2007, Piran, Slovenia

Altitude Physiology
EFFECTS OF INTERMITTENT HYPOXIA ON SaO2, CEREBRAL
AND MUSCLE OXYGENATION DURING MAXIMAL EXERCISE
Helen C Marshall 1 , Michael J Hamlin 1 , John Hellemans 2 , Carissa Murrell 3 , Nik
Beattie 3 , Ien Hellemans 4 , Tracey Perry 4 , Aimee Burns 4 & Philip N. Ainslie 3
1 Lincoln University, Christchurch, New Zealand
2 New Zealand Academy of Sport, Dunedin, New Zealand
3 Department of Physiology, Otago University, Dunedin, New Zealand
4 Department of Nutrition, Otago University, Dunedin, New Zealand
Contact person: hamlinm@lincoln.ac.nz
INTRODUCTION
Exposure to intermittent hypoxia (IHE) elevates ventilatory sensitivity to hypoxia and
evokes subsequent hypocapnia (Ainslie et al., 2007); however, studies have reported
no concurrent gas exchange alterations during maximal exercise (Foster et al., 2006).
Athletes who experience significant exercise-induced hypoxemia (EIH), however,
may display different physiological responses following IHE during exercise than
those who do not show EIH. Reductions in the saturation of arterial oxygen (SaO2)
greater than 4% during incremental exercise have been classified as a threat to
systemic oxygen transport and subsequently V & O2max (Dempsey & Wagner, 1999). In
support of this notion, it has recently been shown that there is a greater muscle
deoxygenation, as determined by near-infrared spectroscopy (NIRS), at maximal
exercise in individuals with EIH (Legrand et al., 2005). It is not known how exposure
to intermittent hypoxia may affect the degree of EIH or cerebral (central) or muscle
(peripheral) oxygenation during maximal exercise. The aims of this investigation,
therefore, were to determine the effects of IHE on SaO2 and NIRS-assessed
oxygenation in the muscle and brain during incremental exercise, in athletes with a
known EIH.
METHODS
Eight (6 males, 2 females) highly trained competitive athletes (5 cyclists, 3
triathletes), who had previously demonstrated EIH volunteered to participate in this
study. Participants’ characteristics are presented in Table 1. This study was approved
by the University of Otago’s Human Ethics Committee and conformed to the
standards set by the Declaration of Helsinki.
Table 1. Characteristics of the participants in the placebo and intermittent hypoxic
exposure (IHE) groups.
Placebo Group IHE Group
Age (yr) 33.0 (10.6) 27.5 (9.2)
Gender 2 males, 2 females 4 males
Height (m) 1.7 (0.1) 1.8 (0.0)
Body mass (kg) 72.1 (17.1) 78.8 (7.9)
V & O2peak (mL.kg -1 .min -1 ) 65.9 (1.6) 68.1 (6.1)
Training load (h.wk -1 ) 12.1 (7.5) 14.9 (7.4)
Values are mean (SD).
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