# High-Intensity Interval Training Decreases Muscle Sympathetic Nerve Activity in Men With Essential Hypertension and in Normotensive Controls

PMID: 33013285
Journal: Frontiers in Neuroscience
Published: 2020
Authors: Ehlers TS, Sverrisdottir Y, Bangsbo J, Gunnarsson TP

## Question

Does 6 weeks of 10-20-30 cycling HIIT reduce muscle sympathetic nerve activity, blood pressure, fat mass, and fitness markers in men with essential hypertension and normotensive controls?

## Summary

In 24 sedentary older men, 6 weeks of supervised 10-20-30 cycling HIIT reduced resting muscle sympathetic nerve activity in both hypertensive and normotensive groups. Nighttime diastolic and mean arterial blood pressure fell in hypertensive men, body fat improved in both groups, and the authors discussed HIIT as time-efficient, though the study was small and male-only.

## Population

- 14 sedentary men with essential hypertension and 10 age-matched normotensive sedentary men.
- Sample size: 24
- Age: HYP 62 +/- 7 years; NORM 60 +/- 8 years
- Sex: Male
- Fitness level: Sedentary
- Health status: Essential hypertension or normotensive; overweight on average

## Methodology

- Non-randomized pre-post intervention study with hypertensive and normotensive groups
- 6 weeks
- Supervised cycling training and laboratory testing
- Controlled study design.

## Protocol

- 10-20-30 cycling HIIT.
- Modality: Stationary cycling.
- Work intervals: 10 s maximal sprint.
- Recovery: 30 s low-intensity plus 20 s moderate-intensity cycling; 3 min passive rest between bouts.
- Sets or repetitions: 2-3 x 5 min bouts.
- Intensity: Low 30-80 W, moderate 50-120 W, maximal sprint >300 W.
- Session duration: Less than 25 min including warm-up.
- Frequency: 2 sessions/week in weeks 1-2, then 3 sessions/week.
- Program length: 6 weeks.
- Progression: Increased from 2 to 3 five-minute bouts and from 2 to 3 weekly sessions.
- Normotensive same-training comparator.
- Modality: Stationary cycling.
- Work intervals: 10 s maximal sprint.
- Recovery: 30 s low plus 20 s moderate cycling; 3 min passive rest.
- Sets or repetitions: 2-3 x 5 min bouts.
- Intensity: Same 10-20-30 cycling protocol.
- Session duration: Less than 25 min including warm-up.
- Frequency: 2 then 3 sessions/week.
- Program length: 6 weeks.
- Progression: Same progression.

## Outcomes

### MSNA
Status: improved
Resting MSNA burst frequency decreased in both hypertensive and normotensive men.

HYP -6 +/- 7 bursts/min; NORM -8 +/- 9 bursts/min; p<0.05, no between-group difference.

### Night BP
Status: improved
Nighttime diastolic and mean arterial BP decreased in hypertensive men only.

HYP DBP -4.0 +/- 6.3 mmHg and MAP -3.5 +/- 6.9 mmHg, p<0.05.

### Body fat
Status: improved
Body mass, visceral fat, and fat percentage decreased in both groups.

Within-group p<0.05; fat-free mass unchanged.

### VO2max
Status: mixed
VO2max increased only in normotensive men; GXT performance improved in both groups.

VO2max group-by-time interaction p<0.05; GXT time improved p<0.01 in both groups.

## Practical Insights

- 10-20-30 cycling concentrates high-intensity work into 100-150 seconds per session.
- Cycling can reduce impact risk for older or clinical-risk users.
- Medication and pathology may blunt VO2max response even when BP and MSNA improve.

## Limitations

- Men only.
- Small sample.
- No randomized non-training control.
- Many hypertensive participants used antihypertensive medication.
- No long-term follow-up.

## Safety And Adherence

- Cycling was chosen to minimize injury risk.
- All training sessions were supervised and heart rate monitored.
- No cohort-specific adverse-event table was found in the reviewed text.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/33013285/) (pubmed)
- [DOI](https://doi.org/10.3389/fnins.2020.00841) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7461859/) (full text)

## Agent Guidance

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