In contrast to the aforementioned, a study by van Hall et al. (128), published in 2001, suggested that the lactated paradox was simply a time – dependent phenomenon, being present during the early week of acclimatization and disappearing thereafter. Two years later, Pronk et al. (98) challenged this condlusion. They measured the lactate response to the same absolute work load on ascent to altitude and at two, four, six and eight weeks to track changes in the response over time at altitude. They observed the expected increase in the blood lactate response to exercise upon ascent to altitude and the now –classic decrease in the blood lactate response with continued exposure to altitude. They also confirmed the link of the lactate response to changes in plasma catecholamines. They concluded that there was no evidence of a reversal of the lactate paradox with continued altitude exposure. Lundby and van Hall’s response (75) to this study, and Pronk’s counter response (97), make interesting reading, but indicate how much the two are apart.