Increase In Hbmass Research Articles

Individual variations in pre-altitude hemoglobin mass influence hemoglobin mass responses to repeated altitude sojourns.

Previous studies have shown variable within-subject hemoglobin mass (Hbmass ) responses to altitude training. We investigated whether Hbmass responses depend on individual variations in pre-altitude Hbmass during repeated altitude sojourns. Nine elite endurance athletes carried out 3-5 altitude sojourns over 17 ± 10months (mean ± 95% confidence interval), at an altitude of 1976 ± 62 m, for 21 ± 1 days, and a total hypoxic dose of 989 ± 46km·h, with Hbmass assessed before and after each sojourn (carbon monoxide rebreathing). The individual mean baseline was calculated as the mean of all pre-altitude Hbmass values for an athlete, and it was investigated whether the percent deviation from the individual mean baseline affected the altitude-induced Hbmass response. On average, Hbmass increased by 3.4 ± 1.1% (p < 0.001) from pre- to post-altitude. The intra-individual changes in Hbmass were highly inconsistent (coefficient of variation, CV: 88%), and we found no relationship between Hbmass changes in successive altitude sojourns (r=0.01; p=0.735). However, the percent increase in Hbmass was highly correlated with the pre-altitude Hbmass , expressed as the percent deviation from the individual mean baseline (y=-0.7x + 3.4; r=0.75; p < 0.001). Linear mixed-model analysis confirmed a -0.6 ± 0.2% smaller increase in Hbmass for each 1% higher pre-altitude Hbmass than the individual mean baseline (p < 0.001) after adjusting for the covariates hypoxic dose (p=0.032) and the relative Hbmass (g·kg-1 body weight; p=0.031). Individual variations in pre-altitude Hbmass significantly influence the athletes' Hbmass responses to repeated altitude sojourns, with a potentiated response after traveling to altitude with a low pre-altitude Hbmass .

Hemoglobin Mass and Blood Volume in Patients With Altitude-Related Polycythemia.

Patients with chronic mountain sickness (CMS) have a high hemoglobin concentration [Hb] due to increased hemoglobin mass (Hbmass) and possibly reduced plasma volume (PV). The values of Hbmass, PV and blood volume (BV) have been described differently, and the relationships between [Hb] and Hbmass or PV are poorly understood. This study obtained representative Hbmass, PV and BV data from healthy, high-altitude residents and CMS patients and quantified the dependency of [Hb] on Hbmass and PV. Methods: Eighty-seven subjects born at high altitude (∼3,900 m) were enrolled. Thirty-four had CMS (CMS), 11 had polycythemia without CMS (intermediate, IM), 20 were healthy highlanders (HH), and 22 living near sea level (SL, 420 m) served as the sea level (SL) control group. Hbmass, PV and BV were determined using a CO-rebreathing method modified for assessing polycythemia patients. Furthermore, [Hb], hematocrit (Hct), plasma erythropoietin concentration [EPO] and blood gas and acid–base status were determined. Results: In the HH group, Hbmass was 27% higher (940 ± 105 g) than in the SL group (740 ± 112 g) and 72% (1,617 ± 265 g) lower than in the CMS group. The PV in the HH group was similar to that in the SL group (−6%) and 15% higher than that in the CMS group (p < 0.001). In the HH group, the BV (5,936 ± 673 ml) did not differ from that in the SL group and was 28% lower than in the CMS group (7,606 ± 1075 ml, p < 0.001). Log [EPO] was slightly increased in the CMS group relative to the HH group (p < 0.01). All values in the IM group were between those in the HH and CMS groups. Hbmass and BV were positively correlated, and PV was negatively correlated with peripheral O2 saturation. Increased Hbmass and decreased PV contributed approximately 65 and 35%, respectively, to the difference in [Hb] between the HH (17.1 ± 0.8 g/dl) and CMS (22.1 ± 1.0 g/dl) groups. Conclusions: In CMS patients, the decrease in PV only partially compensated for the substantial increase in Hbmass, but it did not prevent an increase in BV; the decrease in PV contributed to an excessively high [Hb].

Heat Training Efficiently Increases and Maintains Hemoglobin Mass and Temperate Endurance Performance in Elite Cyclists.

To test whether heat training performed as 5 × 50-min sessions per week for 5 wk in a heat chamber (CHAMBER) or while wearing a heat suit (SUIT), in temperate conditions, increases hemoglobin mass (Hb mass ) and endurance performance in elite cyclists, compared with a control group (CON-1). Furthermore, after the 5-wk intervention, we tested whether three sessions per week for 3 wk with heat suit (SUIT main ) would maintain Hb mass elevated compared with athletes who returned to normal training (HEAT stop ) or who continued to be the control group (CON-2). During the initial 5 wk, SUIT and CHAMBER increased Hb mass (2.6% and 2.4%) to a greater extent than CON-1 (-0.7%; both P < 0.01). The power output at 4 mmol·L -1 blood lactate and 1-min power output ( Wmax ) improved more in SUIT (3.6% and 7.3%, respectively) than CON-1 (-0.6%, P < 0.05; 0.2%, P < 0.01), whereas this was not the case for CHAMBER (1.4%, P = 0.24; 3.4%, P = 0.29). However, when SUIT and CHAMBER were pooled this revealed a greater improvement in a performance index (composed of power output at 4 mmol·L -1 blood lactate, Wmax , and 15-min power output) than CON-1 (4.9% ± 3.2% vs 1.7% ± 1.1%, respectively; P < 0.05). During the 3-wk maintenance period, SUIT main induced a larger increase in Hb mass than HEAT stop (3.3% vs 0.8%; P < 0.05), which was not different from the control (CON-2; 1.6%; P = 0.19), with no differences between HEAT stop and CON-2 ( P = 0.52). Both SUIT and CHAMBER can increase Hb mass , and pooling SUIT and CHAMBER demonstrates that heat training can increase performance. Furthermore, compared with cessation of heat training, a sustained increase in Hb mass was observed during a subsequent 3-wk maintenance period, although the number of weekly heat training sessions was reduced to 3.

Heat suit training increases hemoglobin mass in elite cross-country skiers.

PurposeThe primary purpose was to test the effect of heat suit training on hemoglobin mass (Hbmass) in elite cross‐country (XC) skiers.MethodsTwenty‐five male XC‐skiers were divided into a group that added 5 × 50 min weekly heat suit training sessions to their regular training (HEAT; n = 13, 23 ± 5 years, 73.9 ± 5.2 kg, 180 ± 6 cm, 76.8 ± 4.6 ml·min−1·kg−1) or to a control group matched for training volume and intensity distribution (CON; n = 12, 23 ± 4 years, 78.4 ± 5.8 kg, 184 ± 4 cm, 75.2 ± 3.4 ml·min−1·kg−1) during the five‐week intervention period. Hbmass, endurance performance and factors determining endurance performance were assessed before and after the intervention.ResultsHEAT led to 30 g greater Hbmass (95% CI: [8.5, 51.7], p = 0.009) and 157 ml greater red blood cell volume ([29, 285], p = 0.018) post‐intervention, compared to CON when adjusted for baseline values. In contrast, no group differences were observed for changes in work economy, running velocity, and fractional utilization of maximal oxygen uptake (V̇O2max) at 4 mmol·L−1 blood lactate, V̇O2max or 15‐min running distance performance trial during the intervention.ConclusionHEAT induced a larger increase in Hbmass and red blood cell volume after five weeks with five weekly heat suit training sessions than CON, but with no detectable group differences on physiological determinants of endurance performance or actual endurance performance in elite CX skiers.

Quantification of testosterone-dependent erythropoiesis during male puberty.

What is the central question of this study? To what extent does testosterone influence haemoglobin formation during male puberty? What is the main finding and its importance? In boys, testosterone might be responsible for about 65% of the increase in haemoglobin mass during puberty. The underlying mechanisms are assumed to be twofold: (i) indirectly, mediated by the increase in lean body mass, and (ii) directly by immediate testosterone effects on erythropoiesis. Thereby, an increase in testosterone of 1ng/ml is associated with an increase in haemoglobin mass of ∼65g. These processes are likely to determine endurance performance in adulthood. The amount of haemoglobin during puberty is related to endurance performance in adulthood. During male puberty, testosterone stimulates erythropoiesis and could therefore be used as a marker for later endurance performance. This cross-sectional study aimed to determine the relationship between serum testosterone concentration and haemoglobin mass (Hbmass) in both male and female children and adolescents and to evaluate the possible influences of altitude and training. Three-hundred and thirteen differentially trained boys and girls aged from 9 to 18years and living at altitudes of 1000 and 2600m above sea level entered the study. The stage of sexual maturation was determined according to the classification of Tanner. Testosterone was measured by ELISA. Hbmass was determined by CO-rebreathing. Haemoglobin concentration did not change during maturation in girls and was 11% higher during puberty in boys, while Hbmass was elevated by 33% in Tanner stage V compared to stage II in girls (498 ± 77 vs. 373 ± 88g) and by 95% in boys (832 ± 143 vs. 428 ± 95g). This difference can most likely be attributed to indirect testosterone influences through an increase in lean body mass (LBM) and to direct testosterone effects on erythropoiesis, which increase the Hbmass by ∼65g per 1ng/ml. Altitude and training statuses were not associated with testosterone, but with an increase in Hbmass (altitude by 1.1g/kg LBM, training by 0.8g/kg LBM). Changes in Hbmass are closely related to testosterone levels during male puberty. Further studies will show whether testosterone and Hbmass during childhood and adolescence can be used as diagnostic tools for endurance talents.

Impact of baseline serum ferritin and supplemental iron on altitude-induced hemoglobin mass response in elite athletes.

The present study explored the impact of pre-altitude serum (s)-ferritin and iron supplementation on changes in hemoglobin mass (ΔHbmass) following altitude training. Measures of Hbmass and s-ferritin from 107 altitude sojourns (9-28days at 1800-2500m) with world-class endurance athletes (males n=41, females n=25) were analyzed together with iron supplementation and self-reported illness. Altitude sojourns with a hypoxic dose [median (range)] of 1169 (912) km·h increased Hbmass (mean±SD) 36±38g (3.7±3.7%, p<0.001) and decreased s-ferritin -11 (190) µg·L-1 (p=0.001). Iron supplements [27 (191) mg·day-1 ] were used at 45 sojourns (42%), while only 11 sojourns (10%) were commenced with s-ferritin <35µg/L. Hbmass increased by 4.6±3.7%, 3.4±3.3%, 4.2±4.3%, and 2.9±3.4% with pre-altitude s-ferritin ≤35µg·L-1 , 36-50µg·L-1 , 51-100µg·L-1 , and >100µg·L-1 , respectively, with no group difference (p=0.400). Hbmass increased by 4.1±3.9%, 3.0±3.0% and 3.7±4.7% without, ≤50mg·day-1 or >50mg·day-1 supplemental iron, respectively (p=0.399). Linear mixed model analysis revealed no interaction between pre-altitude s-ferritin and iron supplementation on ΔHbmass (p=0.906). However, each 100km·h increase in hypoxic dose augmented ΔHbmass by an additional 0.4% (95% CI: 0.1-0.7%; p=0.012), while each 1g·kg-1 higher pre-altitude Hbmass reduced ΔHbmass by -1% (-1.6 to -0.5; p<0.001), and illness lowered ΔHbmass by -5.7% (-8.3 to -3.1%; p<0.001). In conclusion, pre-altitude s-ferritin or iron supplementation were not related to the altitude-induced increase in Hbmass (3.7%) in world-class endurance athletes with clinically normal iron stores.

Five weeks of heat training increases haemoglobin mass in elite cyclists.

What is the central question of this study? Do haemoglobin mass and red blood cell volume increase in elite cyclists training in a hot environment compared to a control group training at normal temperature? What is the main finding and its importance? Fiveweeks of heat training increases haemoglobin mass in elite cyclists. There are small to intermediate effect sizes for exercise parameters favouring heat training. In this study we tested the hypothesis that performing 1h of regular light exercise in a heat chamber (HEAT; 37.8±0.5°C; 65.4±1.8% humidity) 5timesweek-1 for a total of 5weeks increases haemoglobin mass (Hbmass ) and exercise performance in elite cyclists ( =76.2±7.6mlmin-1 kg-1 ). Twenty-three male volunteers were assigned to HEAT (n=11) or CON (n=12; 15.5±0.1°C; 25.1±0.0% humidity) training groups. Hbmass was determined before and after the intervention period in conjunction with an extensive exercise test protocol (conducted at 16-19°C). HEAT increased (P<0.05) Hbmass by 42g from 893±78 to 935±108g whereas Hbmass remained unchanged (+6g) in CON. Furthermore, statistical analysis revealed a time-group interaction (P<0.05). The greater increase in Hbmass in HEAT, however, did not manifest in a greater increase in (225±274mlmin-1 in HEAT and 161±202mlmin-1 in CON). While HEAT reduced (P<0.05) lactate levels during some of the submaximal exercise tests, there was no statistical difference between other performance parameters. There were, however, small to intermediate effect sizes favouring HEAT for lactate threshold power output (2.8±3.9 vs. -0.4±5.1% change, effect size (ES)=0.34), gross economy in the fatigued state (0.19±0.42 vs. -0.12±0.49%-point change, ES=0.52) and 15min mean power (6.9±8.4vs. 3.4±5.1% increase, ES=0.22). This study demonstrates an increase in Hbmass and small to intermediate effect sizes on exercise variables in elite cyclists following a 5-week heat training intervention.

Chronic Exposure to Low-Dose Carbon Monoxide Alters Hemoglobin Mass and V˙O2max.

This study aimed to determine the effect of chronic low-dose CO application on hemoglobin mass (Hbmass) and V˙O2max. For 3 wk, 11 healthy and moderately trained male subjects inhaled a CO bolus five times per day to increase their HbCO concentration by ~5%. Another 11 subjects received a placebo. Hbmass, serum erythropoietin concentration, ferritin, and basic hematological parameters were determined before and weekly during and until 3 wk after the CO inhalation period. V˙O2max tests on a cycle ergometer were performed before and after the CO administration period. In the CO group, Hbmass increased from 919 ± 69 to 962 ± 78 g in week 3 (P < 0.001) and was maintained for the following 3 wk. Reticulocytes (%) and immature reticulocyte fraction significantly increased after 1 wk. Serum erythropoietin concentration tended to increase after 1 wk (P = 0.07) and was suppressed in the postperiod (P < 0.01). Ferritin decreased during the inhalation period (from 106 ± 37 to 72 ± 37 ng·mL, P < 0.001). V˙O2max tended to increase from 4230 ± 280 to 4350 ± 350 mL·min (P < 0.1) immediately after the inhalation period and showed a significant relationship to the change in Hbmass (y = 4.1x - 73.4, r = 0.70, P < 0.001). Chronic continuous exposure to low-dose CO enhances erythropoietic processes resulting in a 4.8% increase in Hbmass. The individual changes in Hbmass were correlated to the corresponding changes in V˙O2max. Examination of ethical and safety concerns is warranted before the implementation of low-dose CO inhalation in the clinical/athletic setting as a tool for modifying Hbmass.

Hematological Adaptations to Prolonged Heat Acclimation in Endurance-Trained Males.

Heat acclimation is associated with plasma volume (PV) expansion that occurs within the first week of exposure. However, prolonged effects on hemoglobin mass (Hbmass) are unclear as intervention periods in previous studies have not allowed sufficient time for erythropoiesis to manifest. Therefore, Hbmass, intravascular volumes, and blood volume (BV)-regulating hormones were assessed with 5½ weeks of exercise-heat acclimation (HEAT) or matched training in cold conditions (CON) in 21 male cyclists [(mean ± SD) age: 38 ± 9 years, body weight: 80.4 ± 7.9 kg, VO2peak: 59.1 ± 5.2 ml/min/kg]. HEAT (n = 12) consisted of 1 h cycling at 60% VO2peak in 40°C for 5 days/week in addition to regular training, whereas CON (n = 9) trained exclusively in cold conditions (<15°C). Before and after the intervention, Hbmass and intravascular volumes were assessed by carbon monoxide rebreathing, while reticulocyte count and BV-regulating hormones were measured before, after 2 weeks and post intervention. Total training volume during the intervention was similar (p = 0.282) between HEAT (509 ± 173 min/week) and CON (576 ± 143 min/week). PV increased (p = 0.004) in both groups, by 303 ± 345 ml in HEAT and 188 ± 286 ml in CON. There was also a main effect of time (p = 0.038) for Hbmass with +34 ± 36 g in HEAT and +2 ± 33 g in CON and a tendency toward a higher increase in Hbmass in HEAT compared to CON (time × group interaction: p = 0.061). The Hbmass changes were weakly correlated to alterations in PV (r = 0.493, p = 0.023). Reticulocyte count and BV-regulating hormones remained unchanged for both groups. In conclusion, Hbmass was slightly increased following prolonged training in the heat and although the mechanistic link remains to be revealed, the increase could represent a compensatory response in erythropoiesis secondary to PV expansion.

Greater blood volume and Hb mass in obese women quantified by the carbon monoxide-rebreathing method affects interpretation of iron biomarkers and iron requirements

Background/objectiveIron deficiency (ID) is common in overweight and obese individuals (OW/OB) but the mechanism is uncertain. Greater blood volume (BV) in OW/OB may increase hemoglobin (Hb) mass and iron requirements, and confound iron biomarkers by hemodilution. Quantification of BV/PV changes in OW/OB is challenging and a formula to estimate BV/PV based on anthropometric indices would be valuable. In normal weight (NW) and OW/OB women, we aimed at: (1) measure BV and assess whether differences in BV affect concentrations and total circulating mass of Hb and iron biomarkers; (2) develop an algorithm describing BV in OW/OB.Subjects/methodsIn a cross-sectional study, we measured BV in NW, OW, and OB non-anemic women (n = 62) by using the carbon monoxide-rebreathing method, body composition by dual energy X-ray absorptiometry, and iron and inflammatory status.ResultsOW and OB women had 11 and 16% higher mean BV and PV compared to NW (P < 0.05), respectively. In OW/OB compared to NW, total circulating masses of IL-6, hepcidin, Hb, and sTfR were higher, while total mass of serum iron was lower (for all, P < 0.05). An equation including height, body mass and lean mass to estimate BV in all BMI groups (R2 = 0.76).ConclusionAn equation based on anthropometric indices provides a good estimate of increased BV in OW/OB women. In OW/OB women, there is an increase in Hb mass that likely increases iron requirements for erythropoiesis and circulating TfR mass. At the same time, higher hepcidin concentrations may lower serum iron mass. Both these mechanisms may increase risk for ID in OW/OB women.

Influence of Endurance Training During Childhood on Total Hemoglobin Mass

Elite endurance athletes are characterized by markedly increased hemoglobin mass (Hbmass). It has been hypothesized that this adaptation may occur as a response to training at a very young age. Therefore, the aim of this study was to monitor changes in Hbmass in children aged 8–14 years following systematic endurance training. In the first study, Hbmass, VO2max, and lean body mass (LBM) were measured in 17 endurance-trained children (13 boys and 4 girls; aged 9.7 ± 1.3 years; training history 1.5±1.8 years; training volume 3.5 ± 1.6 h) twice a year for up to 3.5 years. The same parameters were measured once in a control group of 18 age-matched untrained children. Hbmass and blood volume (BV) were measured using the optimized CO-rebreathing technique, VO2max by an incremental test on a treadmill, and LBM by skin-fold measurements. In the second pilot study, the same parameters were measured in 9 young soccer athletes (aged 7.8 ± 0.2 years), and results were assessed in relation to soccer performance 2.5 years later. The increase in mean Hbmass during the period of study was 50% which was closely related to changes in LBM (r = 0.959). A significant impact of endurance training on Hbmass was observed in athletes exercising more than 4 h/week [+25.4 g compared to the group with low training volume (<2 h/week)]. The greatest effects were related to LBM (11.4 g·kg−1 LBM) and overlapped with the effects of age. A strong relationship was present between absolute Hbmass and VO2max (r = 0.939), showing that an increase of 1 g hemoglobin increases VO2max by 3.6 ml·min−1. Study 2 showed a positive correlation between Hbmass and soccer performance 2.5 years later at age 10.3 ± 0.3 years (r = 0.627, p = 0.035). In conclusion, children with a weekly training volume of more than 4 h show a 7% higher Hbmass than untrained children. Although this training effect is significant and independent of changes in LBM, the major factor driving the increase in Hbmass is still LBM.

Individual hemoglobin mass response to normobaric and hypobaric "live high-train low": A one-year crossover study.

The purpose of this research was to compare individual hemoglobin mass (Hbmass) changes following a live high-train low (LHTL) altitude training camp under either normobaric hypoxia (NH) or hypobaric hypoxia (HH) conditions in endurance athletes. In a crossover design with a one-year washout, 15 male triathletes randomly performed two 18-day LHTL training camps in either HH or NH. All athletes slept at 2,250 meters and trained at altitudes <1,200 meters. Hbmass was measured in duplicate with the optimized carbon monoxide rebreathing method before (pre) and immediately after (post) each 18-day training camp. Hbmass increased similarly in HH (916-957 g, 4.5 ± 2.2%, P < 0.001) and in NH (918-953 g, 3.8 ± 2.6%, P < 0.001). Hbmass changes did not differ between HH and NH (P = 0.42). There was substantial interindividual variability among subjects to both interventions (i.e., individual responsiveness or the individual variation in the response to an intervention free of technical noise): 0.9% in HH and 1.7% in NH. However, a correlation between intraindividual ΔHbmass changes (%) in HH and in NH (r = 0.52, P = 0.048) was observed. HH and NH evoked similar mean Hbmass increases following LHTL. Among the mean Hbmass changes, there was a notable variation in individual Hbmass response that tended to be reproducible.NEW & NOTEWORTHY This is the first study to compare individual hemoglobin mass (Hbmass) response to normobaric and hypobaric live high-train low using a same-subject crossover design. The main findings indicate that hypobaric and normobaric hypoxia evoked a similar mean increase in Hbmass following 18 days of live high-train low. Notable variability and reproducibility in individual Hbmass responses between athletes was observed, indicating the importance of evaluating individual Hbmass response to altitude training.

Four-day Head-down Tilt Bed Rest as a Model for Studying Rapid Alterations in Hemoglobin Mass

Rapid decreases in hemoglobin mass (Hbmass) have been reported in healthy humans with spaceflight and following descent from high altitude. It has been proposed that a selective increase in the destruction of young red blood cells (RBCs) mediates these decreases but conclusive evidence demonstrating neocytolysis is lacking. Based on the proposed triggers and time course of adaptation during spaceflight, we hypothesized that 4 days of −6° head-down tilt bed rest (HDTBR) would cause a rapid decrease in Hbmass that would be associated with evidence of increased RBC destruction. PURPOSE: To examine changes in Hbmass before (PRE), 5 hours after (POST), and 5 days after (POST5) 4 days of HDTBR. METHODS: Seven healthy, recreationally active men (age: 21 ± 3 years, peak oxygen uptake: 50 ± 6 mL kg-1 min-1) completed 4 days of HDTBR. Hbmass was assessed using the optimized carbon monoxide rebreathing method. Markers of RBC production and destruction assessed included [erythropoietin] ([EPO]), [soluble transferrin receptor] ([sTfr]), reticulocyte count, [ferritin], [haptoglobin], and [bilirubin]. RESULTS: [EPO] decreased by 30 ± 33% from PRE to POST (p = 0.028). Contrary to our hypothesis, Hbmass was increased by 4.0 ± 4.3% from PRE to POST (p = 0.014) before decreasing to a level 3.6 ± 2.4% below PRE at POST5 (p = 0.027). From PRE to POST, [haptoglobin] increased 66 ± 73% (p = 0.013), [bilirubin] decreased 26 ± 34% (p = 0.054), [ferritin] increased 17 ± 17 % (p = 0.012), and reticulocyte count remained stable. From PRE to POST5, sTfr decreased 17 ± 5% (p = 0.018) but there were no significant alterations in [ferritin], [haptoglobin], [bilirubin] or reticulocyte count. CONCLUSION: Our findings suggest that 4-day HDTBR results in a transient increase in Hbmass that may be influenced by decreased RBC destruction. However, since the POST measurement occurred following re-ambulation, a potential role for other factors (i.e., spleen contraction) on the increase in Hbmass cannot be excluded. The decrease in Hbmass at POST5 appears to be mediated by decreased RBC production rather than increased RBC destruction. These findings highlight the need to re-examine the time course and mechanisms of Hbmass alterations with short-term spaceflight and simulated microgravity.

Haemoglobin mass alterations in healthy humans following four-day head-down tilt bed rest.

What is the central question of this study? Is haemoglobin mass (Hbmass) decreased following 4days of head-down tilt bed rest (HDTBR), and does increased red blood cell (RBC) destruction mediate this adaptation? What is the main finding and its importance? Haemoglobin mass was increased immediately following HDTBR, before decreasing below baseline 5days after return to normal living conditions. The transient increase in Hbmass might be the result of decreased RBC destruction, but it is also possible that spleen contraction after HDTBR contributed to this adaptation. Our data suggest that the decreased Hbmass 5days following HDTBR resulted from decreased RBC production, not increased RBC destruction. Rapid decreases in haemoglobin mass (Hbmass) have been reported in healthy humans following spaceflight and descent from high altitude. It has been proposed that a selective increase in the destruction of young red blood cells (RBCs) mediates these decreases, but conclusive evidence demonstrating neocytolysis in humans is lacking. Based on the proposed triggers and time course of adaptation during spaceflight, we hypothesized that Hbmass would be reduced after 4 days of -6deg head-down tilt bed rest (HDTBR) and that this would be associated with evidence for increased RBC destruction. We assessed Hbmass in seven healthy, recreationally active men before (PRE), 5h after (POST) and 5 days after (POST5) 4days of HDTBR. The concentration of erythropoietin decreased from 7.1±1.8 mIU ml(-1) at PRE to 5.2±2.8 mIU ml(-1) at POST (mean±SD; P=0.028). Contrary to our hypothesis, Hbmass was increased from 817±135g at PRE to 849±141g at POST (P=0.014) before decreasing below PRE to 789±139g at POST5 (P=0.027). From PRE to POST, the concentration of haptoglobin increased from 0.54±0.32 to 0.68±0.28gl(-1) (P=0.013) and the concentration of bilirubin decreased from 0.50±0.24 to 0.32±0.11mg dl(-1) (P=0.054), suggesting that decreased RBC destruction might have contributed to the increased Hbmass. However, it is possible that spleen contraction following HDTBR also played a role in the increase in Hbmass at POST, but as the transient increase in Hbmass was unexpected, we did not collect data that would provide direct evidence for or against spleen contraction. From PRE to POST5, the concentration of soluble transferrin receptor decreased from 20.7±3.9 to 17.1±3.3nmoll(-1) (P=0.018) but the concentrations of ferritin, haptoglobin and bilirubin were not significantly altered, suggesting that the decrease in Hbmass was mediated by decreased RBC production rather than increased RBC destruction. Peak oxygen uptake decreased by 0.31±0.16l min(-1) from PRE to POST (P=2×10(-4) ) but was not significantly altered at POST5 compared with PRE. Overall, these findings indicate that 4days of HDTBR does not increase RBC destruction and that re-examination of the time course and mechanisms of Hbmass alterations following short-term spaceflight and simulated microgravity is warranted.

Monitoring recovery from iron deficiency using total hemoglobin mass.

Using hemoglobin concentration ([Hb]) to diagnose borderline iron deficiency and monitor the progress of its treatment is difficult because of the confounding effects of plasma volume. Because hemoglobin mass (Hbmass) is not affected by plasma volume, it may be a more sensitive parameter. The aim of this study was to monitor Hbmass, iron storage, and maximal oxygen consumption (V˙O2max) during and after oral iron therapy in subjects with severe and moderate iron deficiency. Three groups of female recreational athletes were monitored for at least 22 wk, as follows: 1) severe iron deficiency group (SID) (n = 8; ferritin, ≤12 ng·mL), 2) moderate iron deficiency group (MID) (n = 14; ferritin, ≤25 ng·mL), and 3) control group (n = 8; ferritin, >25 ng·mL). Hbmass and iron status were determined before, during, and up to 12 wk after at least 10 wk of oral iron supplementation. In total, five V˙O2max tests were performed before, during, and after the supplementation period. Hbmass increased markedly in the SID group (15.6% ± 11.0%, P < 0.001) and slightly in the MID group (2.2% ± 3.7%, P < 0.05) by the end of the supplementation period and remained at this level for the following 12 wk. [Hb] and Hbmass were similarly affected, but Hbmass was more closely related to mean corpuscular volume and mean corpuscular hemoglobin than [Hb]. The SID group incorporated 534 ± 127 mg of iron into ferritin and hemoglobin, whereas the MID group incorporated 282 ± 68 mg of iron. V˙O2max increased only in the SID group by 0.20 ± 0.18 L·min (P < 0.05) and was closely related to Hbmass (P < 0.01). Hbmass is a sensitive tool for monitoring recovery from iron deficiency anemia and assessing the effectiveness of iron supplementation in individuals with severe or moderate iron deficiency.

Stage racing at altitude induces hemodilution despite an increase in hemoglobin mass.

Plasma volume (PV) can be modulated by altitude exposure (decrease) and periods of intense exercise (increase). Cycle racing at altitude combines both stimuli, although presently no data exist to document which is dominant. Hemoglobin mass (Hbmass), hemoglobin concentration ([Hb]), and percent reticulocytes (%Retics) of altitude (ALT; n = 9) and sea-level (SL; n = 9) residents were measured during a 14-day cycling race, held at 1,146-4120 m, as well as during a simulated tour near sea level (SIM; n = 12). Hbmass was assessed before and on days 9 and 14 of racing. Venous blood was collected on days 0, 3, 6, 10, and 14. PV was calculated from Hbmass and [Hb]. A repeated-measures ANOVA was used to assess the impact of racing at altitude over time, within and between groups. [Hb] decreased significantly in all groups over time (P < 0.0001) with decreases evident on the third day of racing. %Retics increased significantly in SL only (P < 0.0001), with SL values elevated at day 6 compared with prerace (P = 0.02), but were suppressed by the end of the race (P = 0.0002). Hbmass significantly increased in SL after 9 (P = 0.0001) and 14 (P = 0.008) days of racing and was lower at the end of the race than midrace (P = 0.018). PV increased in all groups (P < 0.0001). Multiday cycle racing at altitude induces hemodilution of a similar magnitude to that observed during SL racing and occurs in nonacclimatized SL residents, despite an altitude-induced increase in Hbmass. Osmotic regulatory mechanisms associated with intense exercise appear to supersede acute enhancement of oxygen delivery at altitude.

Adding heat to the live-high train-low altitude model: a practical insight from professional football

ObjectivesTo examine with a parallel group study design the performance and physiological responses to a 14-day off-season ‘live high-train low in the heat’ training camp in elite football players.MethodsSeventeen professional...

Year-to-year variability in haemoglobin mass response to two altitude training camps

AimTo quantify the year-to-year variability of altitude-induced changes in haemoglobin mass (Hbmass) in elite team-sport athletes.Methods12 Australian-Footballers completed a 19-day (ALT1) and 18-day (ALT2) moderate altitude (∼2100 m), training camp...

Ten days of simulated live high:train low altitude training increases Hbmass in elite water polo players

ObjectivesWater polo requires high aerobic power to meet the demands of match play. Live high:train low (LHTL) may enhance aerobic capacity at sea level. Before the Olympics, the Australian women's...

Relationship between changes in haemoglobin mass and maximal oxygen uptake after hypoxic exposure

BackgroundEndurance athletes have been using altitude training for decades to improve near sea-level performance. The predominant mechanism is thought to be accelerated erythropoiesis increasing haemoglobin mass (Hbmass) resulting in a...