Preterm birth can significantly impair the functional and anatomical development of the respiratory system, especially respiratory regulation, and can set the stage for several lifelong medical sequelae. Prematurity is associated with changes in the hypercapnic response in adulthood (respiratory response to elevated CO2). The altered respiratory response to CO2 could have an impact on free diving. A study investigated the proportion of former preterm subjects among elite freedivers - and found amazing results.
The best freedivers in the world (according to the AIDA ranking for 2016-2021) were asked about their date of birth using a questionnaire. Of the 146 participants, a total of 17.1% were born prematurely, of which 13.7% were moderately premature (32-37 weeks of pregnancy) and 3.4% very premature (before 32 weeks of pregnancy). These figures are twice as high as in the general population (8.5%, estimated based on the geographical origin of the divers).
However, there was no difference in the diving performance of premature and full-term subjects.
The question arises as to whether prematurity and the associated changes in the breathing response to the partial pressure of CO2 offer an advantage for freediving and whether the proportion of former premature subjects at the top of the freediving world is therefore higher. It is speculated that a reduced sensitivity to CO2 could offer an advantage in this respect, i.e. that former premature athletes can hold their breath longer because the respiratory drive of CO2 is weakened. The question is open, as there are also study results that point in the opposite direction, in that former premature borns have a higher sensitivity to CO2, which would put them at a disadvantage in terms of breath holding.
In addition to breath-holding, other changes in physiological responses that enable longer apnea dives could also be considered. Data from altitude medicine show that the sensitivity of the baroreflex, which aims to maintain arterial blood pressure via strain receptors in the carotid and aorta, is weakened under hypoxia in former preterm but otherwise healthy adults compared to full-term subjects, especially under hypercapnia (elevated CO2). This is an indicator that prematurity can have a profound effect on vegetative regulation well into adulthood. The extent to which this results in an advantage for free diving remains to be seen.
The findings of the study are undoubtedly remarkable, even if the sample is small from an epidemiological point of view. It is unlikely to be due to chance, even if the reasons for this remain unclear.
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