Generalized Response of the Exercise Pressor Reflex

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Autonomic responsiveness to reflex stimuli varies considerably between individuals, with implications for predicting cardiovascular disease. PURPOSE: To standardize blood pressures to activation of the exercise pressor reflex using isometric handgrip exercise followed by post-exercise circulatory arrest (PECA). METHODS: Using specific search terms including “metaboreflex”, “ergoreflex”, “handgrip”, “reflex”, “static”, and “isometric”, we identified 151 studies that quantified the pressor response to handgrip exercise followed by PECA in healthy humans aged 19-44 years. We characterized these studies by exercise mode (static vs. dynamic), percentage of maximum voluntary contraction, blood pressure measurement technique, duration of exercise, duration of PECA, and method of data presentation (absolute values vs. changes from baseline). Preliminary analysis revealed distinct effects of exercise intensity and duration. We constrained further analysis to studies including healthy adults completing isometric handgrip exercise at 30-33% of maximum for 3 minutes and 2 or more minutes of PECA, with blood pressure measured from the wrist or finger of the resting arm (total of 4 studies). RESULTS: Using the reported means and variation we employed bootstrapping with weighted re-sampling (n=10,000) to create a statistically comparable normal distribution of responses. Based on these criteria, the average population mean arterial pressure response for the second minute of PECA is 19 mmHg. The first quartile response is 13 mmHg, and the third quartile is 26 mmHg. CONCLUSIONS: The autonomic response following ischemic handgrip varies considerably between individuals, even when experimental conditions are standardized. The possible foundation for these differences may be neural (e.g., afferent, central, or efferent) or extra-neural (e.g., genetic, muscle fiber type, or vascular).