Spleen emptying does not correlate with faster oxygen kinetics during a step-transition supine cycling

This manuscript quantified spleen volume changes and examined the relationship between those changes and oxygen uptake kinetics during supine cycling. Ten volunteers (age = 22 ± 3), completed 3 step transitions from 20 W to their power output at 90% gas exchange threshold. Ultrasonic measurements of the spleen were performed each minute. The largest spleen volume reduction was 105 mL (p = 0.001). No associations existed between i) spleen volumes at rest; and ii) spleen volume changes (%) and tau pulmonary oxygen uptake (τV̇O_2p). Larger resting spleen volume and greater emptying do not correlate with a faster τV̇O_2p. Novelty: Greater splenic contractions do not augment τV̇O_2p, irrespective of spleen emptying and subsequent erythrocyte release.