Diving bradycardia of elderly Korean women divers, haenyeo, in cold seawater: a field report

The purpose of the present field study was to explore diving patterns and heart rate of elderly Korean women divers (haenyeo) while breath-hold diving in cold seawater. We hypothesized that the decreasing rate in heart rate of elderly haenyeos during breath-hold diving was greater and total diving time was shorter than those of young haenyeos from previous studies. Nine haenyeos participated in a field study [68 +/- 10 yr in age, ranged from 56 to 83 yr] at a seawater temperature of 10 to 13 degrees C. Average total diving time including surface swimming time between dives was 253 +/- 73 min (155-341 min). Total frequency of dives was 97 +/- 28 times and they dived 23 +/- 8 times per hour. All haenyeos showed diving bradycardia with a decreased rate of 20 +/- 8% at the bottom time (101 +/- 20 bpm) when compared to surface swimming time (125 +/- 16 bpm) in the sea. Older haenyeos among the nine elderly haenyeos had shorter diving time, less diving frequencies, and lower heart rate at work (p<0.05). These reductions imply that haenyeos voluntarily adjust their workload along with advancing age and diminished cardiovascular functions.