What is the clinical evidence from this study?

Study design: Cross-Sectional. Population: Healthy young adults (n=35). Intervention: Aerobic fitness (VO2max). Primary outcome: Correlation between VO2max and high frequency (HF) power (r=0.450, p=0.006).

What question did this study set out to answer?

This study aims to investigate how aerobic fitness levels affect cardio-vagal adaptation in young adults.

June 16, 2026Open Access

Effect of Aerobic Fitness on Cardio-Vagal Adaptation

Key Result

Higher aerobic fitness (VO2max) was significantly correlated with higher parasympathetic activity, indicated by a positive correlation with HF power (r=0.450, p=0.006).

Key Points

This study aims to investigate how aerobic fitness levels affect cardio-vagal adaptation in young adults.
Thirty-five physically active university students participated.
VO₂ max assessed via a graded treadmill test and HRV measured through ECG.
Statistical analysis involved Pearson’s correlation with Bonferroni adjustment.
No significant correlations with time-domain HRV indices (SDNN, pNN50, NN50).
RMSSD showed a weak to moderate positive association (r=0.340, p=0.045).
Significant correlations with frequency-domain indices: HF power (r=0.450, p=0.006), LF power (r=-0.450, p=0.006), and LF/HF ratio (r=-0.449, p=0.006).

Study Design

Type

Cross-Sectional (n=35)

Multicenter

Structured PICO

Does aerobic fitness correlate with improved cardio-vagal adaptation (HRV indices) in physically active young adult males?

Population

35 healthy, physically active young adult males with at least four years of regular exercise participation were assessed in a cross-sectional study to evaluate the relationship between aerobic fitness and heart rate variability.

Exposure

Aerobic fitness (VO₂ max) assessed using a graded treadmill test (Bruce Protocol)

Outcome

Correlation between VO₂ max and heart rate variability (HRV) indices (time-domain and frequency-domain)surrogate

Higher aerobic fitness (VO₂ max) is significantly associated with enhanced parasympathetic modulation and improved cardio-autonomic balance in physically active young adult males.

Main Result

Effect estimate: r=0.450

p-value: p=0.006

Limitations

Only male young adult participants were included
Small sample size
Lack of long-term HRV monitoring
Did not include elite athletes from various sports backgrounds

Abstract

Introduction: Maximal oxygen consumption (VO₂ max) and heart rate variability (HRV) are important physiological indicators of both cardiovascular fitness and autonomic nervous system regulation in exercise science. This study aimed to examine the effect of aerobic fitness on cardio-vagal adaptation in young adults. Methods: Thirty-five physically active university students (23.89±1.64 years), with a minimum of four years of regular exercise participation were included in this study. VO₂ max was assessed using a graded treadmill test and HRV indices were obtained from ECG recordings using LabScribe and Kubios software. Pearson’s correlation with Bonferroni-adjusted was performed for statistical analysis. Results: No significant correlations were observed between VO₂ max and time-domain HRV indices SDNN(r=0.177, p=0.309); pNN50(r=0.198, p=0.254) and NN50(r=-0.340, p=0.846), while RMSSD(r=0.340, p=0.045) showed weak to moderate positive association. In contrast, significant correlations were found with frequency-domain indices, including HF power (r=0.450, p=0.006) and LF power (r=-0.450, p=0.006) and LF/HF ratio (r=- 0.449, p=0.006). Conclusion: These findings indicate that regular aerobic exercises associated with improved parasympathetic modulation and enhanced cardio-autonomic balance in young adults.

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