A routine method to determine total haemoglobin mass (tHb) in clinical practice and sports medicine is non-existent. Radioactive tracers or other dilution procedures like the common CO-rebreathing method (Proccom) are impractical, the latter in particular because of the relatively long time of respiration. According to the multicompartment model of Bruce and Bruce (J Appl Physiol 95:1235–1247, 2003) the respiration time can be considerably reduced by inhaling a CO-bolus instead of the commonly used gas mixture. The aim of this study was to evaluate this theoretical concept in practice. The kinetics of the HbCO formation were compared in arterialised blood sampled from an hyperaemic earlobe after inhaling a CO-bolus (Procnew) for 2 min and a CO–O2 mixture (Proccom) for ∼10 min. The reliability of Procnew was checked in three consecutive tests, and phlebotomy was used to determine the validity. VO2max was determined with and without previous application of Procnew and the half-time of HbCO was registered also in arterialised blood after resting quietly and after the VO2max test. Procnew yielded virtual identical tHb values compared to Proccom when HbCO determined 5 min after starting CO-rebreathing was used for calculation. The typical error of Procnew was 1.7%, corresponding to a limit of agreement (95%) of 3.3%. The loss of 95 g (19) haemoglobin was detected with an accuracy of 9 g (12). After application of Procnew
 VO2max was reduced by 3.0% (3.7) (P=0.022) and half-time was lowered from 132 min (77) to 89 min (23) after the VO2max test. Inhaling a CO-bolus markedly simplifies the CO-rebreathing method without reducing validity and reliability and can be used for routine determination of tHb for various indications.

The optimised CO-rebreathing method: a new tool to determine total haemoglobin mass routinely

Cardiac Origins of the Postural Orthostatic Tachycardia Syndrome

BACKGROUND AND OBJECTIVE: The use of recombinant human erythropoietin (r-HuEPO) to enhance athletic performance is prohibited. Existing tests cannot readily differentiate between exogenous and endogenous EPO. Therefore the aim of our study was to investigate possible indirect detection of r-HuEPO use via blood markers of altered erythropoiesis. DESIGN AND METHODS: Twenty-seven recreational athletes were assigned to three groups prior to a 25 day drug administration phase, with the following protocols: EPO+IM group (n = 10), 50 Ukg(-1) r-HuEPO at a frequency of 3wk(-1), 100 mg intramuscular (IM) iron 1wk(-1) and a sham iron tablet daily; EPO+OR group (n = 8), 50 U.kg(-1) r-HuEPO 3wk(-1), sham iron injection 1wk(-1) and 105 mg of oral elemental iron daily; placebo group (n = 9), sham r-HuEPO injections 3wk(-1), sham iron injections 1wk(-1) and sham iron tablets daily. Each group was monitored during and for 4 weeks after drug administration. RESULTS: Models incorporating combinations of the variables reticulocyte hematocrit (RetHct), serum EPO, soluble transferrin receptor, hematocrit (Hct) and % macrocytes were analyzed by logistic regression. One model (ON-model) repeatedly identified 94-100% of r-HuEPO group members during the final 2 wk of the r-HuEPO administration phase. One false positive was recorded from a possible 189. Another model (OFF-model) incorporating RetHct, EPO and Hct was applied during the wash-out phase and, during the period of 12-21 days after the last r-HuEPO injection, it repeatedly identified 67-72% of recent users with no false positives. INTERPRETATION AND CONCLUSIONS: Multiple indirect hematologic and biochemical markers used simultaneously are potentially effective for identifying current or recent users of r-HuEPO.

A novel method utilising markers of altered erythropoiesis for the detection of recombinant human erythropoietin abuse in athletes

Six sessions of high-intensity interval training (HIT) are sufficient to improve exercise capacity. The mechanisms explaining such improvements are unclear. Accordingly, the aim of this study was t...

Improvements in exercise performance with high-intensity interval training coincide with an increase in skeletal muscle mitochondrial content and function.

Key points
The prevalence of cardiorespiratory fitness (CRF) non-response gradually declines in healthy individuals exercising 60, 120, 180, 240 or 300 min per week for 6 weeks.
Following a successive identical 6-week training period but comprising 120 min of additional exercise per week, CRF non-response is universally abolished.
The magnitude of CRF improvement is primarily attributed to changes in haemoglobin mass.
The potential for CRF improvement may be present and unveiled with appropriate exercise training stimuli in healthy individuals without exception.


Abstract
One in five adults following physical activity guidelines are reported to not demonstrate any improvement in cardiorespiratory fitness (CRF). Herein, we sought to establish whether CRF non-response to exercise training is dose-dependent, using a between- and within-subject study design. Seventy-eight healthy adults were divided into five groups (1–5) respectively comprising one, two, three, four and five 60 min exercise sessions per week but otherwise following an identical 6-week endurance training (ET) programme. Non-response was defined as any change in CRF, determined by maximal incremental exercise power output (Wmax), within the typical error of measurement (±3.96%). Participants classified as non-responders after the ET intervention completed a successive 6-week ET period including two additional exercise sessions per week. Maximal oxygen consumption (VO2 max ), haematology and muscle biopsies were assessed prior to and after each ET period. After the first ET period, Wmax increased (P < 0.05) in groups 2, 3, 4 and 5, but not 1. In groups 1, 2, 3, 4 and 5, 69%, 40%, 29%, 0% and 0% of individuals, respectively, were non-responders. After the second ET period, non-response was eliminated in all individuals. The change in VO2 max with exercise training independently determined Wmax response (partial correlation coefficient, rpartial ≥ 0.74, P < 0.001). In turn, total haemoglobin mass was the strongest independent determinant of VO2 max (rpartial = 0.49, P < 0.001). In conclusion, individual CRF non-response to exercise training is abolished by increasing the dose of exercise and primarily a function of haematological adaptations in oxygen-carrying capacity.

https://physoc.onlinelibrary.wiley.com/doi/pdf/10.1113/JP273480

Refuting the myth of non-response to exercise training: 'non-responders' do respond to higher dose of training

An improved protocol was applied to the use of carboxyhemoglobin (HbCO) saturation for the estimation of body hemoglobin (Hb) mass, red blood cell volume, and blood volume and was appraised in norm...

C. M. Burge

Papers

Determination of hemoglobin mass and blood volume with CO: evaluation and application of a method