急性暴露於中海拔高地對於划船選手心跳率變異性的影響

Effects of Acute Exposure to Moderate Altitude on Heart Rate Variability in Rowers

目的：本研究的目的在探討急性暴露於中海拔高地環境，對於優秀西式划船選手心跳率變異性的影響。方法：11位優秀西式划船選手自願參與本實驗，作為實驗組（年齡，20.7±2.0歲；身高，177.5±3.5公分；體重，77.0±6.9公斤），另以11位坐姿生活的大專生作為控制組（年齡，21.0±1.1歲；身高，174.3±7.5公分；體重，68.8±15.1公斤）。在暴露於2,200~2,600公尺高地7天的前、中與後，實驗組必須分別接受坐姿安靜心跳率以及在室內划船測功儀上，利用隨機平衡次序的方式進行兩種非最大運動強度的測驗（30%與60%V.O2max）。控制組僅在海平面上進行安靜心跳率的測量。在所有的測試中，均持續測量心跳率變異性（heart rate variability，HRV）。透過R-R間隔的功率頻譜分析，可獲得極低頻（VLF功率：0.00-0.04Hz）、低頻（LF功率：0.04-0.15Hz）與高頻（HF功率：0.15-0.4Hz）部份，進而評估自主神經系統的功能。結果：在海平面時，實驗組的安靜心跳率、VLF功率、總功率與LF／HF比值均顯著地低於控制組，但是LF功率則顯著高於控制組。雖然實驗組在高地時的安靜心跳率以及兩種不同強度的運動心跳率，均明顯地高於海平面時，但是HRV各變項在不同海拔高度之間，並無顯著差異，除了第一天暴露於高地時，30%V.O2max的運動中LF功率顯著地低於海平面之外。結論：雖然優秀划船選手急性暴露於中海拔高地環境時，會顯著地增加安靜心跳率、輕度與中度運動時的心跳率，但是並不會影響自主神經的活動情形。上升的心跳率可能源自於其他的生理回饋機制。

PURPOSE: The present study was to investigate the effects of acute exposure to moderate altitude on heart rate variability in elite rowers. METHODS: Eleven elite male rowers voluntary to participate in this study as a treatment group (age, 20.7±2.0 yrs; height, 177.5±3.5 cm; weight, 77.0±6.9 kg), and another eleven sedentary male college students as a control group (age, 21.0±1.1 yrs; height, 174.3±7.5 cm; weight, 68.8±15.1 kg). Treatment group completed one resting measurement in the upright sitting position and two submaximal steady-state exercises (30% and 60%V.O2max) in random balanced order on rowing ergometer before, during and after 7 days of a sojourn at 2,200-2,600 m above sea level. Control group only completed one resting measurement at sea level. Beat-to-beat heart rate variability (HRV) was measured continuously during the tests. Autonomic function was assessed by very low frequency (VLF power: 0.00-0.04 Hz), low frequency (LF power: 0.04-0.15 Hz) and high frequency (HF power: 0.15-0.4 Hz) obtained from the power spectra analysis of R-R interval. RESULTS: At sea level, the resting heart rate, VLF power, total power and LF/HF ratio in treatment group were significantly lower than control group, however, the LF power was significantly greater than control group. Although the resting heart rate and two exercising heart rates in treatment group were observably greater at moderate altitude than at sea level, there were no significant differences on the variables of HRV between different altitudes, except that the LF power of 30%V.O2max exercise in day 1 at moderate altitude was significantly lower than before exposing to altitude. CONCLUSION: Although elite rowers exposure to moderate altitude would significantly increase resting heart rate, mild and moderate exercising heart rate, there were no effects on the autonomic activity. The increased heart rate might be contributed by the other physiological feedback mechanisms.