2007, Piran, Slovenia
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2007, Piran, Slovenia

2007, Piran, Slovenia 2007, Piran, Slovenia

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Environmental Ergonomics XII Igor B. Mekjavic, Stelios N. Kounalakis & Nigel A.S. Taylor (Eds.), © BIOMED, Ljubljana 2007 Borg, G., 1970. Perceived exertion as an indicator of somatic stress. Scand J Rehab Med 2-3, 92-98. Moore, L. G., Harrison, G. L., McCullough, R. E., Micco, J., Tucker, A., Weil, J. V. and Reeves, J. T., 1986. Low acute hypoxic ventilatory response and hypoxic depression in acute altitude sickness. J App. Physiol 60, 1407-1412. Murdoch, D. R., 1995a. Symptoms of infection and altitude illness among hikers in the mount everest region of nepal. Av. Sp. Env. Med. 66, 148-151. Murdoch, D. R., 1995b. Altitude illness among tourists flying to 3740 meters elevation in the Nepal Himalayas. J. Trav. Med. 2, 255-256. Roach, R. C., Maes, D., Sandoval, D., Robergs, R. A., Icenogle, M., Hinghoffer- Szalkay, H., Lium, D. and Loeppky, J. A., 2000. Exercise exacerbates acute mountain sickness at simulated high altitude. J. App Physiol 88, 581-585. Thake, C. D. and Price, M. J., 2006. Repeatability of pulse oximetry in hypoxic and normoxic incremental exercise. J Sports Sci 23, 1227-1228. 100

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). 101

Environmental Ergonomics XII<br />

Igor B. Mekjavic, Stelios N. Kounalakis & Nigel A.S. Taylor (Eds.), © BIOMED, Ljubljana <strong>2007</strong><br />

Borg, G., 1970. Perceived exertion as an indicator of somatic stress. Scand J Rehab<br />

Med 2-3, 92-98.<br />

Moore, L. G., Harrison, G. L., McCullough, R. E., Micco, J., Tucker, A., Weil, J. V.<br />

and Reeves, J. T., 1986. Low acute hypoxic ventilatory response and hypoxic<br />

depression in acute altitude sickness. J App. Physiol 60, 1407-1412.<br />

Murdoch, D. R., 1995a. Symptoms of infection and altitude illness among hikers in<br />

the mount everest region of nepal. Av. Sp. Env. Med. 66, 148-151.<br />

Murdoch, D. R., 1995b. Altitude illness among tourists flying to 3740 meters<br />

elevation in the Nepal Himalayas. J. Trav. Med. 2, 255-256.<br />

Roach, R. C., Maes, D., Sandoval, D., Robergs, R. A., Icenogle, M., Hinghoffer-<br />

Szalkay, H., Lium, D. and Loeppky, J. A., 2000. Exercise exacerbates acute<br />

mountain sickness at simulated high altitude. J. App Physiol 88, 581-585.<br />

Thake, C. D. and Price, M. J., 2006. Repeatability of pulse oximetry in hypoxic and<br />

normoxic incremental exercise. J Sports Sci 23, 1227-1228.<br />

100

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