Autonomic Nervous System Response During Scuba Diving Activity

In this work, Heart Rate Variability indices are computed to analyze the Autonomic Nervous System response during a scuba diving activity. To do that, electrocardiogram signals from 6 subjects were recorded in a reservoir immersion. Two different stages were analyzed: baseline stage, where subjects remained seated outside the water; and immersion stage, where subjects performed physical activity in a non-controlled environment. The smoothed pseudo Wigner-Ville distribution was used for the time-frequency analysis. Results show a statistically significant increase of the mean heart rate and a significant decrease in the root mean square of the successive normal beats during the immersion stage. However, frequency-domain parameters did not show any significant difference between stages. Whereas time-domain parameters reflect a sympathetic activation during the immersion, caused by the predominance of the physical activity and the stress of the challenging environment, frequency-domain parameters are not able to capture it. Further studies are needed to draw more robust conclusions by increasing the number of subjects and exploring alternative methods to compute the Autonomic Nervous System frequency content.