Physiological differences between normobaric and hypobaric hypoxia

Altitude training is frequently used by elites athletes. Several hypoxic methods have been developed to improve sea-level performances and the Live High-Train Low approach, where athletes live and sleep at altitudes between 2200 and 2500 m and train under 1200 m is recognized as effective. Recent research focused on the potential differences between normobaric (NH) and hypobaric hypoxia (HH), i.e. simulated and real altitudes. Slight physiological differences have been found between either acute or chronic hypoxic exposure in NH and HH. Taken together, these differences intimate larger physiological responses to hypoxic exposure in "terrestrial" (i.e. HH) versus "simulated" altitudes (i.e. NH). However, there is not a sufficient body of knowledge to confirm if one hypoxic condition could induce larger performance enhancement than the other, either during or after acute hypoxic exposure or altitude camps (i.e. chronic hypoxic exposure). Many confounding factors and the large inter- individual variability to hypoxic exposure make the comparison very challenging. Consequently, we first designed a crossover study to assess these potential differences and confirmed for the first time with direct comparison on the same subjects that HH induces different physiological adaptations compared to NH during a 3 weeks LHTL camp. However, physiological differences were not clinically sufficient to induce sea-level performance disparities. Secondly, we showed that acute high altitude hypobaric hypoxia (24h, 3450 m) is more demanding than normobaric hypoxia and induces larger performance impairments on a 250-kJ cycle time trial. Finally, our work demonstrated that sleep is further disturbed in HH compared to NH in both acute and chronic hypoxia. As previously suggested, HH seems to be a more stressful stimulus than NH at iso-PiO2. Consequently, NH and HH should not be used interchangeably and the main factor seems to be the lower peripheral oxygen saturation in HH at rest, as well as during exercise

A new multimodal paradigm for biomarkers longitudinal monitoring: a clinical application to women steroid profiles in urine and blood.

Most current state-of-the-art strategies to generate individual adaptive reference ranges are designed to monitor one clinical parameter at a time. An innovative methodology is proposed for the simultaneous longitudinal monitoring of multiple biomarkers. The estimation of individual thresholds is performed by applying a Bayesian modeling strategy to a multivariate score integrating several biomarkers (compound concentration and/or ratio). This multimodal monitoring was applied to data from a clinical study involving 14 female volunteers with normal menstrual cycles receiving testosterone via transdermal route, as to test its ability to detect testosterone administration. The study samples consisted of urine and blood collected during 4 weeks of a control phase and 4 weeks with a daily testosterone gel application. Integrating multiple biomarkers improved the detection of testosterone gel administration with substantially higher sensitivity compared with the distinct follow-up of each biomarker, when applied to selected urine and serum steroid biomarkers, as well as the combination of both. Among the 175 known positive samples, 38% were identified by the multimodal approach using urine biomarkers, 79% using serum biomarkers and 83% by combining biomarkers from both biological matrices, whereas 10%, 67% and 64% were respectively detected using standard unimodal monitoring. The detection of abnormal patterns can be improved using multimodal approaches. The combination of urine and serum biomarkers reduced the overall number of false-negatives, thus evidencing promising complementarity between urine and blood sampling for doping control, as highlighted in the case of the use of transdermal testosterone preparations. The generation in a multimodal setting of adaptive and personalized reference ranges opens up new opportunities in clinical and anti-doping profiling. The integration of multiple parameters in a longitudinal monitoring is expected to provide a more complete evaluation of individual profiles generating actionable intelligence to further guide sample collection, analysis protocols and decision-making in clinics and anti-doping

Detection of testosterone administration based on the carbon isotope ratio profiling of endogenous steroids: international reference populations of professional soccer players

BACKGROUND AND OBJECTIVES: The determination of the carbon isotope ratio in androgen metabolites has been previously shown to be a reliable, direct method to detect testosterone misuse in the context of antidoping testing. Here, the variability in the 13C/12C ratios in urinary steroids in a widely heterogeneous cohort of professional soccer players residing in different countries (Argentina, Italy, Japan, South Africa, Switzerland and Uganda) is examined. METHODS: Carbon isotope ratios of selected androgens in urine specimens were determined using gas chromatography/combustion/isotope ratio mass spectrometry (GC-C-IRMS). RESULTS: Urinary steroids in Italian and Swiss populations were found to be enriched in 13C relative to other groups, reflecting higher consumption of C3 plants in these two countries. Importantly, detection criteria based on the difference in the carbon isotope ratio of androsterone and pregnanediol for each population were found to be well below the established threshold value for positive cases. CONCLUSIONS: The results obtained with the tested diet groups highlight the importance of adapting the criteria if one wishes to increase the sensitivity of exogenous testosterone detection. In addition, confirmatory tests might be rendered more efficient by combining isotope ratio mass spectrometry with refined interpretation criteria for positivity and subject-based profiling of steroids

Alterations of Neuromuscular Function after the World's Most Challenging Mountain Ultra-Marathon.

We investigated the physiological consequences of the most challenging mountain ultra-marathon (MUM) in the world: a 330-km trail run with 24000 m of positive and negative elevation change. Neuromuscular fatigue (NMF) was assessed before (Pre-), during (Mid-) and after (Post-) the MUM in experienced ultra-marathon runners (n = 15; finish time  = 122.43 hours ±17.21 hours) and in Pre- and Post- in a control group with a similar level of sleep deprivation (n = 8). Blood markers of muscle inflammation and damage were analyzed at Pre- and Post-. Mean ± SD maximal voluntary contraction force declined significantly at Mid- (-13±17% and -10±16%, P<0.05 for knee extensor, KE, and plantar flexor muscles, PF, respectively), and further decreased at Post- (-24±13% and -26±19%, P<0.01) with alteration of the central activation ratio (-24±24% and -28±34% between Pre- and Post-, P<0.05) in runners whereas these parameters did not change in the control group. Peripheral NMF markers such as 100 Hz doublet (KE: -18±18% and PF: -20±15%, P<0.01) and peak twitch (KE: -33±12%, P<0.001 and PF: -19±14%, P<0.01) were also altered in runners but not in controls. Post-MUM blood concentrations of creatine kinase (3719±3045 Ul·(1)), lactate dehydrogenase (1145±511 UI·L(-1)), C-Reactive Protein (13.1±7.5 mg·L(-1)) and myoglobin (449.3±338.2 µg·L(-1)) were higher (P<0.001) than at Pre- in runners but not in controls. Our findings revealed less neuromuscular fatigue, muscle damage and inflammation than in shorter MUMs. In conclusion, paradoxically, such extreme exercise seems to induce a relative muscle preservation process due likely to a protective anticipatory pacing strategy during the first half of MUM and sleep deprivation in the second half

Worldwide distribution of blood values in elite track and field athletes: Biomarkers of altered erythropoiesis.

For the first time, blood samples were collected in all athletes participating in a major sporting event of the International Association of Athletics Federations (IAAF) (Athletics World Championships 2011, Daegu, Korea). All variables obtained from blood analyses were incorporated into the individual blood profiles of each athlete for the so-called athlete biological passport (ABP). This unprecedented data collection highlighted differences for a few blood biomarkers commonly measured and reported for the ABP on some group of athletes. Subsequently, blood tests analyses for all athletes were repeated during the following World Championships (2013, Moscow, Russia). Both sets of blood tests were then used to set up the distribution of blood values for track and field athletes considering potential confounding factors such as gender, age, discipline, origin of the athlete (continental classification), and time of blood collection. Implementation of well-defined distribution of blood values will allow to improve the estimation of blood doping prevalence among a specific population of athletes in track and field

Steroid profiling by UHPLC-MS/MS in dried blood spots collected from healthy women with and without testosterone gel administration.

The quantification of a large panel of endogenous steroids in serum by LC-MS/MS represents a powerful clinical tool for the screening or diagnosis of diverse endocrine disorders. This approach has also demonstrated excellent sensitivity for the detection of testosterone misuse in the anti-doping field, especially in female athlete population. In both situations, the use of dried blood spots (DBS) could provide a viable alternative to invasive venous blood collection. Here, the evaluation of DBS sampling for the quantification of a panel of endogenous steroids using UHPLC-MS/MS is described. The UHPLC-MS/MS method was validated for quantitative analysis of eleven free and eight conjugated steroids and was then used for the analysis of DBS samples collected in 14 healthy women during a normal menstrual cycle (control phase) followed by a 28-days testosterone gel treatment (treatment phase). Results were compared with those obtained from serum matrix. Satisfactory performance was obtained for all compounds in terms of selectivity, linearity, accuracy, precision, combined uncertainty, stability as well as extraction recovery and matrix effects. In control phase, high correlation was observed between DBS and serum concentrations for most compounds. In treatment phase, higher testosterone concentrations were observed in capillary than in venous DBS, suggesting a possible interference resulting from testosterone contamination on finger(s) used for gel application. Steroid profiling in capillary DBS represents a simple and efficient strategy for monitoring endogenous steroid concentrations and their fluctuation in clinical context of steroid-related disorders, or for the detection of testosterone abuse in anti-doping

Prooxidant/Antioxidant Balance in Hypoxia: A Cross-Over Study on Normobaric vs. Hypobaric “Live High-Train Low”

“Live High-Train Low” (LHTL) training can alter oxidative status of athletes. This study compared prooxidant/antioxidant balance responses following two LHTL protocols of the same duration and at the same living altitude of 2250 m in either normobaric (NH) or hypobaric (HH) hypoxia. Twenty-four well-trained triathletes underwent the following two 18-day LHTL protocols in a cross-over and randomized manner: Living altitude (PIO2 = 111.9 ± 0.6 vs. 111.6 ± 0.6 mmHg in NH and HH, respectively); training “natural” altitude (~1000–1100 m) and training loads were precisely matched between both LHTL protocols. Plasma levels of oxidative stress [advanced oxidation protein products (AOPP) and nitrotyrosine] and antioxidant markers [ferric-reducing antioxidant power (FRAP), superoxide dismutase (SOD) and catalase], NO metabolism end-products (NOx) and uric acid (UA) were determined before (Pre) and after (Post) the LHTL. Cumulative hypoxic exposure was lower during the NH (229 ± 6 hrs.) compared to the HH (310 ± 4 hrs.; P<0.01) protocol. Following the LHTL, the concentration of AOPP decreased (-27%; P<0.01) and nitrotyrosine increased (+67%; P<0.05) in HH only. FRAP was decreased (-27%; P<0.05) after the NH while was SOD and UA were only increased following the HH (SOD: +54%; P<0.01 and UA: +15%; P<0.01). Catalase activity was increased in the NH only (+20%; P<0.05). These data suggest that 18-days of LHTL performed in either NH or HH differentially affect oxidative status of athletes. Higher oxidative stress levels following the HH LHTL might be explained by the higher overall hypoxic dose and different physiological responses between the NH and HH.The study was funded by grants from the Ministère des Sports, de la Jeunesse, de l’Education Populaire et de la Vie Associative (MSJEPVA; France; to L.S. and G.P.M.), Institut National du Sport, de l’Expertise et de la Performance (INSEP; France; to L.S. and G.P.M.) and Institut Universitaire de France (IUF; France; to V.P.)

Transcriptomic biomarkers of altered erythropoiesis to detect autologous blood transfusion.

Autologous blood transfusion is a powerful means of improving performance and remains one of the most challenging methods to detect. Recent investigations have identified 3 candidate reticulocytes genes whose expression was significantly influenced by blood transfusion. Using quantitative reverse transcription polymerase chain reaction as an alternative quantitative method, the present study supports that delta-aminolevulinate synthase 2 (ALAS2), carbonic anhydrase (CA1), and solute carrier family 4 member 1 (SLC4A1) genes are down-regulated post-transfusion. The expression of these genes exhibited stronger correlation with immature reticulocyte fraction than with reticulocytes percentage. Moreover, the repression of reticulocytes' gene expression was more pronounced than the diminution of immature reticulocyte fraction and reticulocyte percentage following blood transfusion. It suggests that the 3 candidate genes are reliable predictors of bone marrow's response to blood transfusion and that they represent potential biomarkers for the detection of this method prohibited in sports

Similar Hemoglobin Mass Response in Hypobaric and Normobaric Hypoxia in Athletes

Purpose: To compare hemoglobin mass (Hbmass) changes during an 18-day live high-train low (LHTL) altitude training camp in normobaric hypoxia (NH) and hypobaric hypoxia (HH). Methods: Twenty-eight well-trained male triathletes were split into three groups (NH: n = 10, HH: n = 11, control (CON): n = 7) and participated in an 18-day LHTL camp. NH and HH slept at 2250 m while CON slept and all groups trained at altitudes 0.08) and remained unchanged in CON (+0.2%, P = 0.89). Conclusion: HH and NH evoked similar Hbmass increases for the same hypoxic dose and after 18-day LHTL. The wide variability in individual Hbmass responses in HH and NH emphasize the importance of individual Hbmass evaluation of altitude training.This study was financially supported by the Federal Office of Sport (FOSPO; Switzerland) and by the Ministère des Sports, de la Jeunesse, de l’Education Populaire et de la Vie Associative (MSJEPVA)/Institut National du Sport, de l’Expertise et de la Performance (INSEP, France)