Priming cardiac function with voluntary respiratory maneuvers and effect on early exercise oxygen uptake.

Oxygen uptake (V̇o 2 ) at exercise onset is determined in part by acceleration of pulmonary blood flow ([Formula: see text]). Impairments in the [Formula: see text] response can decrease exercise tolerance. Prior research has shown that voluntary respiratory maneuvers can augment venous return, but the corollary impacts on cardiac function, [Formula: see text] and early-exercise V̇o 2 remain uncertain. We examined 1 ) the cardiovascular effects of three distinct respiratory maneuvers (abdominal, AB; rib cage, RC; and deep breathing, DB) under resting conditions in healthy subjects ( Protocol 1 , n = 13), and 2 ) the impact of pre-exercise DB on pulmonary O 2 transfer during initiation of moderate-intensity exercise ( Protocol 2 , n = 8). In Protocol 1 , echocardiographic analysis showed increased right ventricular (RV) cardiac output and left ventricular (LV) cardiac output (RVCO and LVCO, respectively), following AB (by +23 ± 13 and +18 ± 15%, respectively, P < 0.05), RC (+23 ± 16; +14 ± 15%, P < 0.05), and DB (+27 ± 21; +23 ± 14%, P < 0.05). In Protocol 2 , DB performed for 12 breaths produced a pre-exercise increase in V̇o 2 (+801 ± 254 mL·min -1 over ∼6 s), presumably from increased [Formula: see text], followed by a reduction in pulmonary O 2 transfer during early phase exercise (first 20 s) compared with the control condition (149 ± 51 vs. 233 ± 65 mL, P < 0.05). We conclude that 1 ) respiratory maneuvers enhance RVCO and LVCO in healthy subjects under resting conditions, 2 ) AB, RC, and DB have similar effects on RVCO and LVCO, and 3 ) DB can increase [Formula: see text] before exercise onset. These findings suggest that pre-exercise respiratory maneuvers may represent a promising strategy to prime V̇o 2 kinetics and thereby to potentially improve exercise tolerance in patients with impaired cardiac function. NEW & NOTEWORTHY We demonstrate that different breathing maneuvers can augment both right and left-sided cardiac output in healthy subjects. These maneuvers, when performed immediately before exercise, result in a pre-exercise "cardiodynamic" increase in oxygen uptake (V̇o 2 ) associated with a subsequent reduction in the "cardiodynamic" V̇o 2 normally seen during early exercise. We conclude that pre-exercise breathing maneuvers are a plausible tool worthy of additional study to prime V̇o 2 kinetics and improve exercise tolerance in patients with cardiovascular disease.