초록 열기/닫기 버튼
This study examined whether repeated breath-hold diving (BHD) in cold water would impact on heart rate (HR), blood lactate concentration (Lac), and oxygen saturation (SpO2) responses. Seven young healthy collegiate men (20.4 ± 0.5 yrs, 176.4 ± 5.2 cm, 68.6 ± 5.1 kg, 22.0 ± 1.3 kg·m-2) who were open water diver certified participated in two testing sessions; a cold water diving (CW; 17 ± 1oC) and a moderate water diving (MW; 27 ± 1oC). They were not acclimated to cold prior to study and familiarized with BHD. In both sessions, they repeated a 30-sec long, 5-meter deep BHD for 20 times, and rested 30 sec between each trial, except 1 min resting at 5th, 10th, 15th, and 20th trials when measurements were taken. Baseline data for HR, Lac, and SpO2 outside of the pool were obtained at rest. During BHD, HR was measured at both bottom and surface using electronic HR monitor by a skilled scuba diver. HR, Lac using a finger prick method, and SpO2 using pulse oximetry were measured after 5th, 10th, 15th, and 20th trials. All completed BHD sessions in both water temperature. During BHD, HR increased as the diving was repeated and the final HR was 129.7 ± 17.3 for MW and 134.1 ± 15.1 beat·min-1 for CW. No water temperature effects were found in HR. Lac changed from 1.4 ± 0.3 at rest to 4.5 ± 1.5 at the final in MW and from 1.4 ± 0.2 at rest to 5.4 ± 1.2mmol/L at the final in CW, and the water temperature effect was noticed (p < 0.05). As BHD progressed, SpO2decreased gradually from 98.4 ± 0.5 at rest to 71.3 ± 4.3% after 20th trial in MW and from 98.6 ± 0.5 at rest to 65.6 ± 3.5% at the end of CW, and a significant interaction was noticed (p < 0.05). Data indicated that a repeated BHD at cold water resulted in an increased blood lactate and decreased blood oxygen saturation compared to relatively comfortable water temperature in an unhabituated human. No cardiac alterations were obvious during BHD in cold water.
