# Similar cardiometabolic effects of high- and moderate-intensity training among apparently healthy inactive adults: a randomized clinical trial

PMID: 28558739
Journal: Journal of translational medicine
Published: 2017 May 30
Authors: Ramírez-Vélez R, Tordecilla-Sanders A, Téllez-T LA, Camelo-Prieto D, Hernández-Quiñonez PA, Correa-Bautista JE, Garcia-Hermoso A, Ramirez-Campillo R, Izquierdo M

## Question

Does high-intensity interval training differ from steady-state moderate-intensity continuous training for improving metabolic syndrome risk factors and related cardiometabolic outcomes in apparently healthy physically inactive adults?

## Summary

This small randomized trial compared 12 weeks of supervised treadmill high-intensity interval training with energy-matched moderate continuous training in physically inactive Colombian adults. Both groups improved or changed several cardiometabolic markers, but HIT produced a larger reduction in the continuous metabolic syndrome Z-score, while single risk-factor changes were not consistently superior to moderate training. No adverse events were reported.

## Population

- Apparently healthy physically inactive Colombian adults, age 18-45 years, BMI 18-30 kg/m2.
- Sample size: 20
- Age: Mean 31.8 (SD 7.8) years
- Sex: 8 male (40%), 12 female (60%)
- Fitness level: Physically inactive
- Health status: Apparently healthy; excluded for AHA absolute contraindications to exercise testing

## Methodology

- Randomized clinical trial comparing HIT with MCT over 12 weeks with baseline and post-intervention cardiometabolic assessments.
- 12 weeks
- University-based supervised exercise study in Bogota, Colombia
- Randomized and controlled study design.

## Protocol

- HIT.
- Modality: Treadmill fast walking or running with incline.
- Work intervals: 4 min at 85-95% peak HRR.
- Recovery: 4 min active rest at 65% peak HRR.
- Sets or repetitions: 4 intervals.
- Intensity: 85-95% peak HRR during work intervals.
- Session duration: Variable by kcal/kg/week target; 16 min hard work plus active rests at full interval prescription.
- Frequency: 3 sessions/week.
- Program length: 12 weeks.
- Progression: Progressed from 6 kcal/kg/week during a preparatory phase to 12 kcal/kg/week by weeks 5-12.
- MCT.
- Modality: Treadmill fast walking or running with incline.
- Work intervals: Continuous exercise.
- Intensity: 60-80% heart-rate reserve.
- Session duration: Variable by kcal/kg/week target; MCT total exercise time over study 1100 +/- 258 min.
- Frequency: 3 sessions/week.
- Program length: 12 weeks.
- Progression: Same weekly energy-expenditure progression as HIT.

## Outcomes

### MetS Z-score
Status: improved
MetS Z-score improved significantly in both groups, with a significant time by group difference favoring HIT.

MCT change 1.546 (1.575), P=0.009, ES=0.82; HIT change -1.249 (1.629), P=0.015, ES=0.55; between-group difference -2.795 (95% CI 1.276 to 4.311), time x group P=0.001.

### Average number of cardiometabolic risk factors
Status: mixed
Average risk factors decreased in MCT but not HIT, with no significant between-group difference.

MCT -0.133, P=0.040, ES=0.67; HIT 0.018, P=0.294, ES=0.14; between-group P=0.227.

### Individual metabolic syndrome components
Status: mixed
No consistent between-group superiority appeared for individual MetS risk factors. Mean blood pressure decreased in HIT, while waist circumference and triglycerides decreased in MCT.

Mean BP HIT P=0.019; WC MCT P=0.006; triglycerides MCT P=0.012; no significant time x group effects for these individual risk factors.

### Fasting glucose
Status: worse/safety concern
Fasting glucose increased significantly in both groups but remained in the healthy range.

MCT P=0.039, ES=0.19; HIT P=0.001, ES=0.29; between-group P=0.078.

### Safety
Status: no clear change
No adverse events were reported.

## Practical Insights

- A supervised 4 x 4 min treadmill HIIT protocol can be completed by screened inactive adults with high session attendance.
- HIIT programming for inactive adults should include progression and monitoring rather than immediate full-dose unsupervised intensity.
- This study supports cautious claims about composite cardiometabolic risk, not broad superiority over moderate training for every risk factor.

## Limitations

- No true non-exercise control group
- Small sample size
- Single-site design
- Baseline MetS Z-score differed between groups
- Bioelectrical impedance analysis was used for body composition and is not the gold standard
- Supervised treadmill setting limits translation to unsupervised app-based workouts

## Safety And Adherence

- No adverse events were reported over the course of the investigation.
- Participants with AHA absolute contraindications to exercise testing were excluded.
- Exercise sessions were supervised and heart rate monitored.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/28558739/) (pubmed)
- [DOI](https://doi.org/10.1186/s12967-017-1216-6) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5450080/) (full text)

## Agent Guidance

Preserve the paper-level scope of this note. Do not generalize beyond the population, protocol, measured outcomes, and limitations above.