CFS., Petrella, AFM., Marriott, ECS., et al.[2021]

High-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) both improved aerobic capacity (VO2peak) and waist circumference in breast cancer survivors over a 12-week program, but there were no significant differences between the two training methods.

While HIIT led to increases in minute ventilation and peak workload, it did not result in a greater improvement in VO2peak compared to MICT, suggesting that both training intensities are beneficial for previously trained breast cancer survivors.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Additional cardiovascular fitness when progressing from moderate- to high-intensity exercise training in previously trained breast cancer survivors. Bell, RA., Baldi, JC., Jones, LM.[2021]

A 3-week rehabilitation program using high-intensity interval training (HIIT) was safe for female breast cancer survivors, with no reported adverse events, and effectively reduced body fat without affecting overall body mass.

Both HIIT and low-to-moderate intensity exercise (LMIE) improved quality of life and reduced cancer-related fatigue, but HIIT was more time-efficient, making it a practical option for enhancing health in this population.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

A 3-week multimodal intervention involving high-intensity interval training in female cancer survivors: a randomized controlled trial. Schmitt, J., Lindner, N., Reuss-Borst, M., et al.[2021]

Maximal-intensity aerobic interval training (MAIT) significantly improved maximal oxygen uptake (O2max) by 31% in patients with acute coronary syndrome, compared to a 17% increase with high-intensity aerobic interval training (HAIT), indicating that MAIT may be more effective for enhancing cardiovascular fitness.

Both MAIT and HAIT were found to be safe, with no major cardiovascular or musculoskeletal complications reported during the 6-week training period, suggesting their suitability for cardiac rehabilitation.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

The Effect and Safety of Aerobic Interval Training According to Exercise Intensity in Acute Coronary Syndrome. Kim, C., Choi, HE.[2021]

Citations

1. sciencedirect.com sciencedirect.com/science/article/pii/S1728869X23000424

Chronic high-intensity interval training and moderate ... Our results revealed that both HIIT and MICT were effective in improving MFO during exercise in overweight and obese adults. No significant differences between ...

2. mdpi.com mdpi.com/2077-0383/14/4/1282

The Effectiveness of High-Intensity Interval Training vs. ... Results: HIIT was found to be most effective for younger individuals (18–30 years), promoting fat oxidation and muscle retention. In middle-aged adults (31–40 ...

3. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC8294064/

Evidence-Based Effects of High-Intensity Interval Training on ... Research has indicated that high-intensity interval training induces numerous physiological adaptations that improve exercise capacity.

4. nature.com nature.com/articles/s41598-024-67331-z

Comparative effects of high-intensity interval training and ... The purpose of this study was to compare the effects of High-Intensity Interval Training (HIIT) and Moderate-Intensity Continuous Training (MICT) on weight, ...

5. bmcpublichealth.biomedcentral.com bmcpublichealth.biomedcentral.com/articles/10.1186/s12889-025-22829-7

A systematic review and meta-analysis of the effectiveness of ... Results showed that HIIT significantly reduced BMI, body fat percentage, waist-to-hip ratio, and heart rate, while significantly improving VO 2 max and muscle ...

6. ahajournals.org ahajournals.org/doi/10.1161/JAHA.118.009305

High‐Intensity Interval Training for Patients With ... HIIT has shown a relatively low rate of major adverse cardiovascular events for patients with coronary artery disease or heart failure when applied within CR ...

7. heart.org heart.org/en/healthy-living/fitness/fitness-basics/aha-recs-for-physical-activity-in-adults

AHA Physical Activity Recommendations ... These recommendations are based on the Physical Activity Guidelines for Americans, 2nd edition, published by the US Department of Health and Human Services.

8. onlinelibrary.wiley.com onlinelibrary.wiley.com/doi/10.1111/sms.14652

High‐intensity interval training and cardiorespiratory fitness ... The data showed that HIIT, including the particularly intense variant “sprint interval training” (SIT), significantly increases CRF in adults ...

9. link.springer.com link.springer.com/article/10.1007/s10620-022-07779-z

High-Intensity Interval Training is Safe, Feasible and ... HIIT is safe, feasible and efficacious for improving exercise capacity and peripheral insulin sensitivity in people with NASH.