Scientific news

Several studies have reported a blunted hypercapnic ventilatory response (HCVR) in trained breath hold divers. A study investigated whether repeated apneas with short intervals reduces the HCVR. Although the breath hold time increased by 43% during the series of apneas, the slope of the HCVR test was not affected (1), which shows that the increased breath hold time cannot be explained by a reduced HCVR.

Using magnetic resonance imaging, a study demonstrated that filling of sinuses and middle ear cavities by one diver (Patrick Musimu) by simply pouring water in the nose is possible(1). He managed to do that without any noticeable reflex reaction (sneezing, coughing), pain or discomfort. This confirms that it is possible to relax the Eustachian tube orifice sufficiently for water to passively enter the retrotympanic spaces. The most obvious risk associated with this technique is infections due to possible pathogens in the water. However, Patrick Musimu never had symptoms of sinusitis or middle ear infection, not even in the beginning of him using this technique (2).

A study performed on elite swimmers showed that glossopharyngeal pistoning (GP) performed four times a week for 5 wk increased chest expansion significantly during the training period. The buoyancy lifting force increased significantly by 0.17 and 0.37 kg for the males and the females, respectively. The females also increased their vital capacity significantly by 2%. They concluded the lung volumes and buoyancies of swimmers can be increased by sessions of GP (3)

A study performed by P.Lindholm et al. showed that breath hold diving on empty lungs to shallow depths can induce hemoptysis (The expectoration of blood or of blood-streaked sputum from the larynx, trachea, bronchi, or lungs) and possibly edema in the lower airways in healthy subjects (4). The study was performed on subjects who dived to 6m on empty lungs or after glossopharyngeal exsufflation.
Another study by Liner MH & Andersson JP performed during an international freediving competition showed that 12 of 19 subjects which participated in the study and performed dives to depths of 25-75 meters had signs of pulmonary edema (5). The average reductions in forced vital capacity (FVC) and forced expiratory volume in the first second (FEV1) were - 9% and -12%, respectively, after deep dives compared to after pool dives. In addition, the average reduction in arterial oxygen saturation (SaO2) was -4% after the deep dives(5)