Leucocyte and erythrocyte counts during a multi-stage cycling race ('the Milk Race').

Abstract

Venous blood samples were taken from eight competitors in mid-evening after a racing day, and in the early morning before the next day's race, three times during the course of the Milk Race, 1992. These were used to gather information about the changes in circulating leucocyte levels in response to the exceptionally high sustained daily workload required during a major multi-stage race. The primary objective was to provide knowledge of 'normal' values against which future clinical judgements of abnormality might be made in these unusual circumstances. During the race, estimated energy output was about 25 MJ (6000 kCal)/day. The mean total circulating leucocyte numbers (per litre of blood), and those of individual leucocyte classes (neutrophil, lymphocyte, monocyte, eosinophil and basophil) were all inside the normal range both in the morning and in the evening. Evening counts were, however, 30-50% higher than morning counts, for all classes except eosinophils. We conclude that individual clinical decisions about leucocyte levels can best be made using normal (sedentary man) values if a morning sample is taken.Keywords: heavy exercise, leucocytosis, cycling, circadian This brief study was initiated after reading a newspaper report that a competitor in the 1991 Tour de France had been advised to retire from competition because 'Doctors had found a high white cell count' and suspected a viral infection. No more information than this was given, but it raised the question in our minds 'What is high in the context of the Tour de France?' What standards of normality were applied? Exercise is well-known to induce a substantial leucocytosis, and this may be both transient and delayed, the latter being relatively persistent, even when induced by a limited period of severe exercise'. We decided that it would be useful to seek normal values in the unusual context of a major cycle stage race, by sampling in the two periods when it seems most probable that a competitor might present himself to a doctor with complaints of feeling unwell; namely at the end of a day (in the mid-evening), or early in the morning, soon after waking.A delayed leucocytosis (at 3h into recovery) has been reported in response to single bouts of exercise2, or even to double bouts of exercise in the laboratory3 that is typically a pure neutrophilia, although following 3 h of exhaustive exercise, monocytosis and eosinopaenia were noted in recovery4. It has been hypothesized that the delayed peak in neutrophil leucocytes is induced by the earlier elevation in cortisol level caused by the exercise. It is well-known that cycle stage races involve massive workloads, which have been assessed to amount to a mean energy expenditure of about 25 MJ and a maximum of about 32.5 MJ/day (6000 and 7800 kCal/day respectively) during the Tour de France5. It is also known that cortisol turnover is normally related to energy turnover during exercise6. Such high levels of work are therefore bound to involve relatively high cortisol outputs, which might be expected to exert...

Basophils and exercise-induced hypoxemia in extreme athletes

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Ramadan Fasting and Weight-Lifting Training on Vascular Volumes and Hematological Profiles in Young Male Weight-Lifters

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