Why the study?
Does moderate upright ergometer exercise compared to supine exercise alter cardiac performance measures?
Does moderate upright ergometer exercise compared to supine exercise alter cardiac performance measures?
Posture during exercise significantly alters cardiac performance indices, with upright exercise suggesting an additional Frank-Starling effect compared to supine exercise.
Posture must be accounted for when interpreting exercise cardiac indices; leaves open effects on outcomes and need for standardized protocols.
Because posture significantly influences cardiac performance, the effects of moderate supine and upright ergometer exercise were compared on the basis of proportional (+37%) rate increments over resting control. Supine exercise produced significant decreases in left ventricular ejection time (LVET), pre-ejection period (PEP), and isovolumic contraction time (IVCT). Ejection time index (ETI) and "corrected ejection time" (LVETc) did not change significantly. Upright exercise produced greater decreases in PEP and LVET, but despite the rate increase there was no change in LVET, which resulted in sharp increases in ETI and LVETc. The discordant directional effects on LVET and its rate-correcting indices between the two postures were consistent with hemodynamic studies demonstrating lack of stroke volume change during supine exercise and increased stroke volume over control during light to moderate upright exercise. Concordant effects on PEP and IVCT are consistent with the inotropic effect of exercise in both postures with an additional Frank-Starling effect postulated during upright exercise.
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Spodick et al. (1973) studied this question.
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