Variability of Serum Markers of Erythropoiesis during 6 Days of Racing in Highly Trained Cyclists

Abstract

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 effect of a period of intense exercise on the marker approach to detect growth hormone doping in sports

“…After the initial resting phase (days 1–3), the race period starts (days 4–12). Days 6–8 of this period show the lowest GH‐scores, which correlates to the observed plasma volumes which showed the highest values on these days …”

“…Haemoglobin mass was measured in each subject in duplicate at the beginning of the study. The true haemoglobin mass for each time point was calculated taking into account the exact loss of haemoglobin due to blood sampling …”

Effects of hydration status during heat acclimation on plasma volume and performance

“…Similar to our findings, in a crossover design Keiser et al also implemented variable training loads set to elicit the same relative cardiac strain in both their hot and cool training conditions and also found that none of the heat adaptations (eg, increased PV) correlated to changes in exercise performance. Indeed, although not always shown, increased training load or multi‐day competition in already hypervolemic elite endurance athletes (international level cyclists) has been shown to augment PV by 5%‐20% in as little as 6‐7 days regardless of the heat load . Importantly, the current study's outcomes, in combination with training effects on PV, suggest that many of the previously published HA studies without an exercise control group in mild/cool conditions matched for relative cardiac work stress, may be showing outcomes that are due to both exercise stress, and metabolic heat.…”

A step towards removing plasma volume variance from the Athlete's Biological Passport: The use of biomarkers to describe vascular volumes from a simple blood test

“…Biomarkers to adjust for vascular shifts present an alternative approach. Previously, ALB was identified as a candidate PV marker ; however, ALB is influenced by altitude, exercise and nutritional status . As such, it is unlikely that an individual marker will present with sufficient stability and low variability, which would be required to accurately and reliably identify PV shifts in an anti‐doping context.…”