Heart rate profiles and heart rate variability during scuba diving

Abstract

AIMS: The aim of the present study was to describe heart rate profiles and heart rate variability patterns in non-selected scuba divers of different ages under non-experimental real-world conditions. METHODS: We used specially designed silver-loaded polydimethylsiloxane dry electrodes for underwater ECG recordings. With a custom-built setup, heart rate profiles and heart rate variability patterns were documented before submersion, during diving and after resurfacing in 18 separate dives. RESULTS: Heart rates of the divers just before descent were remarkably high (median 114 bpm, interquartile range [IQR] 83–154) with a statistically significant rapid decrease after submersion (median 90 bpm, IQR 70–116; p = 0.008). The percentage heart rate reduction by submersion was individually very variable (median 21%, range 5–39%). We noted a general increase in autonomic nervous system (ANS) activity without predominance of parasympathetic parameters, suggesting a concomitant sympatheticadrenergic activation. CONCLUSIONS: Scuba diving under real-world conditions by non-selected divers is characterised by relatively high heart rates just before submersion, an individually variable but significant bradycardic dive response, and induces an immediate and sustained parallel increase of parasympathetic and sympathetic-adrenergic autonomic nervous system activity. These observations could explain several specific pathophysiological mechanisms of diving incidents (haemodynamic decompensation, arrhythmias, acute coronary syndromes) and underlines the importance of cardiovascular risk stratification in diving eligibility assessment.

The diving response and cardiac vagal activity: A systematic review and meta‐analysis

“…One of the included trials tested the effect of facial immersion (Al Haddad et al, 2010) of facial cooling (Schlader et al, 2016), two of forehead cooling (Jarczok et al unpublished, DRKS00016597) (Ruschil et al, 2021) and 12 of total body immersion (Berry et al, 2017; Chouchou et al, 2009; Costalat et al, 2015; Lundell et al, 2019; Lundell et al, 2021; Noh et al, 2018; Schaller et al, 2021; Schipke & Pelzer, 2001; Schirato et al, 2018; Solana‐Tramunt et al, 2019; Vicente‐Rodríguez et al, 2020; Weist et al, 2012). Two trials tested immersion combined with apnea (Costalat et al, 2015; Vicente‐Rodríguez et al, 2020), two with snorkel breathing (Al Haddad et al, 2010; Schipke & Pelzer, 2001), and nine trials tested the effect of SCUBA diving (Berry et al, 2017; Lundell et al, 2019; Lundell et al, 2021; Noh et al, 2018; Schaller et al, 2021; Schipke & Pelzer, 2001; Schirato et al, 2018; Weist et al, 2012). Another five studies did not use any breathing device or aid (Jarczok et al unpublished, DRKS00016597) (Louis et al, 2015; Ruschil et al, 2021; Schlader et al, 2016; Solana‐Tramunt et al, 2019).…”

“…Another five studies did not use any breathing device or aid (Jarczok et al unpublished, DRKS00016597) (Louis et al, 2015; Ruschil et al, 2021; Schlader et al, 2016; Solana‐Tramunt et al, 2019). Nine studies used cold water, ice bags or in one case cryostimulation to induce the diving reflex (Jarczok et al unpublished, DRKS00016597) (Al Haddad et al, 2010; Louis et al, 2015; Lundell et al, 2019; Lundell et al, 2021; Noh et al, 2018; Ruschil et al, 2021; Schaller et al, 2021; Schlader et al, 2016), whereas the other seven used water above 15°C (Berry et al, 2017; Chouchou et al, 2009; Costalat et al, 2015; Schipke & Pelzer, 2001; Solana‐Tramunt et al, 2019; Vicente‐Rodríguez et al, 2020; Weist et al, 2012). In three studies, the exposure condition was dynamic (Chouchou et al, 2009; Solana‐Tramunt et al, 2019; Vicente‐Rodríguez et al, 2020).…”

Depth of SCUBA Diving Affects Cardiac Autonomic Nervous System

“…The most interesting observation in our work was the rapid recovery of HRV parameters after surfacing. Still, it is to be remembered that the results of HRV are influenced by multiple factors like basal heart rate, a stressful life, and the presence of positive cardiovascular risk factors [ 16 , 17 , 18 ]. On the other hand, recovery after HRV measures can differ depending on personal adaptational processes, the consumption of food and beverages that can trigger HRV activity, muscle mass management, level of condition, etc.…”

“…On the other hand, recovery after HRV measures can differ depending on personal adaptational processes, the consumption of food and beverages that can trigger HRV activity, muscle mass management, level of condition, etc. [ 16 , 17 , 18 ]. Since there was a rise in LF after surfacing, we suggest that the sympathetic activity changed during dives, and its effect on various body regions should be the subject of further investigations.…”