Estudio de la difusión pulmonar durante el ejercicio en condiciones extremas

La siguiente tesis doctoral tiene como objetivo principal estudiar la respuesta de la difusión pulmonar en la barrera alveolocapilar durante diferentes condiciones extremas relacionados con el entrenamiento de natación y el ejercicio en altitud. De esta forma, se describirán los siguientes objetivos específicos: 1. Evaluar posibles cambios en la difusión pulmonar (DLCO y KCO) y otros parámetros respiratorios (VA, TLC, VCIN y RV) durante el entrenamiento (pre- vs. post-) en natación y natación artística, además de valorar su posible relevancia clínica. o Describir los parámetros de capacidad pulmonar y de difusión en deportistas acuáticos. 2. Valorar el impacto de una concentración de entrenamiento en altitud a 1.850 m en los parámetros de capacidad pulmonar y difusión de un grupo de nadadores de elite. o Evaluar posibles cambios en la difusión pulmonar después de una sesión de ciclismo a intensidad moderada a 3.000 m de hipoxia normobárica. 3. Comparar la respuesta de difusión pulmonar en un grupo de nadadores de elite vs. un grupo de sujetos sanos durante una exposición aguda a 4.000 m simulados de hipoxia hipobárica y después de un ejercicio de intensidad moderada a dicha altitud.Lung diffusing capacity describes the alveolar-capillary diffusion in the lungs, which increase linearly in relation to cardiac output, and decrease in the presence of lung interstitial disease. This thesis aimed to study whether aquatic exercise (swimming and artistic swimming) provoke a decrease in lung diffusing capacity for carbon monoxide (DLCO) during training; and whether altitude training camp or exercise in a short-term exposure to high-altitude modify lung diffusing capacity in elite swimmers. The first article describes the initial justification of this research. In this report case, we describe the circumstance faced by a female elite swimmers who had repeated dyspnoea associated to the intensity of the swimming exercise. She experimented a post-exercise reduction in spirometric values and the presence of ultrasound lung comets (ULCs), suggesting a swimming-induced pulmonary oedema (SIPO). The report case conclude that the administration of an inhibitor of the carbonic anhydrase (Acetazolamide) solved this condition. The second and third article form two parts of the same research. We conducted a follow-up during 10 swimming training session in 21 elite junior swimmers evaluating the DLCO pre- and post-training. We show a slight decrease in lung diffusing capacity (−2.5%) after training, showing that swimmers experience subclinical decrease in lung diffusing capacity. Also, there were a large inter-individual variability in the response of DLCO to swim training along the follow-up including 6 subjects showing a considerable average decrease (−5.6–11.2%), suggesting that, doctors and coaches should pay attention to the individual changes in alveolar-capillary diffusing capacity among elite swimmers. The fourth article describes the changes in DLCO during an artistic swimming session in 11 artistic swimmers. After the first part of the training (apnoeic swimming) there were an increase in lung diffusing capacity (+9.2%) and later, after the second part (choreography and figures) there were a decrease in lung diffusing capacity regarding to basal condition (−4.0%). Therefore, it could be interesting to monitor carefully individual response to exercise since there occur decreases in DLCO up to 20% after training. The fifth article studies the possible modifications in lung diffusing capacity during a 14-day swimming altitude training camp at 1,850 m. There were no changes in DLCO after the training camp, but a decrease in alveolar volume (VA) and an increase in transfer coefficient of the lung for carbon monoxide (KCO) occur. In contrast to the results found at sea level in the second and third article, a swimming training session in moderate altitude did not change lung diffusing capacity acutely in elite swimmers, but a posterior cycling session at normobaric-simulated 3,000 m reduced DLCO significantly (−10%). The sixth article reports the lung diffusing response to 30-min moderate intensity interval exercise in a short-term exposure to high-altitude (4,000 m) in elite swimmers. There were no changes in DLCO although elite swimmers showed large decrease in SpO2 (72 ± 5 %) and a large increase in HR (139 ± 9 beats·min-1) at the end of the exercise. The seventh article evaluates whether there are changes in alveolar-capillary diffusion after different modalities of exercise, both at sea level (SL) and high-altitude (HA) in 11 healthy subjects. At SL, lung diffusing capacity largely increased after 30-s maximal exercise in a cycle ergometer, although the O2-dependence was small during anaerobic exercise. In contrast, DLCO did not change after 15-min moderate intensity continuous exercise at SL. Later, at HA, and similar to the previous study, an acute protocol of exercise at HA did not modify lung diffusing capacity in healthy subjects, suggesting that short-term exercise modalities at high-altitude are well covered by the functional properties of healthy individuals’ lungs. Lastly, the eighth article describes the pulmonary functional capabilities in elite swimmers, artistic swimmers and water polo players, showing higher lung volumes and diffusing capacity than the reference values by height and age. In this article, we discuss that swimming-based sports could be beneficial to improve the pulmonary function in many different segments of the population (from subjects with chronic pathologies to elite athletes) due to the physical properties of the water and physiological implications of the practice of swimming