Yang F;  Air Force Health Care Center for Special Services, Hangzhou, China.
Tan W; Tian Y; Wu Q; Feng X; Hu G; Li O

Physiological Reports. 14(8):e70864, 2026 Apr.
Headings added by Dr Older

AIM
To evaluate altitude-stratified differences in static lung function,
aerobic capacity, and exercise physiology under standardized normoxic
conditions, and identify multiple predictors of peak oxygen uptake (VO2)
reduction among asymptomatic men after prolonged residence at varying
altitudes.
METHODS
We conducted a cross-sectional study of 103 asymptomatic men
stratified by residential altitude: low (<2500 m; n = 35), high (2500-3500
m; n = 32), and very high (>3500 m; n = 36). All underwent spirometry,
fasting blood tests, and symptom-limited cardiopulmonary exercise testing
(CPET) in normoxia.
RESULTS
Multiple linear regression identified independent
predictors of peak VO2/kg. Very high-altitude residents had significantly
lower peak VO2/kg (-13.4 mL.min-1.kg-1 vs. low altitude, p < 0.001),
reduced oxygen pulse, and impaired small-airway function (MMEF, FEF75; p <
0.05), despite preserved ventilatory efficiency (VE/VCO2 slope, p =
0.782). Hemoglobin was elevated at higher altitudes; triglycerides were
higher only above 3500 m. Age (beta = -0.285), regular exercise (>=3
sessions/week; beta = +3.648), and very high-altitude residence (beta =
-13.370) independently predicted peak VO2/kg (all p < 0.001; R2 = 0.739).
CONCLUSIONS
Residence above 3500 m causes persistent cardiopulmonary impairment driven
by circulatory limitations and smoking, despite preserved ventilatory
efficiency. Normoxic assessment identifies regular exercise (>=3
sessions/week) as a key countermeasure against altitude-induced
deconditioning. Prioritizing smoking cessation and mandatory exercise
programs is therefore recommended for long-term health in high-altitude
personnel.