Elite endurance athletes regularly attend multiple altitude training camps at venues such as Iten, Kenya (2,300m) and Font Romeu, France (1,800m) during the season. The primary aim of traditional live-high, train-high (LHTH) altitude training is to enhance oxygen carrying capacity, through an increase in heamoglobin mass and ultimately improve competitive endurance performance. The optimal ‘hypoxic dose’ for a LHTH altitude training camp has been established in various research studies over the last 20 years, however it appears that the dose is not optimal for all endurance athletes. Individual differences in physiological and haematological response to altitude mean that not all athletes benefit from the same ‘hypoxic dose’. The PhD thesis utilised short-term simulated hypoxic exposures to understand how individuals responded to hypoxia and introduced a pre-screening tool to optimise the current altitude training strategies of elite endurance athletes. The experimental studies found that hypoxic sensitivity (changes in EPO response, changes in hypoxic ventilatory response and changes in arterial oxygen saturation) played a role in predicting which athletes would increase heamoglobin mass and improve maximal oxygen uptake, after a four week LHTH altitude training camp at 2,300m. As a result, a hypoxic sensitivity test could be used by athletes and coaches to individualise the ‘hypoxic dose’ of a training camp and also individualise the training that takes place during a camp.