Blood flow restriction training and the exercise pressor reflex: a call for concern

Area of Science:

• Exercise Physiology
• Cardiovascular Physiology
• Rehabilitation Science

Background:

• Blood flow restriction (BFR) training, also known as Kaatsu training, is increasingly used to enhance muscle mass and strength during resistance exercise.
• BFR involves mechanical restriction of blood flow using cuffs, leading to metabolite accumulation and simulating high-intensity exercise benefits with low-intensity protocols.
• This technique is suggested for elderly individuals, injury recovery, and cardiac rehabilitation, but its cardiovascular safety is not fully understood.

Purpose of the Study:

• To review the mechanisms of the autonomic cardiovascular response to exercise with BFR.
• To highlight the missing understanding of the exercise pressor reflex (EPR) in BFR training.
• To raise concerns about the safety of BFR training, particularly for individuals with cardiovascular conditions.

Main Methods:

• Literature review of studies on BFR training and the exercise pressor reflex (EPR).
• Analysis of the physiological responses to BFR, including metabolite accumulation and autonomic nervous system activation.
• Examination of potential cardiovascular risks associated with BFR, especially in diseased populations.

Main Results:

• Reductions in blood flow during exercise engage the EPR, influencing cardiovascular response.
• The EPR's contribution to BFR-mediated cardiovascular responses is largely unexamined in scientific literature.
• Exaggerated sympathetic nerve activity in conditions like hypertension (HTN), heart failure (HF), and peripheral artery disease (PAD) raises concerns for BFR safety in these populations.

Conclusions:

• Abnormal BFR-induced and EPR-mediated cardiovascular responses could lead to adverse events like cardiac arrhythmia, myocardial infarction, or stroke.
• Altered EPR function in HTN, HF, and PAD necessitates caution regarding BFR implementation in cardiovascular rehabilitation.
• Even healthy individuals may face risks from BFR training, indicating a need for more research before widespread adoption or prescription.