european college of sport science

Saturday, June 27th, 2009
after A4. Mean Hb increased from 135 to 140 g/L across A1-3 and then to 142 g/L after A4. Both parameters had returned to baseline
after 10 min. Nadir SaO2 after apnea was 94% for A1-3 and 81% for Amax.
Conclusions: We conclude that elite divers, with an extended apneic ability compared to non-divers, achieve further spleen contraction
and red cell release during maximal effort apneas compared to medium effort apneas. This appears related to the lower SaO2. This
information may be important when comparing responses between groups with different apneic ability, and for elite apneists when
planning their warm-up.
References
Richardson M., Lodin A., Reimers J., Schagatay E. (2008). Short-term effects of normobaric hypoxia on the human spleen. Eur J Appl
Physiol 104, 395-399.
Schagatay E., Andersson J.P.A., Hallén M., and Pålsson B. (2001). Selected contribution; Role of spleen emptying in prolonging apneas in
humans. J Appl Physiol, 90, 1623-1629.
CHANGES IN PACING STRATEGY IN RESPONSE TO AN ACUTE SHIFT TO AND FROM HYPOXIA
LINDSAY, T., ANSLEY, L., NEARY, J.P., HUNTER, A., ST CLAIR GIBSON, A., SKOWNO, J., NOAKES, T.D.
1. UNIV. CAPE TOWN, SOUTH AFRICA, 2. NORTHUMBRIA UNIV., NEWCASTLE, UK, 3. UNIV. REGINA, CANADA, 4. UNIV. STIRLING, UK, 5. RED
CROSS WAR MEMORIAL CHILDREN'S HOSPITAL, CAPE TOWN, SOUTH AFRICA
Introduction: It is well known that hypoxia decreases exercise capacity but less is known about how acute changes in ambient oxygen
concentration (FIO2) affect pacing profiles. The pacing profile during a time trial usually includes an initial surge, a middle plateau and an
end-spurt (Amann et al. 2006; Noakes et al., 2008; Billat et al., 2006). The purpose of this study was to describe changes in pacing profile
and physiology in response to a mid-exercise change in FIO2.
Methods: Eight male cyclists completed two 20 km time trials in random order. In one trial, the 1st 10 km was normoxic (FIO2=21%) and
the 2nd 10 km was hypoxic (FIO2=15% ~2700 m). The order was reversed in trial two. Subjects were blinded to the conditions. The trials
were done inside a chamber set at normobaric pressure. Subjects acclimatised to the initial FIO2 for 10 min before each trial. Expired
gases (4, 14 km), cardiac output (Q) (continuous), and blood gases (0, 4, 9, 14, 19 km) were measured. Subjects used their own bicycles on
an electrically braked cycle trainer. PO was averaged over 2 km. Analysis was by a Students’ t-test and repeated-measures ANOVA with
Bonferroni post-hoc.
Results: Power output (PO) was lower in hypoxia at every interval except 12 and 14 km (p