TY - JOUR
T1 - Diurnal variation in the diving bradycardia response in young men
AU - Konishi, Masayuki
AU - Kawano, Hiroshi
AU - Xiang, Mi
AU - Kim, Hyeon Ki
AU - Ando, Karina
AU - Tabata, Hiroki
AU - Nishimaki, Mio
AU - Sakamoto, Shizuo
N1 - Funding Information:
Heartfelt thanks are due to the subjects who participated in this study and their guardians. This study was supported by The Ministry of Education, Science, Sports and Culture of Japan under grant (Grant Nos. 25560376 and 26750340).
Publisher Copyright:
© 2016, Springer-Verlag Berlin Heidelberg.
PY - 2016/4/1
Y1 - 2016/4/1
N2 - Purpose: The present study aimed to examine diurnal variation of the diving bradycardia responses on the same day. Methods: Eighteen young men (age 26 ± 2 years; height 174.2 ± 6.0 cm; body mass 70.2 ± 8.1 kg; body fat 18.0 ± 3.8 %; mean ± standard deviation) participated in this study. Oral temperature, heart rate variability (HRV) from 5-min of electrocardiogram data, and diving bradycardia responses were measured at 0900, 1300, and 1700 hours daily. All participants performed diving reflex tests twice in the sitting position with the face immersed in cold water (1.9–3.1 °C) and apnea at midinspiration for a minimum of 30 s and as long as possible, in consecutive order. Results: Oral temperature was found to be less in the morning (0900) than in the afternoon (1300) and evening (1700). In the frequency domain parameters of heart rate variability, the natural logarithms of high-frequency power were higher in the morning than in the evening. All participants showed bradycardia response to the two diving reflex tests. The peak values of R–R interval during the diving reflex test both for as long as possible and 30 s were longer in the morning than in the afternoon and evening. Conclusion: Our results indicated that the maximal bradycardia during the diving reflex test exhibits a diurnal variation, with peak levels at morning and gradual decrease towards the evening. The HRV indexes show the same variation.
AB - Purpose: The present study aimed to examine diurnal variation of the diving bradycardia responses on the same day. Methods: Eighteen young men (age 26 ± 2 years; height 174.2 ± 6.0 cm; body mass 70.2 ± 8.1 kg; body fat 18.0 ± 3.8 %; mean ± standard deviation) participated in this study. Oral temperature, heart rate variability (HRV) from 5-min of electrocardiogram data, and diving bradycardia responses were measured at 0900, 1300, and 1700 hours daily. All participants performed diving reflex tests twice in the sitting position with the face immersed in cold water (1.9–3.1 °C) and apnea at midinspiration for a minimum of 30 s and as long as possible, in consecutive order. Results: Oral temperature was found to be less in the morning (0900) than in the afternoon (1300) and evening (1700). In the frequency domain parameters of heart rate variability, the natural logarithms of high-frequency power were higher in the morning than in the evening. All participants showed bradycardia response to the two diving reflex tests. The peak values of R–R interval during the diving reflex test both for as long as possible and 30 s were longer in the morning than in the afternoon and evening. Conclusion: Our results indicated that the maximal bradycardia during the diving reflex test exhibits a diurnal variation, with peak levels at morning and gradual decrease towards the evening. The HRV indexes show the same variation.
KW - Autonomic nervous system
KW - Bradycardia
KW - Circadian rhythm
KW - Vagal activity
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U2 - 10.1007/s10286-016-0342-1
DO - 10.1007/s10286-016-0342-1
M3 - Article
C2 - 26795189
AN - SCOPUS:84955245513
SN - 0959-9851
VL - 26
SP - 135
EP - 140
JO - Clinical Autonomic Research
JF - Clinical Autonomic Research
IS - 2
ER -