# Effects of high-intensity interval training and moderate-intensity continuous training on the functioning of attentional networks and heart rate variability in healthy young adults

PMID: 40470031
Journal: Journal of Exercise Science and Fitness
Published: 2025-05-03
Authors: Yue T, Li F, Wang Y

## Question

How do acute HIIT and moderate continuous cycling affect alerting, orienting, executive control, and HRV in healthy young adults?

## Summary

In 36 healthy college students, a single cycling HIIT session improved overall reaction time and executive-control performance on an attention-network task compared with rest and, for executive control, compared with moderate continuous exercise. However, HIIT also reduced the phasic alerting score versus rest and did not improve orienting. HRV reductions suggested stronger arousal/parasympathetic withdrawal after HIIT, which correlated with alerting and executive-control changes.

## Population

- Healthy college students without regular exercise habits.
- Sample size: 36
- Age: 22.0 +/- 3.0 years
- Sex: 14 male, 22 female
- Fitness level: Without regular exercise habits; mean VO2peak 31.7 +/- 6.6 ml/kg/min
- Health status: Healthy, nonsmoking, right-handed, without cardiovascular disease or relevant visual/auditory/reading/mental-health exclusions

## Methodology

- Randomized within-subject crossover acute experiment
- Single acute session per condition with at least 1 week washout
- Laboratory cycle ergometer
- Randomized and controlled study design.

## Protocol

- Acute cycling HIIT.
- Modality: Cycle ergometer.
- Work intervals: 1 minute at 100% Wpeak.
- Recovery: 1 minute active recovery at 20% Wpeak.
- Sets or repetitions: 10 intervals.
- Intensity: 100% Wpeak, approximately 90% HRmax, with recovery at 20% Wpeak.
- Session duration: 20 minutes HIIT plus 2-minute warm-up and 2-minute cool-down.
- Frequency: Single acute session.
- Program length: Single session in crossover protocol.
- Progression: Not applicable.
- MICT and resting control.
- Modality: Cycle ergometer or seated rest.
- Work intervals: MICT continuous cycling for 30 minutes at 40% Wpeak.
- Recovery: Not interval-based; rest condition involved sitting on ergometer.
- Sets or repetitions: MICT: continuous 30 minutes; CON: 24 or 34 minutes seated rest counterbalanced.
- Intensity: MICT at 40% Wpeak, approximately 70% HRmax.
- Session duration: MICT 30 minutes plus 2-minute warm-up and 2-minute cool-down.
- Frequency: Single acute session per condition.
- Program length: Crossover sessions separated by at least 1 week.
- Progression: Not applicable.

## Outcomes

### Overall ANT-I reaction time
Status: improved
HIIT produced faster overall RTs than rest.

Exercise main effect p=.003; HIIT vs CON p=.003.

### Alerting function
Status: worse/safety concern
HIIT reduced phasic alerting function compared with rest.

p=.017, Cohen d=.42.

### Orienting function
Status: no clear change
Neither HIIT nor MICT significantly changed orienting function.

Exercise main effect p=.138.

### Executive control
Status: improved
HIIT improved executive control compared with both MICT and rest.

HIIT vs MICT p=.002, d=.57; HIIT vs CON p=.001, d=.62.

### HRV
Status: mixed
HIIT produced greater immediate and task-related reductions in LnRMSSD and LnHF than MICT and rest.

LnRMSSD and LnHF exercise effects p<.001.

### HRV correlations
Status: mixed
After HIIT, LnRMSSD changes correlated with alerting and executive-control functions.

Immediate LnRMSSD with alerting r=.554, p=.001; with executive control r=.412, p=.016; task-related r=.424 and r=.356.

## Practical Insights

- Acute HIIT may sharpen some executive-control performance but can also change alerting/vigilance dynamics.
- Cognition effects are domain-specific; do not frame HIIT as globally improving attention.
- Arousal and recovery timing matter when placing HIIT before cognitively demanding tasks.

## Limitations

- Acute single-session design.
- Healthy young adults only.
- Mechanisms inferred from HRV only; no biochemical markers.
- Laboratory cycling protocol may not transfer to bodyweight HIIT.
- No long-term attention outcomes.

## Safety And Adherence

- No adverse events were reported in the extracted text.
- Participants completed health screening and were excluded for cardiovascular disease, smoking, mental illness history, and other factors.
- HRV data for two participants were missing because of equipment malfunction.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/40470031/) (pubmed)
- [DOI](https://doi.org/10.1016/j.jesf.2025.04.003) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12135363/) (full text)

## Agent Guidance

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