Peak blood lactate and blood lactate vs. workload during
acclimatization to 5,050 m and in the deacclimatization.
Grassi, Bruno, Mauro Marzorati, Bengt Kayser, Marco Bordini, Angelo
Colombini, Marco Conti, Claudio Marconi, and Paolo Cerretelli.
Section of Physiology, Istituto di Tecnologie Biomediche Avanzate,
Consiglio Nazionale delle Ricerche, 20131 Milano, Italy;
D[acute]epartement de Physiologie, Centre M[acute]edical
Universitaire, 1211 Gen[grave]eve 4, Switzerland
APStracts 2:0424A, 1995.
Peak blood lactate ([Lab]p) and the blood lactate ([Lab]) vs. work
load (w) relationship during acclimatization to altitude and in the
deacclimatization were evaluated on 10 Caucasian lowlanders, at sea
level (SL0), after 1 (ALT1wk), 3 (ALT3wk) and 5 (ALT5wk) weeks at
5,050 m, and weekly during the first 5 weeks after return to sea
level (SL1wk to SL5wk). Incremental bicycle ergometer exercises (30 W
added every 4 min up to exhaustion) were performed. At ALT1wk and at
ALT5wk the experiments were repeated in hypobaric normoxia (ALT1wk-O2
and ALT5wk-O2). [Lab] was determined at rest and during the last 30 s
of each w. [Lab]p was taken as the highest [Lab] during recovery.
Acid-base status (pH and [HCO3-] in arterialized capillary blood) was
determined at rest. [Lab]p (in mM) was 11.5+/-2.2 (x+/-SD) (SL0),
8.0+/-3.0 (ALT1wk), 6.4+/-1.4 (ALT3wk), 6.3+/-0.9 (ALT5wk), 8.0+/-1.9
(SL1wk), 9.4+/-1.7 (SL2wk), 10.8+/-1.4 (SL3wk), 11.3+/-2.6 (SL4wk),
11.6+/-2.2 (SL5wk). At ALT1wk-O2 and ALT5wk-O2 peak w (wp) increased,
compared to ALT1wk and ALT5wk, whereas no changes were observed for
[Lab]p. [Lab] vs. w was shifted to the left (i.e. higher [Lab] were
found for the same w) at ALT1wk compared to SL0, and partially
shifted back to the right (i.e. lower [Lab] were found for the same
w) at ALT3wk and ALT5wk. At ALT1wk-O2 and ALT5wk-O2 [Lab] vs. w were
superimposed on that at SL0. At SL1wk to SL5wk [Lab] vs. w were
shifted to the right compared to that at SL0. At ALT1wk a condition
of respiratory alkalosis was found, which was only partially
compensated during acclimatization. At SL1wk the acid-base status was
back to normal. It is concluded that: 1) The reduced [Lab]p at
altitude is still present for 2-3 weeks after return from altitude;
is not attributable to reduced wp nor to hypoxia per se, nor to a
reduced buffer capacity; alternatively, it could be related to some
"central" determinants of fatigue (see "Discussion").
2) The [Lab] vs. w leftward shift at altitude was due to hypoxia per
se. 3) The factor(s) responsible for the [Lab] vs. w partial
rightward shift during acclimatization could still be effective
during the first weeks after return to sea level.
Received 28 February 1995; accepted in final form 3 October 1995.
APS Manuscript Number A229-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 6 November 95