A cross-sectional study of differences in 6-min walk distance in healthy adults residing at high altitude versus sea level.
BACKGROUND
We sought to determine if adult residents living at high altitude have developed sufficient adaptation to a hypoxic environment to match the functional capacity of a similar population at sea level. To test this hypothesis, we compared the 6-min walk test distance (6MWD) in 334 residents living at sea level vs. at high altitude.


METHODS
We enrolled 168 healthy adults aged ≥35 years residing at sea level in Lima and 166 individuals residing at 3,825 m above sea level in Puno, Peru. Participants completed a 6-min walk test, answered a sociodemographics and clinical questionnaire, underwent spirometry, and a blood test.


RESULTS
Average age was 54.0 vs. 53.8 years, 48% vs. 43% were male, average height was 155 vs. 158 cm, average blood oxygen saturation was 98% vs. 90%, and average resting heart rate was 67 vs. 72 beats/min in Lima vs. Puno. In multivariable regression, participants in Puno walked 47.6 m less (95% CI -81.7 to -13.6 m; p < 0.01) than those in Lima. Other variables besides age and height that were associated with 6MWD include change in heart rate (4.0 m per beats/min increase above resting heart rate; p < 0.001) and percent body fat (-1.4 m per % increase; p = 0.02).


CONCLUSIONS
The 6-min walk test predicted a lowered functional capacity among Andean high altitude vs. sea level natives at their altitude of residence, which could be explained by an incomplete adaptation or a protective mechanism favoring neuro- and cardioprotection over psychomotor activity.
Deirdre
D
Caffrey
J Jaime
JJ
Miranda
Robert H
RH
Gilman
Victor G
VG
Davila-Roman
Lilia
L
Cabrera
Russell
R
Dowling
Talia
T
Stewart
Antonio
A
Bernabe-Ortiz
Robert
R
Wise
Fabiola
F
Leon-Velarde
Division of Pulmonary and Critical Care, School of Medicine, Johns Hopkins University, 1800 Orleans St, Suite 9121, Baltimore, MD 21205, USA. wcheckl1@jhmi.edu.
William
W
Checkley