Persisting Elevation of Total Hemoglobin Mass After Altitude Training in Elite Swimmers: a Potential Role of Prolonged Erythrocyte Survival.

Altitude training camps are frequently used by endurance athletes to increase total hemoglobin mass (Hb) and potentially aerobic performance. However, the effects of such intervention on red blood cell (RBC) properties remain largely unexplored, although these factors could influence the physiological responses following altitude training. This self-controlled study investigated the effects of a "Live High-Train High" (LHTH) altitude training camp on RBC senescence and Hb in 9 elite swimmers. Participants performed two 4-week training camps, one at 1850 m altitude (LHTH) and the other one at sea level (SL). Hb, hematocrit, RBC senescence and deformability were measured before and immediately after both training camps, and again 10 days after the LHTH camp. A 400-m freestyle 'all-out' swimming test was performed before and 10 days after each training camp (n=6). Hb, hematocrit, CD71-positive RBCs, RBC phosphatidylserine exposure and the percentage of RBC retaining mitochondria were increased after LHTH camp. RBC reactive oxygen species content was increased after both interventions, whereas RBC deformability and CD47 expression remained unchanged. While LHTH camp was accompanied by an increase in RBC senescence markers, Hb remained increased 10 days post-LHTH. Although 400-m swimming performance was not significantly improved 10 days post-LHTH (-3.8 ± 5.1s), its change was associated with Hb variations. These results indicate that a 4-week LHTH camp (1850 m) is accompanied by an increase in Hb, which persists for up to 10 days after the camp, despite the increase in RBC senescence markers, a persistence that could be explained by a prolonged RBC survival.