# "HIIT the Inflammation": Comparative Effects of Low-Volume Interval Training and Resistance Exercises on Inflammatory Indices in Obese Metabolic Syndrome Patients Undergoing Caloric Restriction

PMID: 35631137
Journal: Nutrients
Published: 2022 May 10
Authors: Reljic D, Dieterich W, Herrmann HJ, Neurath MF, Zopf Y

## Question

Do low-volume HIIT, single-set resistance training, whole-body electromyostimulation, and three-set resistance training differ in effects on inflammation and cardiometabolic indices during caloric restriction in obese metabolic syndrome patients?

## Summary

In obese adults with metabolic syndrome receiving calorie-restriction counseling, a very low-volume cycling HIIT program improved CRP, IL-6, hsCRP, LBP, VO2max, and metabolic syndrome severity more consistently than low-volume resistance-based alternatives. All groups lost weight, so the exercise-specific effects are most informative for inflammation and fitness.

## Population

- Adults with obesity and metabolic syndrome selected from two larger trials
- Sample size: 104
- Age: 53.7 +/- 11.4 years in abstract sample
- Sex: Men and women; no significant sex effect detected
- Fitness level: Predominantly sedentary
- Health status: BMI >=30 kg/m2 with metabolic syndrome; excluded heart disease, cancer, severe orthopedic conditions, acute inflammatory illness, unsafe exercise conditions, and pregnancy

## Methodology

- Sub-analysis of randomized controlled clinical trials with five intervention/control groups
- 12 weeks
- Controlled laboratory/training center with supervised exercise and diet counseling
- Randomized and controlled study design.

## Protocol

- Very low-volume HIIT.
- Modality: Electronically braked cycle ergometer.
- Work intervals: 1 min.
- Recovery: 1 min low-intensity recovery.
- Sets or repetitions: 5 intervals/session.
- Intensity: 80-95% HRpeak, progressed by 4-week blocks.
- Session duration: 14 min total.
- Frequency: 2 sessions/week.
- Program length: 12 weeks.
- Progression: Target HR increased from 80-85% HRpeak in weeks 1-4 to 85-90% in weeks 5-8 and 90-95% in weeks 9-12.
- Resistance exercise, WB-EMS, and inactive control.
- Modality: Single-set RT, three-set RT, whole-body electromyostimulation, or diet-only inactive control.
- Work intervals: RT performed repetitions to fatigue; WB-EMS used 6 s impulse/4 s rest.
- Recovery: RT used 2 min rest between exercises/sets; WB-EMS used 4 s rest.
- Sets or repetitions: 1-RT one set each of five machine exercises; 3-RT three sets; WB-EMS eight muscle groups with light movements.
- Intensity: RT 50-80% Fmax progression; WB-EMS perceptible contraction; control no exercise.
- Session duration: 1-RT about 15 min; 3-RT about 50 min; WB-EMS 20 min.
- Frequency: 2 sessions/week for exercise groups.
- Program length: 12 weeks.
- Progression: RT load increased every 4 weeks; WB-EMS current adjusted as needed; all groups received nutrition counseling.

## Outcomes

### Inflammation
Status: improved
LOW-HIIT reduced CRP, hsCRP, IL-6, and LBP.

CRP -1.6 mg/L p < 0.001; hsCRP -1.4 mg/L p < 0.001; IL-6 -1.1 pg/mL p = 0.020; LBP -2.1 ng/mL p = 0.004

### Group differences
Status: improved
LOW-HIIT showed larger inflammatory-marker improvements than control and low-volume resistance alternatives.

CRP, hsCRP, and LBP reductions greater than CON; LBP post-intervention lower than 1-RT, 3-RT, and WB-EMS

### MetS severity
Status: improved
Metabolic syndrome severity improved in LOW-HIIT, 1-RT, and 3-RT.

LOW-HIIT -1.84 p < 0.001; 1-RT -1.58 p = 0.005; 3-RT -2.36 p < 0.001

### VO2max
Status: improved
VO2max increased only in LOW-HIIT.

+3.0 mL/kg/min, 95% CI 2.0 to 4.0, p < 0.001

### Weight loss
Status: improved
All groups lost weight similarly during caloric restriction.

Average relative weight loss 3.6%; no significant between-group difference

## Practical Insights

- A 14-minute, twice-weekly cycling HIIT protocol can improve inflammation markers in a high-risk metabolic population under supervision.
- Cardiovascular low-volume exercise appeared more potent for inflammatory markers than low-volume resistance modalities.
- Diet counseling was provided to all groups, so this is evidence for exercise added to caloric restriction, not exercise alone.

## Limitations

- Sub-analysis combining prior trials
- Self-reported diet records
- No high-volume MICT comparator
- No specific anti-inflammatory blood markers beyond selected panel
- Controlled supervised setting limits real-world generalization

## Safety And Adherence

- Exercise eligibility was screened by health examination, resting ECG, and CPET; adverse events were not emphasized in the extracted article text.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/35631137/) (pubmed)
- [DOI](https://doi.org/10.3390/nu14101996) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9145085/) (full text)

## Agent Guidance

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