Altitude training and individual hemoglobin mass response in athletes

Altitude training is frequently used by elite athletes to obtain potential benefits in sea-level performance. One of the main recognized physiological adaptations leading to enhanced sea- level performance is a hypoxia-induced increase in hemoglobin mass (Hbmass). During the last decades, several types of altitude training have been developed, which can be performed under either hypobaric hypoxia (HH, natural altitude) or normobaric hypoxia (NH, simulated altitude). Whether NH and HH can be used interchangeably for altitude training is still unclear. Moreover, especially from an athlete’s perspective, the individual adaptations to and the interchangeability of NH and HH are of interest. Therefore, to compare individual and mean Hbmass responses during an 18-day live hightrain low (LHTL) altitude training camp in either NH or HH, we designed a randomized matched controlled (n = 28) study and a crossover (n = 15) study with endurance athletes. To more precisely quantify the individual Hbmass response to altitude training, we implemented error- reducing duplicate Hbmass measures. Furthermore, since altitude training is primarily used by elite endurance athletes that typically present elevated Hbmass values, we tested the hypothesis that athletes with a high initial Hbmass starting an altitude sojourn will have a limited ability to further increase their post-altitude Hbmass in male endurance and team-sport athletes (n = 58). The present thesis indicates that hypobaric and normobaric LHTL camps evoke a similar mean increase in Hbmass as well as similar performance changes following an 18-day LHTL camp, suggesting that both hypoxic conditions can be used equally for an LHTL training camp. Among the mean Hbmass changes, there was a notable inter-individual variation that could not be explained by the variation in the initial Hbmass. This emphasizes the importance of individual Hbmass response evaluation for altitude training in athletes. -- L’entrainement en altitude est couramment utilise par les sportifs d’elites afin d’obtenir des benefices ameliorant la performance au niveau de la mer. Le mecanisme-clef reside dans l’augmentation de la masse totale en hemoglobine (Hbmass) induite par l’hypoxie. Ces dernieres decennies, plusieurs methodes d’entrainement en altitude ont ete developpees, soit en hypoxie hypobare (HH, altitude reelle) soit en hypoxie normobare (NH, altitude simulee). La question de savoir si HH et NH sont interchangeables n’est pas encore completement resolue. En particulier, les effets de NH vs. HH sur les reponses individuelles de Hbmass sont encore mal connus. Par consequent, afin de comparer les reponses de Hbmass au cours d’un stage de 18 jours "vivre en haut et s’entrainer en bas, LHTL" soit en NH ou en HH, nous avons realise un protocole randomise controle (n = 28) puis un protocole croise (n = 15) avec des athletes d’endurance. Afin de quantifier plus precisement les reponses individuelles de Hbmass et de reduire les erreurs, les mesures ont ete dupliquees. De plus, comme l’entrainement en altitude est utilise a ce jour principalement par les athletes d’endurance ayant un niveau initial eleve de Hbmass, nous avons teste l’hypothese que les athletes ayant une haute valeur de Hbmass ont une augmentation limitee de celle-ci suite a un stage en altitude, que ce soit avec des sportifs d’endurance ou de sport collectif (n = 58). Le travail de doctorat realise montre que LHTL induit la meme augmentation de Hbmass en hypoxie normobare et hypobare, ainsi qu’une amelioration similaire de la performance aerobie. Aussi, les deux conditions hypoxiques (HH et NH) peuvent etre utilisees pour des stages de type LHTL. De plus, une variabilite importante interindividuelle des reponses de Hbmass a ete rapportee, qui ne dependent pas du niveau initial de Hbmass des sujets. Ceci met en evidence la necessite de mesurer ces reponses individuelles avec precision.