Delayed Acclimatization of the Ventilatory Threshold in Healthy Trekkers

Objective To test the hypothesis that acclimatization to high altitude results in an improvement of the ventilatory threshold (VT). Methods Eight lowlanders underwent cardiopulmonary exercise testing with a cycle ergometer to determine VT and peak oxygen uptake (Vo2peak) in Coventry, United Kingdom (altitude: 80 m), on arrival in Leh, India (altitude: 3500 m), and after 12 days of acclimatization that included a 5-day high altitude trek up to 4770 m. Results Vo2peak fell on arrival at 3500 m and remained depressed at 12 days. VT was depressed on arrival at high altitude and was further depressed at 12 days. VT as a proportion of the Vo2peak was decreased on arrival at high altitude, and after acclimatization, this relationship was further decreased. Conclusions Individuals who are sedentary or not participating in regular physical training appear to require a longer period of acclimatization than trained athletes. With the increasing numbers participating in high-altitude trekking and charity climbs of peaks, such as Mt. Kilimanjaro, this information has clinically significant practical implications for those leading or acting as medical advisors.