Respiratory muscle strength pre- and post-maximal apneas in a world champion breath-hold diver.

Maximal static dry, that is, on land, apneas (breath-holds) result in severe hypoxemia and hypercapnia and have easy-going and struggle phases. During the struggle phase, the respiratory muscles involuntarily contract against the closed glottis in increasing frequency and magnitude, that is, involuntary breathing movements (IBMs). IBMs during maximal static apnea have been suggested to fatigue respiratory muscles, but this has yet to be measured. Thus, the purpose of this study was to quantify respiratory muscle strength pre- and post-apneas in an elite, world champion, world record-holding apneist. To do so, maximal inspiratory and expiratory pressure maneuvers (MIP and MEP, respectively) were performed pre- and post-apnea protocol, which included three preparatory apneas with 2.5-min rest. All preparatory apneas were ended after the participant reported 7-10 IBMs. Next, he performed three maximal static dry apneas with 5-min rest in between. The participant had maximal apneas lasting 363, 408, and 460 s. Including preparatory apneas, the participant's total apnea duration was 33.4 min in 57.0 min. Following the apnea protocol, that is, pre versus post, there was no change in MIP (-124.2 vs. -123.6 cmHO) or MEP (259.4 vs. 262.5 cmHO). These data, albeit in a single individual, suggest that respiratory muscle strength is not impacted by maximal static breath-holds. This could be the result of training and/or be a feature of this individual that allows him to excel in this sport. Previous work has suggested that respiratory muscle fatigue may result from maximal breath-holds but this has not been measured. We measured respiratory muscle strength pre- and post-maximal apneas in a world champion breath-hold diver. We found no change in respiratory muscle strength following a series of apneas. This may be an adaptation of the diver's training or a feature of their physiology that allows them to be successful in this physiologically challenging sport.