Purpose Altitude training is a common strategy used with the intent to increase hemoglobin mass (Hbmass) in athletes. However, if the Hbmass is increased during altitude camps, it seems to decline rapidly upon returning to sea level. This study aimed to examine the efficacy of three weekly heat training sessions over a 3.5-wk period after a 3-wk altitude camp on the maintenance of Hbmass in elite cyclists. Methods Eighteen male cyclists (maximal oxygen consumption: 76 ± 5 mL·min-1·kg-1) underwent a 3-wk altitude training camp at ~2100 m above sea level. After the camp, participants were divided into one group performing three weekly heat sessions that were subtracted from their usual training (HEAT) while the other continuing usual training (CON). Training characteristics were recorded during the intervention, whereas hematological measurements were recorded before the camp as well as 2 d and 3.5 wk after the altitude camp. Results The 3-wk altitude camp led to an overall increase in total Hbmass of 4.1%. Afterward, HEAT maintained Hbmass (0.2%, P = 0.738), whereas CON group experienced a significant reduction (-3.3%, P < 0.001) (Delta-HEAT vs Delta-CON, P < 0.001). Moreover, HEAT increased plasma volume (PV) by 11.6% (P = 0.007) and blood volume (BV) by 5.8% (P = 0.007), whereas CON only showed an increase in PV (5.5%, P = 0.041). Exercise intensity and training load were not different between groups during the maintenance period. Conclusions This study suggests that incorporating three weekly heat training sessions into the usual training routine preserves a moderately increased Hbmass in elite cyclists after an altitude camp.
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