Diving in the Arctic : Cold Water Immersion’s Effects on Heart Rate Variability in Navy Divers
Lundell, Richard V.; Räisänen-Sokolowski, Anne K.; Wuorimaa, Tomi K.; Ojanen, Tommi; Parkkola, Kai I. (2020)
Lundell, Richard V.
Räisänen-Sokolowski, Anne K.
Wuorimaa, Tomi K.
Ojanen, Tommi
Parkkola, Kai I.
2020
Tiivistelmä
Introduction: Diving close to the Arctic circle means diving in cold water regardless of
the time of year. The human body reacts to cold through autonomous nervous system
(ANS)-mediated thermoregulatory mechanisms. Diving also induces ANS responses as
a result of the diving reflex.
Materials and Methods: In order to study ANS responses during diving in Arctic water
temperatures, we retrospectively analyzed repeated 5-min heart rate variability (HRV)
measures and the mean body temperature from dives at regular intervals using naval
diving equipment measurement tests in 0◦C water. Three divers performed seven dives
without physical activity (81–91 min), and two divers performed four dives with physical
activity after 10 min of diving (0–10 min HRV recordings were included in the study).
Results: Our study showed a significant increase in parasympathetic activity (PNS) at
the beginning of the dives, after which PNS activity decreased significantly (measure
5–10 min). Subsequent measurements (15–20 min and onward) showed a significant
increase in PNS activity over time.
Conclusion: Our results suggest that the first PNS responses of the human diving reflex
decrease quickly. Adverse effects of PNS activity should be considered on long and
cold dives. To avoid concurrent sympathetic (SNS) and PNS activity at the beginning
of dives, which in turn may increase the risk of arrhythmia in cold water, we suggest
a short adaptation phase before physical activity. Moreover, we suggest it is prudent
to give special attention to cardiovascular risk factors during pre-dive examinations for
cold water divers.
Keywords: diving reflex, diving response, sympathetic response, parasympathetic response, Arctic diving, cold water immersion
the time of year. The human body reacts to cold through autonomous nervous system
(ANS)-mediated thermoregulatory mechanisms. Diving also induces ANS responses as
a result of the diving reflex.
Materials and Methods: In order to study ANS responses during diving in Arctic water
temperatures, we retrospectively analyzed repeated 5-min heart rate variability (HRV)
measures and the mean body temperature from dives at regular intervals using naval
diving equipment measurement tests in 0◦C water. Three divers performed seven dives
without physical activity (81–91 min), and two divers performed four dives with physical
activity after 10 min of diving (0–10 min HRV recordings were included in the study).
Results: Our study showed a significant increase in parasympathetic activity (PNS) at
the beginning of the dives, after which PNS activity decreased significantly (measure
5–10 min). Subsequent measurements (15–20 min and onward) showed a significant
increase in PNS activity over time.
Conclusion: Our results suggest that the first PNS responses of the human diving reflex
decrease quickly. Adverse effects of PNS activity should be considered on long and
cold dives. To avoid concurrent sympathetic (SNS) and PNS activity at the beginning
of dives, which in turn may increase the risk of arrhythmia in cold water, we suggest
a short adaptation phase before physical activity. Moreover, we suggest it is prudent
to give special attention to cardiovascular risk factors during pre-dive examinations for
cold water divers.
Keywords: diving reflex, diving response, sympathetic response, parasympathetic response, Arctic diving, cold water immersion
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