Effects of two weeks of daily apnea training on diving response, spleen contraction, and erythropoiesis in novel subjects

Three potentially protective responses to hypoxia have been reported to be enhanced in divers: (1) the diving response, (2) the blood‐boosting spleen contraction, and (3) a long‐term enhancement of hemoglobin concentration (Hb). Longitudinal studies, however, have been lacking except concerning the diving response. Ten untrained subjects followed a 2‐week training program with 10 maximal effort apneas per day, with pre‐ and posttraining measurements during three maximal duration apneas, and an additional post‐training series when the apneic duration was kept identical to that before training. Cardiorespiratory parameters and venous blood samples were collected across tests, and spleen diameters were measured via ultrasound imaging. Maximal apneic duration increased by 44 s (P