Acute hyperhydration reduces athlete biological passport OFF-hr score

Establishing Personalized Blood Protein Reference Ranges Using Noninvasive Microsampling and Targeted Proteomics: Implications for Antidoping Strategies

To prevent doping practices in sports, the World Anti-Doping Agency implemented the Athlete Biological Passport (ABP) program, monitoring biological variables over time to indirectly reveal the effects of doping rather than detect the doping substance or the method itself. In the context of this program, a highly multiplexed mass spectrometry-based proteomics assay for 319 peptides corresponding to 250 proteins was developed, including proteins associated with blood-doping practices. "Baseline" expression profiles of these potential biomarkers in capillary blood (dried blood spots (DBS)) were established using multiple reaction monitoring (MRM). Combining DBS microsampling with highly multiplexed MRM assays is the best-suited technology to enhance the effectiveness of the ABP program, as it represents a cost-effective and robust alternative analytical method with high specificity and selectivity of targets in the attomole range. DBS data were collected from 10 healthy athlete volunteers over a period of 140 days (28 time points per participant). These comprehensive findings provide a personalized targeted blood proteome "fingerprint" showcasing that the targeted proteome is unique to an individual and likely comparable to a DNA fingerprint. The results can serve as a baseline for future studies investigating doping-related perturbations.

Contemporary blood doping-Performance, mechanism, and detection

Blood doping is prohibited for athletes but has been a well-described practice within endurance sports throughout the years. With improved direct and indirect detection methods, the practice has allegedly moved towards micro-dosing, that is, reducing the blood doping regime amplitude. This narrative review evaluates whether blood doping, specifically recombinant human erythropoietin (rhEpo) treatment and blood transfusions are performance-enhancing, the responsible mechanism as well as detection possibilities with a special emphasis on micro-dosing. In general, studies evaluating micro-doses of blood doping are limited. However, in randomized, double-blinded, placebo-controlled trials, three studies find that infusing as little as 130 ml red blood cells or injecting 9 IU × kg bw-1 rhEpo three times per week for 4 weeks improve endurance performance ~4%-6%. The responsible mechanism for a performance-enhancing effect following rhEpo or blood transfusions appear to be increased O2 -carrying capacity, which is accompanied by an increased muscular O2 extraction and likely increased blood flow to the working muscles, enabling the ability to sustain a higher exercise intensity for a given period. Blood doping in micro-doses challenges indirect detection by the Athlete Biological Passport, albeit it can identify ~20%-60% of the individuals depending on the sample timing. However, novel biomarkers are emerging, and some may provide additive value for detection of micro blood doping such as the immature reticulocytes or the iron regulatory hormones hepcidin and erythroferrone. Future studies should attempt to validate these biomarkers for implementation in real-world anti-doping efforts and continue the biomarker discovery.

Changes in Immature Reticulocytes Aid the Indirect Detection of Microdose Recombinant Erythropoietin Use in Men and Women

PURPOSE

We investigated whether immature reticulocyte fraction (IRF) and the immature reticulocytes to red blood cells ratio (IR/RBC) are sensitive and specific biomarkers for microdose recombinant human erythropoietin (rHuEPO) and whether the inclusion of reticulocyte percentage (RET%) and the algorithm "abnormal blood profile score (ABPS)" increased the athlete biological passport (ABP) sensitivity compared with hemoglobin concentration ([Hb]) and the OFF-hr score ([Hb]-60 × √RET%).

METHODS

Forty-eight (♀ = 24, ♂ = 24) participants completed a 2-wk baseline period followed by a 4-wk intervention period with three weekly intravenous injections of 9 IU·kg -1 ·bw -1 epoetin β (♀ = 12, ♂ = 12) or saline (0.9% NaCl, ♀ = 12, ♂ = 12) and a 10-d follow-up. Blood samples were collected weekly during baseline and intervention as well as 3, 5, and 10 d after treatment.

RESULTS

The rHuEPO treatment increased [Hb] (time-treatment, P < 0.001), RET% (time-treatment, P < 0.001), IRF (time-treatment, P < 0.001) and IR/RBC (time-treatment, P < 0.001). IRF and IR/RBC were up to ~58% ( P < 0.001) and ~141% ( P < 0.001) higher compared with placebo, and calculated thresholds provided a peak sensitivity across timepoints of 58% and 54% with ~98% specificity, respectively. To achieve >99% specificity for IRF and IR/RBC, sensitivity was reduced to 46% and 50%, respectively. Across all timepoints, the addition of RET% and ABPS to the ABP increased sensitivity from 29% to 46%. Identification of true-positive outliers obtained via the ABP and IRF and IR/RBC increased sensitivity across all timepoints to 79%.

CONCLUSIONS

In summary, IRF, IR/RBC, RET% and ABPS are sensitive and specific biomarkers for microdose rHuEPO in both men and women and complement the ABP.

Altitude and Erythropoietin: Comparative Evaluation of Their Impact on Key Parameters of the Athlete Biological Passport: A Review

The hematological module of the Athlete's Biological Passport (ABP) identifies doping methods and/or substances used to increase the blood's capacity to transport or deliver oxygen to the tissues. Recombinant human erythropoietin (rhEPOs) are doping substances known to boost the production of red blood cells and might have an effect on the blood biomarkers of the ABP. However, hypoxic exposure influences these biomarkers similarly to rhEPOs. This analogous impact complicates the ABP profiles' interpretation by antidoping experts. The present study aimed to collect and identify, through a literature search, the physiological effects on ABP blood biomarkers induced by these external factors. A total of 43 studies were selected for this review. A positive correlation (R² = 0.605, r = 0.778, p < 0.001) was identified between the hypoxic dose and the increase in hemoglobin concentration (HGB) percentage. In addition, the change in the reticulocyte percentage (RET%) has been identified as one of the most sensitive parameters to rhEPO use. The mean effects of rhEPO on blood parameters were greater than those induced by hypoxic exposure (1.7 times higher for HGB and RET% and 4 times higher for hemoglobin mass). However, rhEPO micro-doses have shown effects that are hardly distinguishable from those identified after hypoxic exposure. The results of the literature search allowed to identify temporal and quantitative evolution of blood parameters in connection with different hypoxic exposure doses, as well as different rhEPOs doses. This might be considered to provide justified and well-documented interpretations of physiological changes in blood parameters of the Athlete Biological Passport.

Untargeted Metabolomics Identifies a Novel Panel of Markers for Autologous Blood Transfusion

Untargeted metabolomics was used to analyze serum and urine samples for biomarkers of autologous blood transfusion (ABT). Red blood cell concentrates from donated blood were stored for 35−36 days prior to reinfusion into the donors. Participants were sampled at different time points post-donation and up to 7 days post-transfusion. Metabolomic profiling was performed using ACQUITY ultra performance liquid chromatography (UPLC), Q-Exactive high resolution/accurate mass spectrometer interfaced with a heated electrospray ionization (HESI-II) source and Orbitrap mass analyzer operated at 35,000 mass resolution. The markers of ABT were determined by principal component analysis and metabolites that had p < 0.05 and met ≥ 2-fold change from baseline were selected. A total of 11 serum and eight urinary metabolites, including two urinary plasticizer metabolites, were altered during the study. By the seventh day post-transfusion, the plasticizers had returned to baseline, while changes in nine other metabolites (seven serum and two urinary) remained. Five of these metabolites (serum inosine, guanosine and sphinganine and urinary isocitrate and erythronate) were upregulated, while serum glycourdeoxycholate, S-allylcysteine, 17-alphahydroxypregnenalone 3 and Glutamine conjugate of C6H10O2 (2)* were downregulated. This is the first study to identify a panel of metabolites, from serum and urine, as markers of ABT. Once independently validated, it could be universally adopted to detect ABT.

Tracking immature reticulocyte proteins for improved detection of recombinant human erythropoietin (rhEPO) abuse

Athletes abuse recombinant human erythropoietin (rhEPO) and erythropoiesis stimulating agents to increase hemoglobin mass and improve performance. To evade detection, athletes have developed sophisticated blood doping regimens, which often include rhEPO micro-dosing. Detection of these methods requires biomarkers with increased sensitivity and a sample matrix that is more amenable to frequent testing in the field. We have developed a method to measure two immature reticulocyte proteins, CD71 and ferrochelatase (FECH), and one total erythrocyte protein, Band 3, in dried blood spots (DBS). This method was tested in response to rhEPO administration after low doses, 40 IU/kg, micro-doses, 900 IU, or saline injection in 20 healthy subjects. During administration of low-dose rhEPO, the mean CD71/Band 3 and FECH/Band 3 ratio increased by 412 ± 197% and 250 ± 44%, respectively. The mean response for the current biomarker, RET%, increased by 195 ± 35%. During administration of rhEPO micro-doses, CD71/Band 3 increased to 127 ± 25% on day 35 and 139 ± 36% on day 39, while no increase was observed in RET%. After rhEPO administration, during the washout phase, mean values decreased to a minimum of 64 ± 4% and 64 ± 11% for CD71/Band 3 and RET%, respectively. However, CD71/Band 3 remained below 75% of baseline for at least 4 weeks after rhEPO injection, while RET% returned to baseline levels. The results demonstrate that immature reticulocyte proteins have a larger response to rhEPO administration than the current biomarker, RET%, and can be monitored in the DBS matrix.

Factors Confounding the Athlete Biological Passport: A Systematic Narrative Review

BACKGROUND

Through longitudinal, individual and adaptive monitoring of blood biomarkers, the haematological module of the athlete biological passport (ABP) has become a valuable tool in anti-doping efforts. The composition of blood as a vector of oxygen in the human body varies in athletes with the influence of multiple intrinsic (genetic) or extrinsic (training or environmental conditions) factors. In this context, it is fundamental to establish a comprehensive understanding of the various causes that may affect blood variables and thereby alter a fair interpretation of ABP profiles.

METHODS

This literature review described the potential factors confounding the ABP to outline influencing factors altering haematological profiles acutely or chronically.

RESULTS

Our investigation confirmed that natural variations in ABP variables appear relatively small, likely-at least in part-because of strong human homeostasis. Furthermore, the significant effects on haematological variations of environmental conditions (e.g. exposure to heat or hypoxia) remain debatable. The current ABP paradigm seems rather robust in view of the existing literature that aims to delineate adaptive individual limits. Nevertheless, its objective sensitivity may be further improved.

CONCLUSIONS

This narrative review contributes to disentangling the numerous confounding factors of the ABP to gather the available scientific evidence and help interpret individual athlete profiles.

Measurement of Immature Reticulocytes in Dried Blood Spots by Mass Spectrometry

BACKGROUND

Immature reticulocytes (IRC) are the first cells to respond to changes in erythropoiesis. For antidoping applications, measurement of IRC may improve detection of blood doping practices. Unfortunately, this small cell population has limited stability in liquid blood samples and is difficult to measure with optimal precision. We developed a method to measure 3 IRC membrane proteins in dried blood spots (DBS) to monitor changes in erythropoiesis.

METHODS

DBS spots were washed with buffers to remove soluble proteins, membrane proteins remaining in the spot were digested with trypsin, and one peptide for each protein was measured by LC-MS/MS. IRC protein concentration was determined using a DBS single point calibrator.

RESULTS

Intraassay precision for IRC proteins was between 5%-15%. IRC proteins were stable in DBS for 29 days at room temperature. In a longitudinal study of 25 volunteers, the mean intraindividual variation for 3 IRC proteins was 17%, 20%, and 24% from capillary blood DBS. In comparison, the mean longitudinal variation for IRC counts measured on an automated hematology analyzer was 38%. IRC protein concentration from capillary blood DBS correlated well with venous blood DBS protein concentrations.

CONCLUSIONS

Measurement of IRC proteins in DBS samples provides a method to measure changes in erythropoiesis with improved analytical sensitivity, stability, and precision. When combined with the inherent advantages of capillary blood collection in the field, this method may substantially improve the detection of blood doping practices.

On the trail of blood doping-microRNA fingerprints to monitor autologous blood transfusions in vivo

Autologous blood doping refers to the illegal re-transfusion of any quantities of blood or blood components with blood donor and recipient being the same person. The re-transfusion of stored erythrocyte concentrates is particularly attractive to high-performance athletes as this practice improves their oxygen capacity excessively. However, there is still no reliable detection method available. Analyzing circulating microRNA profiles of human subjects that underwent monitored autologous blood transfusions seems to be a highly promising approach to develop novel biomarkers for autologous blood doping. In this exploratory study, we randomly divided 30 healthy males into two different treatment groups and one control group and sampled whole blood at several time points at baseline, after whole blood donation and after transfusion of erythrocyte concentrates. Hematological variables were recorded and analyzed following the adaptive model of the Athlete Biological Passport. microRNA profiles were examined by small RNA sequencing and comprehensive multivariate data analyses, revealing microRNA fingerprints that reflect the sampling time point and transfusion volume. Neither individual microRNAs nor a signature of transfusion-dependent microRNAs reached superior sensitivity at 100% specificity compared to the Athlete Biological Passport (≤11% 6 h after transfusion versus ≤44% 2 days after transfusion). However, the window of autologous blood doping detection was different. Due to the heterogenous nature of doping, with athletes frequently combining multiple medications in order to both gain a competitive advantage and interfere with known testing methods, the true applicability of the molecular signature remains to be validated in real anti-doping testings.

An Untargeted Urine Metabolomics Approach for Autologous Blood Transfusion Detection

PURPOSE

Autologous blood transfusion is performance enhancing and prohibited in sport but remains difficult to detect. This study explored the hypothesis that an untargeted urine metabolomics analysis can reveal one or more novel metabolites with high sensitivity and specificity for detection of autologous blood transfusion.

METHODS

In a randomized, double-blinded, placebo-controlled, crossover design, exercise-trained men (n = 12) donated 900 mL blood or were sham phlebotomized. After 4 wk, red blood cells or saline were reinfused. Urine samples were collected before phlebotomy and 2 h and 1, 2, 3, 5, and 10 d after reinfusion and analyzed by ultraperformance liquid chromatography-quadrupole time-of-flight mass spectrometry. Models of unique metabolites reflecting autologous blood transfusion were attained by partial least-squares discriminant analysis.

RESULTS

The strongest model was obtained 2 h after reinfusion with a misclassification error of 6.3% and 98.8% specificity. However, combining only a few of the strongest metabolites selected by this model provided a sensitivity of 100% at days 1 and 2 and 66% at day 3 with 100% specificity. Metabolite identification revealed the presence of secondary di-2-ethylhexyl phtalate metabolites and putatively identified the presence of (iso)caproic acid glucuronide as the strongest candidate biomarker.

CONCLUSIONS

Untargeted urine metabolomics revealed several plasticizers as the strongest metabolic pattern for detection of autologous blood transfusion for up to 3 d. Importantly, no other metabolites in urine seem of value for antidoping purposes.

Diurnal variation in red blood cell variables in athletes after single and repeated bouts of exercise

BACKGROUND

The aim of this study was to examine the diurnal and exercise-related changes in red blood cell variables which serve as indirect markers of doping in sports.

METHODS

Ten men and 7 women, all undoped highly trained endurance athletes aged 19-34 years, were included in the study. Before and on the day with single and repeated bouts of exercise, blood samples were collected at 07:00, 09:00, 13:00, 18:00, and 21:00, at least 2 hours after exercise. Hemoglobin (Hb), hematocrit (Hct), and the reticulocytes % (Ret%) were determined by flow cytometry. Changes in OFF-hr score were also calculated and repeated-measures ANOVA was used to compare diurnal differences.

RESULTS

In overall, the mean Hb decreased continuously by 4.5 and 3.3% (all P<0.001) over the day with single and repeated bouts of exercise, respectively. Corresponding values for the decline in Hct were 4.2 and 5.9% (all P<0.001). In contrast, the Ret% showed no apparent diurnal rhythm but single and repeated bouts of exercise increased the relative Ret% in the evening by 12.4 and 16.7% (P<0.01), respectively. Then the calculated OFF-hr score was reduced by 6.2 and 9.8% (all P<0.01) at the end of the day.

CONCLUSIONS

These results confirmed the normal diurnal pattern in the examined red blood cell variables in response to exercise in highly trained athletes. Furthermore, they showed noticeable between-subject variability and the possible risk of a false suspicion of blood doping in undoped athletes after repeated bouts of exercise.

Hematological adaptations and detection of recombinant human erythropoietin combined with chronic hypoxia

This study evaluated whether recombinant human erythropoietin (rhEpo) treatment combined with chronic hypoxia provided an additive erythropoietic response and whether the athlete biological passport (ABP) sensitivity improved with hypoxia. Two interventions were completed, each containing 4 weeks baseline, 4 weeks exposure at sea level or 2,320 m of altitude, and 4 weeks follow-up. Participants were randomly assigned to 20 IU·kg bw^-1 rhEpo or placebo injections every second day for 3 weeks during the exposure period at sea level (rhEpo n = 25, placebo n = 9) or at altitude (rhEpo n = 12, placebo n = 27). Venous blood was analyzed weekly. Combining rhEpo and hypoxia induced larger changes compared with rhEpo or hypoxia alone for [Hb] (p < 0.001 and p > 0.05, respectively), reticulocyte percentage (p < 0.001), and OFF-hr score (p < 0.01 and p < 0.001, respectively). The most pronounced effect was observed for reticulocyte percentage with up to ~35% (p < 0.001) and ~45% (p < 0.001) higher levels compared with rhEpo or hypoxia only, respectively. The ABP sensitivity for the combined treatment was 54 and 35 percentage points higher for [Hb] (p < 0.05) and reticulocyte percentage (p < 0.05), respectively, but similar for OFF-hr score, compared with rhEpo at sea level. Across any time point, [Hb] and OFF-hr score combined identified 14 unique true-positive participants (56%) at sea level and 12 unique true-positive participants (100%) at altitude. However, a concurrent reduction in specificity existed at altitude. In conclusion, rhEpo treatment combined with hypoxic exposure provided an additive erythropoietic response compared with rhEpo or hypoxic exposure alone. Correspondingly, ABP was more sensitive to rhEpo at altitude than at sea level, but a compromised specificity existed with hypoxic exposure.

The Influence of Floorball on Hematological Parameters: Consequences in Health Assessment and Antidoping Testing

Assessment of hematological parameters is common in sports medicine. Although physical exercise is an important preanalytical variable, data about acute hematological changes after high-intensity intermittent exercise are scarce. This study aimed to examine floorball as a potential preanalytical variable for hematological parameters used in health assessment and antidoping testing. Twenty-three professional male floorball players participated in a floorball game. Hematological parameters including hemoglobin, erythrocyte count and erythrocyte indices, reticulocytes, white blood cells (WBC), platelets, reticulocytes, and OFF-hr score were assessed at baseline, immediately postgame, and at 2 h postgame. Median hemoglobin concentration decreased significantly from 146 g/L pregame to 141 g/L immediately postgame (p < 0.001). WBC count increased from 7.2 × 10⁹/L pregame to 10.1 × 10⁹/L 2 h postgame (p < 0.001). The median OFF-hr score decreased from 99.5 to 94.2 immediately postgame and remained significantly lower than baseline at 2 h postgame (94.4, p=0.030). Looking at individual results, the highest OFF-hr score increased from 120 at baseline to 124 at 2 h postgame. Our findings suggest that participation in a floorball game affects several hematological parameters and consequently can affect health assessment and antidoping testing.

Z-scores-based methods and their application to biological monitoring: an example in professional soccer players

The clinical and biological follow-up of individuals, such as the biological passport for athletes, is typically based on the individual and longitudinal monitoring of hematological or urine markers. These follow-ups aim to identify abnormal behavior by comparing the individual's biological samples to an established baseline. These comparisons may be done via different ways, but each of them requires an appropriate extra population to compute the significance levels, which is a non-trivial issue. Moreover, it is not necessarily relevant to compare the measures of a biomarker of a professional athlete to that of a reference population (even restricted to other athletes), and a reasonable alternative is to detect the abnormal values by considering only the other measurements of the same athlete. Here we propose a simple adaptive statistic based on maxima of Z-scores that does not rely on the use of an extra population. We show that, in the Gaussian framework, it is a practical and relevant method for detecting abnormal values in a series of observations from the same individual. The distribution of this statistic does not depend on the individual parameters under the null hypothesis, and its quantiles can be computed using Monte Carlo simulations. The proposed method is tested on the 3-year follow-up of ferritin, serum iron, erythrocytes, hemoglobin, and hematocrit markers in 2577 elite male soccer players. For instance, if we consider the abnormal values for the hematocrit at a 5% level, we found that 5.57% of the selected cohort had at least one abnormal value (which is not significantly different from the expected false-discovery rate). The approach is a starting point for more elaborate models that would produce a refined individual baseline. The method can be extended to the Gaussian linear model, in order to include additional variables such as the age or exposure to altitude. The method could also be applied to other domains, such as the clinical patient follow-up in monitoring abnormal values of biological markers.

Assessing serum albumin concentration following exercise-induced fluid shifts in the context of the athlete biological passport

PURPOSE

The hydration status of an athlete at the time of a doping control sample collection is an important factor to consider when reviewing athlete biological passports (ABPs). Dehydration results in a reduction of the circulating plasma volume (PV), which may lead to artificially high values of some blood parameters. This study aimed to identify whether serum albumin could serve as a single marker of fluid shifts, which are not currently accounted for in the hematological passport. An additional marker could be used to assist experts when interpreting irregularities in the ABP.

METHODS

Twelve subjects underwent multiple controlled exercise trials designed to induce varying levels of PV shifts. Pre-exercise blood samples were collected to establish baseline values for individual passports. During exercise interventions, blood samples were collected before the start of exercise and at 10 minute, 1 hour, 2 hours, and 24 hours following exercise.

RESULTS

Significant increases in hematological parameters - hemoglobin [Hb], hematocrit (HCT), albumin (ALB), and calculated OFF-score - were identified at varying time points following fluid shift-inducing exercise. Changes in ALB correlated strongly with changes in [Hb] (r = 0.753) and with estimated PV shifts (r = -0.764). In analyzing ABPs, the resulting increases in Hb did not trigger any atypical findings at 99% specificity.

PERSPECTIVE

Monitoring changes in ALB longitudinally may assist experts when reviewing PV shifts in the biological passport.

The need for an alternative method to determine intravascular volumes

It is well described that numerous environmental factors, including exercise, modulate plasma volume (PV). These modulations prove problematic when a number of haematological markers are measured as a concentration in blood plasma. A primary example is haemoglobin concentration ([Hb]), a marker of erythropoiesis commonly used within medicine and also used to detect blood doping. Natural changes in PV can confound [Hb] values when a volume change is detected rather than a true change in haemoglobin mass (Hb_mass) (e.g. volume expansion resulting in a [Hb] decrease and pseudo-anemia vs. Hb_mass decline resulting in anaemia). Currently, there is no simple solution to correct for PV shifts, and this has proven problematic when monitoring volumetric health markers in clinical and anti-doping settings. This narrative review explores the influence that PV shifts have on volumetric biomarkers, such as [Hb]. The progressive expansion in PV observed during multi-day endurance events will be summarised, and the observed impact PV variance has on concentration-based markers will be quantified. From this, the need for alternative methods to correct [Hb] for volume fluctuations is highlighted. Available methods for calculating intravascular volumes are then discussed, with a focus on a recently developed approach using a panel of 'volume descriptive' biomarkers from a standard blood test. Finally, the practical applications of this novel PV blood test within both anti-doping and clinical settings will be examined.

The Critical Power Model as a Potential Tool for Anti-doping

Existing doping detection strategies rely on direct and indirect biochemical measurement methods focused on detecting banned substances, their metabolites, or biomarkers related to their use. However, the goal of doping is to improve performance, and yet evidence from performance data is not considered by these strategies. The emergence of portable sensors for measuring exercise intensities and of player tracking technologies may enable the widespread collection of performance data. How these data should be used for doping detection is an open question. Herein, we review the basis by which performance models could be used for doping detection, followed by critically reviewing the potential of the critical power (CP) model as a prototypical performance model that could be used in this regard. Performance models are mathematical representations of performance data specific to the athlete. Some models feature parameters with physiological interpretations, changes to which may provide clues regarding the specific doping method. The CP model is a simple model of the power-duration curve and features two physiologically interpretable parameters, CP and W′. We argue that the CP model could be useful for doping detection mainly based on the predictable sensitivities of its parameters to ergogenic aids and other performance-enhancing interventions. However, our argument is counterbalanced by the existence of important limitations and unresolved questions that need to be addressed before the model is used for doping detection. We conclude by providing a simple worked example showing how it could be used and propose recommendations for its implementation.

Validation of a blood marker for plasma volume in endurance athletes during a live-high train-low altitude training camp

Altitude is a confounding factor within the Athlete Biological Passport (ABP) due, in part, to the plasma volume (PV) response to hypoxia. Here, a newly developed PV blood test is applied to assess the possible efficacy of reducing the influence of PV on the volumetric ABP markers; haemoglobin concentration ([Hb]) and the OFF-score. Endurance athletes (n=34) completed a 21-night simulated live-high train-low (LHTL) protocol (14 h.d-1 at 3000 m). Bloods were collected twice pre-altitude; at days 3, 8, and 15 at altitude; and 1, 7, 21, and 42 days post-altitude. A full blood count was performed on the whole blood sample. Serum was analysed for transferrin, albumin, calcium, creatinine, total protein, and low-density lipoprotein. The PV blood test (consisting of the serum markers, [Hb] and platelets) was applied to the ABP adaptive model and new reference predictions were calculated for [Hb] and the OFF-score, thereby reducing the PV variance component. The PV correction refined the ABP reference predictions. The number of atypical passport findings (ATPFs) for [Hb] was reduced from 7 of 5 subjects to 6 of 3 subjects. The OFF-score ATPFs increased with the PV correction (from 9 to 13, 99% specificity); most likely the result of more specific reference limit predictions combined with the altitude-induced increase in red cell production. Importantly, all abnormal biomarker values were identified by a low confidence value. Although the multifaceted, individual physiological response to altitude confounded some results, the PV model appears capable of reducing the impact of PV fluctuations on [Hb].

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

The haematological module of the Athlete's Biological Passport (ABP) has significantly impacted the prevalence of blood manipulations in elite sports. However, the ABP relies on a number of concentration-based markers of erythropoiesis, such as haemoglobin concentration ([Hb]), which are influenced by shifts in plasma volume (PV). Fluctuations in PV contribute to the majority of biological variance associated with volumetric ABP markers. Our laboratory recently identified a panel of common chemistry markers (from a simple blood test) capable of describing ca 67% of PV variance, presenting an applicable method to account for volume shifts within anti-doping practices. Here, this novel PV marker was included into the ABP adaptive model. Over a six-month period (one test per month), 33 healthy, active males provided blood samples and performed the CO-rebreathing method to record PV (control). In the final month participants performed a single maximal exercise effort to promote a PV shift (mean PV decrease -17%, 95% CI -9.75 to -18.13%). Applying the ABP adaptive model, individualized reference limits for [Hb] and the OFF-score were created, with and without the PV correction. With the PV correction, an average of 66% of [Hb] within-subject variance is explained, narrowing the predicted reference limits, and reducing the number of atypical ABP findings post-exercise. Despite an increase in sensitivity there was no observed loss of specificity with the addition of the PV correction. The novel PV marker presented here has the potential to improve the ABP's rate of correct doping detection by removing the confounding effects of PV variance.

Autologous Doping with Cryopreserved Red Blood Cells - Effects on Physical Performance and Detection by Multivariate Statistics

The discovery of erythropoietin (EPO) simplified blood doping in sports, but improved detection methods, for EPO has forced cheating athletes to return to blood transfusion. Autologous blood transfusion with cryopreserved red blood cells (RBCs) is the method of choice, because no valid method exists to accurately detect such event. In endurance sports, it can be estimated that elite athletes improve performance by up to 3% with blood doping, regardless of method. Valid detection methods for autologous blood doping is important to maintain credibility of athletic performances. Recreational male (N = 27) and female (N = 11) athletes served as Transfusion (N = 28) and Control (N = 10) subjects in two different transfusion settings. Hematological variables and physical performance were measured before donation of 450 or 900 mL whole blood, and until four weeks after re-infusion of the cryopreserved RBC fraction. Blood was analyzed for transferrin, iron, Hb, EVF, MCV, MCHC, reticulocytes, leucocytes and EPO. Repeated measures multivariate analysis of variance (MANOVA) and pattern recognition using Principal Component Analysis (PCA) and Orthogonal Projections of Latent Structures (OPLS) discriminant analysis (DA) investigated differences between Control and Transfusion groups over time. Significant increase in performance (15 ± 8%) and VO2max (17 ± 10%) (mean ± SD) could be measured 48 h after RBC re-infusion, and remained increased for up to four weeks in some subjects. In total, 533 blood samples were included in the study (Clean = 220, Transfused = 313). In response to blood transfusion, the largest change in hematological variables occurred 48 h after blood donation, when Control and Transfused groups could be separated with OPLS-DA (R2 = 0.76/Q2 = 0.59). RBC re-infusion resulted in the best model (R2 = 0.40/Q2 = 0.10) at the first sampling point (48 h), predicting one false positive and one false negative. Over all, a 25% and 86% false positives ratio was achieved in two separate trials. In conclusions, autologous re-infusion of RBCs increased VO2max and performance as hypothesized, but hematological profiling by multivariate statistics could not reach the WADA stipulated false positive ratio of <0.001% at any time point investigated. A majority of samples remained within limits of normal individual variation at all times.