The athlete biological passport for the fight against doping is currently based on longitudinal monitoring for abnormal changes in cellular blood parameters. Serum parameters related to altered erythropoiesis could be considered for inclusion in the passport. The aim of this study was to quantify the changes in such parameters in athletes during a period of intense exercise. 12 highly trained cyclists tapered for 3 days before 6 days of simulated intense stage racing. Morning and afternoon blood samples were taken on most days and analysed for total protein, albumin, soluble transferrin receptor and ferritin concentrations. Plasma volume was determined via total haemoglobin mass measured by carbon-monoxide rebreathing. Percent changes in means from baseline and percent standard errors of measurement (analytical error plus intra-athlete variation) on each measurement occasion were estimated with mixed linear modelling of log-transformed measures. Means of all variables changed substantially in the days following the onset of racing, ranging from ?13% (haemoglobin concentration) to +27% (ferritin). After the second day, errors of measurement were generally twice those at baseline. Plasma variables were affected by heavy exercise, either because of changes in plasma volume (total protein, albumin, haemoglobin), acute phase/inflammatory reactions (ferritin) or both (soluble transferrin receptor). These effects need to be taken into consideration when integrating a plasma parameter into the biological passport model for athletes.

The observed changes are in line with normal diurnal variations. There is no indication that travel will affect haematological variables in way that might be mistaken for blood doping.

In the fight against doping in sports, indirect detection methods using Hb and Hct are starting to play a more and more important role. The goal of this investigation was to quantify the changes in PV during a 2 week study of endurance exercise simulating a cycling stage race and to test for PV changes relative to the circadian rhythm of the athlete. 15 endurance trained triathletes and cyclists performed a standardised 3 day taper (no exercise), followed by a 9 day cycling stage race simulation. Hb showed a mean increase of 4% during the 3 day taper period which was caused by a reduction in PV. During the exercise phase Hb dropped by 1.5 g/dl or 11%, which relates to an average expansion of PV by 0.6 l or 16%. The fluctuations in morning PV showed a wide inter-subject variability. The smallest change was 493 ml (10%), which was accompanied with a drop in Hb from 14.8 g/dl to 13.7 g/dl. The largest increase was 1277 ml (or 25%). The corresponding Hb values for this subject dropped from 15.8 g/dl to 13.1 g/dl (figure 2). The Hb concentration of the morning and evening samples showed a mean difference of approximately 0.6 g/dl or 3.7%, which was observed both during the taper (without exercise) and stage race phases. This study showed that exercise induced changes of PV in healthy trained endurance athletes can be up to 1277 ml or 25% when tested at the same time of the day. This fact needs to be considered in the interpretation of blood profiles as this value might even be higher if the test was to be performed at different times of the day. In our study we were able to demonstrate that the circadian rhythm of Hb concentration remains stable even under maximal PV expansion and reaction to exercise. This finding could be implemented in the athlete biological passport model to help reduce the variation of biological markers.

WADA's biological passport uses Hb and Ret% as markers for detection of blood doping. Athletes often have to travel long distances when they go for competition or training camps. Thus it is a legitimate discussion if the influence of travelling has a significant impact on these markers. For that reason the aim of this study was to investigate Hb and Ret% before and after a day of travelling including a flight of 8 h. 15 male endurance athletes performed a 14 h journey including an 8 h flight. Hydration status, bodyweight and fluid intake was controlled. Blood was sampled in the morning and evening of day 1 and day 2 for interday comparisons and to control if intraday fluctuations are a result of travelling or circadian rhythm. Day 1 The subject`s bodyweight did not show a significant difference between the two timepoints of day 11, with 72.9±5.9 kg in the morning and 72.5±5.8 kg in the evening. The subjects showed a positive fluid balance of 982±780 ml. Hb showed a significant decrease from 14.5±0.6 g/dl to 14.0±0.6 g/dl while Ret% remained unchanged (1.09±0.25% vs 1.03±0.29%). Day 2 The bodyweight of the subjects was 71.9±5.8 kg in the morning and 72.9±5.7 kg in the evening. The fluid balance was 407±908 ml. The high SD is a sign that some of the subjects had a negative fluid balance, which was the case for four subjects. Hb showed a significant decrease from 14.9±0.6 g/dl to 14.2±0.5 g/dl while Ret% remained unchanged (1.03±0.30% vs 1.06±0.32%). The homeostasis of the human body regarding its fluid balance and hydration remains stable during changing environmental conditions which occur at a typical travel day including an 8 h flight. We conclude that an 8 h flight does not change the haematological variables used in the biological passport in a bigger range than by circadian fluctuations. Thus blood samples after flights up to 8 h can be used for the interpretation in antidoping.

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