Wachsmith, N. B., Kelley, M., Feriche, B., Calderon, C., Iglesias, X., Rodriguez, F. A., & Schmidt, W. F. (2014). Influencing factors on the erythropoietic response during altitude training (Altitude Project). Medicine & Science in Sports & Exercise, 46(5), Supplement abstract number 1575.

This study ascertained the range of individual changes in hemoglobin mass in response to altitude training in elite swimmers (M = 26; F = 35), and identified possible influencing factors on observed responses. Ss were from seven teams and eight countries. Five teams formed the altitude group (M = 20; F = 24) and completed a 3-4 weeks altitude training camp at 2,320 m at Sierra Nevada (Spain). At the same time, two control groups (M = 6, F = 11) performed a training camp at near sea level (Madrid and Barcelona, Spain). Hemoglobin mass was measured before, every week during the camps, and at the end using the optimized CO-rebreathing method. Training load was quantified using the TRIMP heart rate-based method. The impact of the following parameters on hemoglobin mass changes were analyzed using a mixed model: TRIMPs, time at altitude, health and iron status, usage of non-steroidal anti-inflammatory drugs, volume of blood drawn for analytical purposes, and training strategy (living and training at altitude and/or sea-level).

No change in hemoglobin mass occurred at sea-level. The first increase in mean hemoglobin mass was observed after two weeks at altitude and reached a maximum mean of 4.2% at the end of the altitude training camp. There were large variations between individuals (range between -4.4 and 12.0%) and among teams (range of mean values (±SD) between 0.7 ± 2.5% and 8.6 ± 4.0%). Beside time at altitude as a positive factor, other significant inhibitory factors were non-steroidal anti-inflammatory drugs (5 tablets) and volume of blood drawn. TRIMPS per week were negatively and lowly correlated with the change in hemoglobin mass (r = -0.3). No effect was found related to altitude training strategy.

Implication. Changes in hemoglobin mass in response to altitude training are largely individual and can be negatively affected, in addition to known factors such as low iron stores and illness or injury, by a continuous intake of non-steroidal anti-inflammatory drugs. A high training load also may impact negatively on the erythropoietic response.

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