[Arrhythmia and vago-sympathetic equilibrium in athletic divers]

Area of Science:

• Cardiology
• Sports Physiology
• Environmental Medicine

Context:

• Athletic divers undergo unique physiological stresses during underwater activities.
• Electrocardiographic (ECG) monitoring provides insights into cardiac responses during diving.
• Diving environments, whether artificial or natural, may elicit different physiological adaptations.

Purpose:

• To investigate the cardiac electrophysiological responses of athletic divers during two distinct diving conditions.
• To compare the effects of apnoea-only diving in a controlled environment versus mixed apnoea and aqualung diving in a natural setting.
• To determine the correlation between diving experience and observed cardiac changes, specifically bradycardia.

Summary:

• Holter monitoring in 16 athletic divers revealed distinct heart rate patterns.
• Apnoeic dives, especially in a 28°C, 15m tank, induced marked and prolonged bradycardia, more so than in natural environments.
• Bradycardia severity correlated significantly with diver experience (r=0.90).
• Atrial and/or ventricular extrasystoles accompanied bradycardia in 70% of artificial environment dives.
• Tachycardia was more prevalent in natural environments, peaking during aqualung exercises.
• These findings suggest a shift in autonomic nervous system balance and its electrophysiological consequences during diving.

Impact:

• Provides crucial data on the cardiovascular strain experienced by athletic divers.
• Highlights the influence of environmental factors and diving techniques on cardiac function.
• Informs safety protocols and training regimens for divers by elucidating physiological responses.
• Contributes to understanding the autonomic nervous system's adaptation to breath-hold and scuba diving.