Letter to the Editors

Dear Editors,

We read with interest the altitude training study of Heinicke et al. with 10 world-class biathletes. We were very surprised by their finding that 19 days at 2050 m was sufficient to increase haemoglobin mass (Hb_mass) by 9.3 % (14.0 ± 0.2 to 15.3 ± 1.0 g/kg). Effects of this magnitude cannot be accepted without scrutiny. Although there is no doubt about elevated Hb_mass of lifelong residents [[7]] of moderate altitude (2600 - 3550 m), including athletes [[15]], the influence of 3 - 4 weeks at 2100 - 2500 m is more controversial [[6]], particularly since this level of altitude is around the threshold required to stimulate a sustained 24-hour increase in EPO in most people [[3]].

It would have been useful if Heinicke had measured both V·O_2max and performance, such as a 10-km ski leg, to corroborate the apparent increase in Hb_mass. Saltin [[13]], we [[6]], and Rusko et al. [[12]] have each reviewed the extensive literature associated with conventional altitude training, now commonly called living high and training high (LHTH). Independently, all three reviews concluded that controlled studies provide no convincing evidence that LHTH increases V·O_2max or performance at sea level. Unfortunately, a control group was not included in the study of Heinicke. Consequently, the effects of intensive training cannot be separated from the effects of altitude; and Sawka et al. [[14]] after reviewing multiple training studies estimated a ∼ 10 % increase in red cell volume after 2 - 3 weeks of training, albeit in previously untrained groups. On the other hand, Berglund [[1]] has estimated that the true rate of increase in haemoglobin is ∼ 1 %/week for athletes training at moderate altitude. A group mean increase of 9 % among athletes is quite extraordinary in 19 days.

The five-fold increase in the SD of the group Hb_mass from day-1 to day-20 at altitude implies substantial individual variation; that some athletes may have “changed” by ∼ 0 % and some by + 20 %. Individual changes as large as 20 % would be extreme. In this context it is relevant to consider that the most common source of error with the CO rebreathing method for estimating Hb_mass is leakage of air around the mouthpiece or noseclip. A leak substantially increases, and never decreases, the measured Hb_mass. Moreover larger doses of CO ameliorate the magnitude of error [[2]], but the dose used by Heinicke (60 ml at 2000 m) is equivalent to ∼ 50 ml at sea level and prone to more error for subjects with a larger Hb_mass [[2]].

Although Heinicke et al. measured soluble transferrin concentration (sTfr), which is arguably a primary indicator of accelerated red cell production [[5], [9]], their results are inconsistent, with an increase in sTfr of the men but not the women at day-10 and day-20 at altitude, despite a similar percentage increase in Hb_mass for both sexes.

If the reported increase in Hb_mass was not induced by training or influenced by one or two extreme instances of measurement error, a question must be raised as to whether the researchers can exclude the use of pharmacological blood boosting modalities by the athletes while at altitude. Concurrent use of altitude and recombinant human erythropoietin (r-HuEPO), or darbepoietin (Aranaesp®), or blood infusion would each increase Hb_mass [[11]] and performance [[4]]. A urine test for r-HuEPO has only been available since 2000 [[10]] and more than 40 positive results have been reported in the media. These ranged from a 43-year-old Masters distance runner in the USA to a 16-year-old South African cyclist, a participant in the Bomax Junior Cycle Tour. The preponderance of positive results that we have located were for cyclists. None were for biathletes, but in the allied sport of cross-country skiing seven individuals have been sanctioned for EPO use and three for darbepoietin.

We respectfully suggest, that future studies of LHTH should use a matched control group and include assessment of V·O_2max and performance to corroborate any increase in Hb_mass, given the close association between these variables [[8]]. Duplicate baseline measures instead of single pre-intervention measures would also instil greater confidence in any observed changes. However, critically lacking in the literature is a systematic examination of the time course of Hb_mass with exercise training in elite athletes. Such data would help separate the changes that occur with training from those that might occur at altitude.

References

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