Heart Rate Variability After Blood Flow Restriction Resistance Exercise and Traditional Resistance Exercise in...

Area of Science:

• Exercise Physiology
• Autonomic Nervous System Function
• Cardiovascular Regulation

Background:

• Autonomic nervous system (ANS) responses to exercise are crucial for recovery and adaptation.
• Previous research indicates attenuated ANS responses to blood flow restriction (BFR) resistance exercise in men, but women's responses remain understudied.
• Heart rate variability (HRV) is a non-invasive measure of ANS activity.

Purpose of the Study:

• To compare the acute effects of a single BFR resistance exercise session versus a traditional resistance exercise (TRE) session on HRV in trained men and women.
• To investigate potential sex-specific differences in autonomic responses to BFR and TRE.

Main Methods:

• Thirty-nine trained adults (20 men, 19 women) participated in a randomized, counterbalanced study.
• Participants completed two separate exercise sessions: BFR (30% 1RM, 30-15-15-15 repetitions) and TRE (70% 1RM, 4 sets x 10 repetitions), with 60 seconds rest between sets.
• Resting electrocardiograms were recorded pre- and post-exercise to analyze HRV indices, including normalized low frequency (LF) and high frequency (HF), and the LF/HF ratio.

Main Results:

• Both BFR and TRE increased sympathetic activity (increased LF, increased LF/HF) and decreased parasympathetic activity (decreased HF) as measured by HRV.
• The changes in HRV indices were generally attenuated with BFR compared to TRE across both sexes.
• A significant sex-by-time interaction was observed for the LF/HF ratio, with men exhibiting a greater post-exercise increase in sympathetic dominance compared to women, irrespective of exercise type.

Conclusions:

• Both BFR and TRE elicit changes in autonomic activity, with BFR demonstrating a potentially less stressful autonomic response compared to TRE.
• These findings suggest that BFR resistance exercise may offer a viable training modality with potentially beneficial applications for exercise recovery by reducing autonomic stress.
• Men demonstrate a more pronounced shift towards sympathetic dominance post-exercise compared to women, regardless of the resistance training method employed.