Living high-training low (LHTL), living at high altitude and training at sea level,
is reported to be beneficial in enhancing physical performance. Effect of LHTL on
cardiac function which is one of major determinants in performance, however, was not
examined. To address this issue, 21 well-trained triathletes divided into control
(n = 10, living and training at sea level) and LHTL group (living at 1980 m altitude
≥ 12 hrs/day and training at sea level) were Doppler echocardiographically examined
before and at the end of the two-week program. Heart rate and blood pressure did not
change in both groups. At end of the training, left ventricular endsystolic diameter
of LHTL group was smaller than that of controls (32 vs 34 mm, P < 0.05). Shortening
fraction and ejection fraction in LHTL group increased by 9 % and 17 %, respectively,
P < 0.05. Preejection period/ejection time was more greatly reduced in LHTL group
(P < 0.05). Stroke volume and cardiac output in LHTL increased. Diastolic function
was not significantly affected by LHTL. These results suggest that LHTL produced an
improvement of systolic function underlined by incremented left ventricular contractility,
which might be associated with increased ?-adrenergic receptor or an improved myocardial
energy utilization.
Key words
High altitude - hypoxia - exercise - Doppler echocardiography - systolic function
