Acute apnea is known to induce decreases in oxyhemoglobin desaturation (SpO2) and increases in erythropoietin concentration ([EPO]). This study examined the potential of an apnea training program to induce erythropoiesis and increase hematological parameters and exercise performance. Twenty-two male subjects were randomly divided into an apnea and control group. The apnea group performed a 6-wk apnea training program consisting of a daily series of five maximal static apneas. Before and after training, subjects visited the lab on 3 test days to perform 1) a ramp incremental test measuring V̇o2peak, 2) CO-rebreathing for Hbmass determination and a 3-km time trial, and 3) an apnea test protocol with continuous finger SpO2 registration. Venous blood samples were drawn before and 180 min after the apnea test for analysis of [EPO]. Minimal SpO2 reached during the apnea test protocol was 91 ± 7% pre and 82 ± 7% post apnea training. The apnea test protocol did not elicit an acute increase in [EPO] (P = 0.685) before nor after the training program. Consequently, resting [EPO] (P = 0.170), Hbmass (P = 0.134), V̇o2peak (P = 0.796), and 3-km cycling time trial performance (P = 0.509) were not affected either. The apnea test and training protocol, consisting of five maximal static apneas, did not induce a sufficiently strong hypoxic stimulus to cause erythropoiesis and therefore did not result in an increase in resting [EPO], Hbmass, V̇o2peak, or time trial performance. Longer and/or more intense training sessions inducing a stronger hypoxic stimulus are probably needed to obtain changes in hematological and exercise parameters.NEW & NOTEWORTHY Apnea training has been suggested as a promising method to improve exercise performance for over a decade. However, to our knowledge, this study is the first to evaluate its value on both hematological parameters and exercise performance, including Hbmass and a control group. No changes in Hbmass nor exercise performance were observed. Contradicting previous research, no acute increase in [EPO] following apnea was observed either, indicating that more intense protocols are needed, at least in nonapnea-trained individuals.
Keywords: apnea training; desaturation; erythropoietin; hemoglobin mass; performance.