The distribution of pace adopted by cyclists during a cross-country mountain bike World Championships.

The purpose of this study was to examine the distribution of pace self-selected by cyclists of varying ability, biological age and sex performing in a mountain bike World Championship event. Data were collected on cyclists performing in the Elite Male (ELITEmale; n = 75), Elite Female (ELITEfemale; n = 50), Under 23 Male (U23male; n = 62), Under 23 Female (U23female; n = 34), Junior Male (JNRmale; n = 71) and Junior Female (JNRfemale; n = 30) categories of the 2009 UCI Cross-Country Mountain Bike World Championships. Split times were recorded for the top, middle and bottom 20% of all finishers of each category. Timing splits were positioned to separate the course into technical and non-technical, uphill, downhill and rolling/flat sections. Compared with bottom performers, top performers in all male categories (ELITEmale, U23male, JNRmale) maintained a more even pace over the event as evidenced by a significantly lower standard deviation and range in average lap speed. Top performers, males, and ELITEmale athletes spent a lower percentage of overall race time on technical uphill sections of the course, compared with middle and bottom placed finishers, females, and JNRmale athletes, respectively. Better male performers adopt a more even distribution of pace throughout cross-country mountain events. Performance of lower placed finishers, females and JNRmale athletes may be improved by enhancing technical uphill cycling ability.

The contribution of haemoglobin mass to increases in cycling performance induced by simulated LHTL.

We sought to determine whether improved cycling performance following 'Live High-Train Low' (LHTL) occurs if increases in haemoglobin mass (Hb(mass)) are prevented via periodic phlebotomy during hypoxic exposure. Eleven, highly trained, female cyclists completed 26 nights of simulated LHTL (16 h day(-1), 3000 m). Hb(mass) was determined in quadruplicate before LHTL and in duplicate weekly thereafter. After 14 nights, cyclists were pair-matched, based on their Hb(mass) response (ΔHb(mass)) from baseline, to form a response group (Response, n = 5) in which Hb(mass) was free to adapt, and a Clamp group (Clamp, n = 6) in which ΔHb(mass) was negated via weekly phlebotomy. All cyclists were blinded to the blood volume removed. Cycling performance was assessed in duplicate before and after LHTL using a maximal 4-min effort (MMP(4min)) followed by a ride time to exhaustion test at peak power output (T (lim)). VO(2peak) was established during the MMP(4min). Following LHTL, Hb(mass) increased in Response (mean ± SD, 5.5 ± 2.9%). Due to repeated phlebotomy, there was no ΔHb(mass) in Clamp (-0.4 ± 0.6%). VO(2peak) increased in Response (3.5 ± 2.3%) but not in Clamp (0.3 ± 2.6%). MMP(4min) improved in both the groups (Response 4.5 ± 1.1%, Clamp 3.6 ± 1.4%) and was not different between groups (p = 0.58). T (lim) increased only in Response, with Clamp substantially worse than Response (-37.6%; 90% CL -58.9 to -5.0, p = 0.07). Our novel findings, showing an ~4% increase in MMP(4min) despite blocking an ~5% increase in Hb(mass), suggest that accelerated erythropoiesis is not the sole mechanism by which LHTL improves performance. However, increases in Hb(mass) appear to influence the aerobic contribution to high-intensity exercise which may be important for subsequent high-intensity efforts.

Carbon monoxide uptake kinetics of arterial, venous and capillary blood during CO rebreathing.

The uptake and distribution of CO throughout the circulatory system during two different methods of CO rebreathing (2 min 'Schmidt' and 40 min 'Burge' methods) were determined in nine healthy volunteers. Specifically, the impact of (i) differences in circulatory mixing time (t(mix)), (ii) CO diffusion to myoglobin (Mb) and (iii) CO wash-out was assessed on calculated haemoglobin mass (Hb(mass)). Arterial (a), muscle venous (vm) and capillary samples (c) were obtained simultaneously at 0, 1, 2, 3.5, 5, 7.5, 10, 12.5, 15, 20, 30 and 40 min for determination of carboxyhaemoglobin (HbCO). Carbon monoxide wash-out was measured from expired air following rebreathing. The rate of CO diffusion to Mb was calculated using the change in HbCO after t(mix), and the rate of CO wash-out. In both methods, HbCOa and HbCOc followed a near-identical time course, peaking within the first 2 min and decreasing thereafter. The HbCOvm increased slowly and was significantly lower at 1, 2 and 3.5 min in both methods (P < 0.01). The HbCOa peaked significantly higher in the Schmidt method (P = 0.03). Circulatory mixing had occurred by 10 min in most but not all subjects. The rate of CO wash-out was 0.25 ± 0.13 ml min⁻¹ in the Schmidt and 0.25 ± 0.16 ml min⁻¹ in the Burge method. The rate of CO diffusion to Mb was 0.22 ± 0.11 and 0.16 ± 0.13 ml min⁻¹ (P = 0.63) in Schmidt and Burge methods, respectively. Inhalation of a CO bolus during the Schmidt method results in faster HbCOa uptake but does not greatly shorten t(mix) or influence rates of CO wash-out and flux to Mb. The calculated Hb(mass) depends substantially on the plateau level of HbCO; therefore, it is paramount to ensure HbCO is mixed completely prior to blood sampling, as well as accounting for potential within-subject alterations of CO exhalation and CO flux to Mb.

Seasonal variation of haemoglobin mass in internationally competitive female road cyclists.

In order to quantify the seasonal variability of haemoglobin mass (Hb(mass)) in cyclists during a competitive season, and investigate whether variability is associated with changes in training load or performance, Hb(mass) was measured in 10 internationally competitive female road cyclists approximately once per month for 2-10 months via CO-rebreathing. Power meters were used to quantify daily load (Training Stress Scores) during training and racing, from which cumulative training load units for 7, 14, 28 and 42 day were calculated. Maximal mean power (MMP) for 1, 4, 10 and 25 min, performed during training or racing was used as a surrogate for performance. The relationship between changes in training load (%DeltaTraining) and changes in Hb(mass) (%DeltaHb(mass)), and between %DeltaHb(mass) and changes in MMP (%DeltaMMP) was established via regression analysis. Individual coefficients of variation (CV) in Hb(mass) ranged from 2.0 to 4.4%. The weighted mean CV in Hb(mass) was 3.3% (90% Confidence Limits: 2.9-3.8%) or 23 g over the average 6.6 +/- 2.3 month monitoring period. The effect of %DeltaTraining on %DeltaHb(mass) was small for 7 and 14 day (r = 0.22 and 0.29), moderate for 42 day (r = 0.35) and large for 28 day (r = 0.56). The regression slope was greatest for 42 day, with a 10% change in training associated with a approximately 1% change in Hb(mass). The relationship between %DeltaHb(mass) and %DeltaMMP was approximately 0.5:1 for MMP(1min),(10 min) and (25 min) and approximately 1:1 for MMP(4 min), respectively. Hb(mass) varies by approximately 3% in female cyclists during a competitive season. Some of the variation may be related to oscillations in chronic training load.

Stability of hemoglobin mass during a 6-day UCI ProTour cycling race.

OBJECTIVE: Blood doping in endurance sport is a growing problem. The purpose of this study was to determine the reliability of total hemoglobin mass (Hb(mass)) measurement in the field and to establish the variability of Hb(mass) during a cycling race, to assess its viability as an additional antidoping detection parameter. DESIGN: Control-matched longitudinal study. SETTING: International Cycling Union's (UCI) ProTour stage race. PARTICIPANTS: Six professional cyclists and 5 recreationally active controls. INTERVENTIONS: Seventy-two Hb(mass) tests using the optimized carbon monoxide rebreathing method were performed over 7 consecutive days, before and throughout the tour. Fasted venous blood was obtained for measurement of hematocrit (Hct) and hemoglobin concentration [Hb] in the morning before stages 1, 3, and 6 (D1, D3, and D6). MAIN OUTCOME MEASURES: Reliability of Hb(mass) measurement was established using typical error calculated from 2 baseline measures. Individual change scores and coefficients of variation were used to assess stability during racing. RESULTS: Typical error for Hb(mass) was 1.3% [95% confidence limits (CL): 0.9%, 2.5%]. Calculated 95% and 99.99% CL for percent change in Hb(mass) were +/-3.6% and +/-7.2%, respectively. Mean Hb(mass) remained within +/-1.9% of baseline in cyclists and +/-0.5% in controls. In all cases, individual change scores for both cyclists and controls fell within the 95% CL. There was a decrease in Hct (8.1% +/- 2.8%) and [Hb] (9.7% +/- 3.2%) throughout the tour in cyclists but not in controls. CONCLUSIONS: We demonstrate that Hb(mass) can be measured reliably via CO-rebreathing during a cycling tour. Unlike [Hb] and Hct, Hb(mass) remains stable over 6 days of racing in professional cyclists and may have potential in an antidoping context.

High altitude, prolonged exercise, and the athlete biological passport.

The Athlete Biological Passport (ABP) detects blood doping in athletes through longitudinal monitoring of erythropoietic markers. Mathematical algorithms are used to define individual reference ranges for these markers for each athlete. It is unclear if altitude and exercise can affect the variables included in these calculations in a way that the changes might be mistaken for blood manipulation. The aim of this study was to investigate the influence of the simultaneous strenuous exercise and low to high altitude exposure on the calculation algorithms of the ABP. 14 sea level (SL) and 11 altitude native (ALT) highly trained athletes participated in a 14-day cycling stage race taking place at an average altitude of 2496 m above sea level (min. 1014 m, max. 4120 m), race distances ranged between 96 and 227 km per day. ABP blood measures were taken on days -1,3,6,10,14 (SL) and -1,9,15 (ALT) of the race. Four results from three samples of two different SL athletes exceeded the individual limits at the 99% specificity threshold and one value at 99.9%. In ALT, three results from three samples of three different athletes were beyond the individual limits at 99%, one at 99.9%. The variations could be explained by the expected physiological reaction to exercise and altitude. In summary, the abnormalities observed in the haematological ABP´s of well-trained athletes during extensive exercise at altitude are limited and in line with expected physiological changes.

Lower running performance and exacerbated fatigue in soccer played at 1600 m.

PURPOSE: This study investigated the decrement in running performance of elite soccer players competing at low altitude and time course for abatement of these decrements. METHODS: Twenty elite youth soccer players had their activity profile, in a sea-level (SL) and 2 altitude (Alt, 1600 m, d 4, and d 6) matches, measured with a global positioning system. Measures expressed in meters per minute of match time were total distance, low- and high-velocity running (LoVR, 0.01-4.16 m/s; HiVR, 4.17-10.0 m/s), and frequency of maximal accelerations (>2.78 m/s2). The peak and subsequent stanza for each measure were identified and a transient fatigue index calculated. Mean heart rate (HR) during the final minute of a submaximal running task (5 min, 11 km/h) was recorded at SL and for 10 d at Alt. Differences were determined between SL and Alt using percentage change and effect-size (ES) statistic with 90% confidence intervals. RESULTS: Mean HR almost certainly increased on d 1 (5.4%, ES 1.01 ± 0.35) and remained probably elevated on both d 2 (ES 0.42 ± 0.31) and d3 (ES 0.30 ± 0.25), returning to baseline at d 5. Total distance was almost certainly lower than SL (ES -0.76 ± 0.37) at d 4 and remained probably reduced on d 6 (ES -0.42 ± 0.36). HiVR probably decreased at d 4 vs SL (-0.47 ± 0.59), with no clear effect of altitude at d 6 (-0.08 ± 0.41). Transient fatigue in matches was evident at SL and Alt, with a possibly greater decrement at Alt. CONCLUSION: Despite some physiological adaptation, match running performance of youth soccer players is compromised for at least 6 d at low altitude.

Intravenous iron supplementation in distance runners with low or suboptimal ferritin.

PURPOSE: Iron deficiency is prevalent in distance runners and may impair endurance performance. The current practice of oral supplementation is slow and often not well tolerated. The aim of this study was to assess the efficacy of intravenous (IV) iron supplementation (ferric carboxymaltose) compared with oral supplementation (ferrous sulfate) on iron status, hemoglobin mass (Hbmass), and physiological indices of running performance in distance runners. METHODS: Twenty-seven highly trained distance runners with low (LOW) (ferritin <35 µg·L(-1) and transferrin saturation <20%, or ferritin <15 µg·L(-1)) or suboptimal (SUB) iron status (ferritin <65 µg·L(-1)) were supplemented with either IV iron (Ferinject®) or oral (ORAL) supplements (Ferrogradumet) for 6 wk. Iron status and Hbmass were assessed before supplementation and at 1, 2, 4, 6, and 8 wk in the four groups (IV LOW, IV SUB, ORAL LOW, and ORAL SUB). In addition, athletes completed a treadmill running test for running economy, lactate threshold, and V˙O2max before and after supplementation. RESULTS: Both forms of supplementation substantially increased ferritin levels in all four groups. IV supplementation resulted in higher ferritin in both IV groups compared with both ORAL groups from week 1 onward. Hemoglobin concentration did not change substantially in any group. Hbmass increased in IV LOW (mean = +4.9%, 90% confidence interval [CI] = 1.1%-8.9%) and was accompanied by an increase in V˙O2max (mean = +3.3%, 90% CI = 0.4%-6.3%) and run time to exhaustion (mean = +9.3%, 90% CI = 0.9%-18.3%. CONCLUSIONS: IV supplementation can effectively increase iron stores in iron-deficient runners within 6 wk and, if Hbmass is compromised, may enhance endurance capacity by facilitating erythropoiesis. Hbmass appears a more sensitive tool for measuring changes in whole body hemoglobin than hemoglobin concentration and may be useful in the diagnosis and follow-up for iron deficiency.

Short-term hematological effects upon completion of a four-week simulated altitude camp.

Hemoglobin mass (tHb) is considered to be a main factor for sea-level performance after "live high-train low" (LHTL) altitude training, but little research has focused on the persistence of tHb following cessation of altitude exposure. The aim of the case study was to investigate short-term effects of various hematological measures including tHb upon completion of a simulated altitude camp. Five female cyclists spent 26 nights at simulated altitude (LHTL, 16.6 ± 0.4 h/d, 3000 m in an altitude house) where tHb was measured at baseline, at cessation of the camp, and 9 d thereafter. Venous blood measures (hemoglobin concentration, hematocrit, %reticulocytes, serum erythropoietin, ferritin, lactate dehydrogenase, and haptoglobin) were determined at baseline; on day 21 during LHTL; and at days 2, 5, and 9 after LHTL. Hemoglobin mass increased by 5.5% (90% confidence limits [CL] 2.5 to 8.5%, very likely) after the LHTL training camp. At day 9 after simulated LHTL, tHb decreased by 3.0% (90%CL -5.1 to -1.0%, likely). There was a substantial decrease in serum EPO (-34%, 90%CL -50 to -12%) at 2 d after return to sea level and a rise in ferritin (23%, 90%CL 3 to 46%) coupled with a decrease in %reticulocytes (-23%, 90%CL -34 to -9%) between day 5 and 9 after LHTL. Our findings show that following a hypoxic intervention with a beneficial tHb outcome, there may be a high probability of a rapid tHb decrease upon return to normoxic conditions. This highlights a rapid component in red-cell control and may have implications for the appropriate timing of altitude training in relation to competition.

Haemoglobin mass in an anaemic female endurance runner before and after iron supplementation.

Haemoglobin mass in a female endurance athlete was measured via carbon monoxide rebreathing upon diagnosis of iron-deficiency anemia (haemoglobin concentration = 8.8 g/dL, ferritin = 9.9 ng/mL) and regularly during treatment thereafter. Haemoglobin mass increased by 49% in the 2 wk following an intramuscular iron injection and continued to increase with oral iron supplementation for 15 wk. The presented case illustrates that haemoglobin mass is readily responsive to iron supplementation in a severely iron-deficient anemic athlete and that changes can be tracked efficiently using the CO-rebreathing method.

Standardising analysis of carbon monoxide rebreathing for application in anti-doping.

Determination of total haemoglobin mass (Hbmass) via carbon monoxide (CO) depends critically on repeatable measurement of percent carboxyhaemoglobin (%HbCO) in blood with a hemoximeter. The main aim of this study was to determine, for an OSM3 hemoximeter, the number of replicate measures as well as the theoretical change in percent carboxyhaemoglobin required to yield a random error of analysis (Analyser Error) of ≤1%. Before and after inhalation of CO, nine participants provided a total of 576 blood samples that were each analysed five times for percent carboxyhaemoglobin on one of three OSM3 hemoximeters; with approximately one-third of blood samples analysed on each OSM3. The Analyser Error was calculated for the first two (duplicate), first three (triplicate) and first four (quadruplicate) measures on each OSM3, as well as for all five measures (quintuplicates). Two methods of CO-rebreathing, a 2-min and 10-min procedure, were evaluated for Analyser Error. For duplicate analyses of blood, the Analyser Error for the 2-min method was 3.7, 4.0 and 5.0% for the three OSM3s when the percent carboxyhaemoglobin increased by two above resting values. With quintuplicate analyses of blood, the corresponding errors reduced to .8, .9 and 1.0% for the 2-min method when the percent carboxyhaemoglobin increased by 5.5 above resting values. In summary, to minimise the Analyser Error to ∼≤1% on an OSM3 hemoximeter, researchers should make ≥5 replicates of percent carboxyhaemoglobin and the volume of CO administered should be sufficient increase percent carboxyhaemoglobin by ≥5.5 above baseline levels.

Novel precooling strategy enhances time trial cycling in the heat.

PURPOSE: To develop and investigate the efficacy of a new precooling strategy combining external and internal techniques on the performance of a cycling time trial (TT) in a hot and humid environment. METHODS: Eleven well-trained male cyclists undertook three trials of a laboratory-based cycling TT simulating the course characteristics of the Beijing Olympic Games event in a controlled hot and humid environment (32°C-35°C at 50%-60% relative humidity). The trials, separated by 3-7 d, were undertaken in a randomized crossover design and consisted of the following: 1) CON-no treatment apart from the ad libitum consumption of cold water (4°C), 2) STD COOL-whole-body immersion in cold (10°C) water for 10 min followed by wearing a cooling jacket, or 3) NEW COOL-combination of consumption of 14 g of ice slurry ("slushie") per kilogram body mass made from a commercial sports drink while applying iced towels. RESULTS: There was an observable effect on rectal temperature (T(rec)) before the commencement of the TT after both precooling techniques (STD COOL < NEW COOL < CON, P < 0.05), but pacing of the TT resulted in similar T(rec), HR, and RPE throughout the cycling protocol in all trials. NEW COOL was associated with a 3.0% increase in power (approximately 8 W) and a 1.3% improvement in performance time (approximately 1:06 min) compared with the CON trial, with the true likely effects ranging from a trivial to a large benefit. The effect of the STD COOL trial compared with the CON trial was "unclear." CONCLUSIONS: This new precooling strategy represents a practical and effective technique that could be used by athletes in preparation for endurance events undertaken in hot and humid conditions.