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Acute effects of apnea bouts on hemoglobin concentration and hematocrit: a systematic review and meta-analysis. New!

Omar López-Rebenaque, PT, MSc1; Luis Solís-Ferrer, PT, MSc1; José Fierro-Marrero, PT, MSc1,2; Francisco de Asís-Fernández, PT, PhD1,3

  1. 1  Departamento de Fisioterapia, Facultad de Ciencias de la Salud, Centro Superior de Estudios Universitarios La Salle, Universidad Autónoma de Madrid, Spain

  2. 2  Motion in Brains Research Group, Departamento de Fisioterapia, Centro Superior de Estudios Universitarios La Salle, Universidad Autónoma de Madrid, Aravaca, Madrid, Spain.

  3. 3  Breatherapy Research Group, Centro Superior de Estudios Universitarios La Salle, Universidad Autónoma de Madrid, Spain.

CORRESPONDING AUTHOR: José Fierro-Marrero – jose.fierromarrero@yahoo.com

ABSTRACT

López-Rebenaque O, Solís-Ferrer, Fierro-Marrero J, Asís-Fernández F. Acute effects of apnea bouts on hemoglobin concentration and hematocrit: a systematic review and meta-analysis. Undersea Hyperb Med. 2024 Second Quarter; 51(2):173-184.

Objective: This study aimed to systematically analyze the existing literature and conduct a meta-analysis on the acute effects of apnea on the hematological response by assessing changes in hemoglobin (Hb) concentration and hematocrit (Hct) values.

Methods: Searches in Pubmed, The Cochrane Library, and Web of Science were carried out for studies in which the main intervention was voluntary hypoventilation, and Hb and Hct values were measured. Risk of bias and quality assessments were performed.

Results: Nine studies with data from 160 participants were included, involving both subjects experienced in breath-hold sports and physically active subjects unrelated to breath-holding activities. The GRADE scale showed a “high” confidence for Hb concentration, with a mean absolute effect of 0.57 g/dL over control interventions. “Moderate” confidence appeared for Hct, where the mean absolute effect was 2.45% higher over control interventions. Hb concentration increased to a greater extent in the apnea group compared to the control group (MD = 0.57 g/dL [95% CI 0.28, 0.86], Z = 3.81, p = 0.0001) as occurred with Hct (MD = 2.45% [95% CI 0.98, 3.93], Z = 3.26, p = 0.001).

Conclusions: Apnea bouts lead to a significant increase in the concentration of Hb and Hct with a high and moderate quality of evidence, respectively. Further trials on apnea and its application to different settings are needed.

Keywords: apnea; exercise; hematocrit; hemoglobin; hypoventilation; hypoxia

DOI:10.22462/627