Erythropoietic responses to a series of repeated maximal dynamic and static apnoeas in elite and non-breath-hold divers

Abstract

Purpose: Serum erythropoietin (EPO) concentration is increased following static apnoea-induced hypoxia. However, the acute erythropoietic responses to a series of dynamic apnoeas in non-divers (ND) or elite breath-hold divers (EBHD) are unknown.

Methods: Participants were stratified into EBHD (n = 8), ND (n = 10) and control (n = 8) groups. On two separate occasions, EBHD and ND performed a series of five maximal dynamic apnoeas (DYN) or two sets of five maximal static apnoeas (STA). Control performed a static eupnoeic (STE) protocol to control against any effects of water immersion and diurnal variation on EPO. Peripheral oxygen saturation (SpO₂) levels were monitored up to 30 s post each maximal effort. Blood samples were collected at 30, 90, and 180 min after each protocol for EPO, haemoglobin and haematocrit concentrations.

Results: No between group differences were observed at baseline (p > 0.05). For EBHD and ND, mean end-apnoea SpO₂ was lower in DYN (EBHD, 62 ± 10%, p = 0.024; ND, 85 ± 6%; p = 0.020) than STA (EBHD, 76 ± 7%; ND, 96 ± 1%) and control (98 ± 1%) protocols. EBHD attained lower end-apnoeic SpO₂ during DYN and STA than ND (p < 0.001). Serum EPO increased from baseline following the DYN protocol in EBHD only (EBHD, p < 0.001; ND, p = 0.622). EBHD EPO increased from baseline (6.85 ± 0.9mlU/mL) by 60% at 30 min (10.82 ± 2.5mlU/mL, p = 0.017) and 63% at 180 min (10.87 ± 2.1mlU/mL, p = 0.024). Serum EPO did not change after the STA (EBHD, p = 0.534; ND, p = 0.850) and STE (p = 0.056) protocols. There was a significant negative correlation (r = - 0.49, p = 0.003) between end-apnoeic SpO₂ and peak post-apnoeic serum EPO concentrations.

Conclusions: The novel findings demonstrate that circulating EPO is only increased after DYN in EBHD. This may relate to the greater hypoxemia achieved by EBHD during the DYN.

Keywords: Breath-hold; Desaturation; Diving response; Erythropoiesis; Erythropoietin; Hypoxia.

Fig. 1

Change in mean EPO (mlU/mL) concentrations from baseline to 180 min post-apnoeas. Data are presented as mean ± SD. Significant difference (p< 0.05) compared to baseline is denoted as asterisk, between dynamic and static apnoea protocols is denoted as double asterisk, between dynamics and control protocols is denoted as dagger. a Static apnoea and control protocols. b Dynamic apnoea and control protocols. EBHD elite breath-hold divers, ND non-divers

Fig. 2

Relationship between end-apnoeic peripheral oxygen saturation levels and peak post-apnoeic serum erythropoietin concentrations for both groups and apnoeic protocols

Fig. 3

Relationship between post-apnoeic delta percentage change for erythropoietin concentrations and plasma volume (a), blood volume (b) and cell volume (c) for both groups and apnoeic protocols