Background: The effects of repeated "live high-train high" training camps on total hemoglobin mass (tHBmass) in female team-sport athletes have not been investigated. Purpose: To assess whether the changes in tHBmass were repeatable in 16 world-class female water polo players during successive live high-train high camps at 2320 m, separated by 24 weeks, in preparation of international championships. Methods: tHBmass was measured by optimized carbon monoxide rebreathing before and after each camp, lasting 16 and 14 days, respectively. In addition, resting heart rate, peripheral oxygen saturation, body mass, fatigue, and sleep were monitored daily during both camps. Results: Changes in tHbmass appeared not to be associated between the 2 camps (Hedges g = -0.81; P = .05; 95% CI, -1.68 to 0.06) nor with prealtitude tHbmass (camp 1: ß = -0.04; P = .89; 95% CI, -0.61 to 0.54; camp 2: ß = -0.42; P = .10; 95% CI, -0.94 to 0.10) or with prealtitude ferritin concentration (camp 1: ß = -0.4; P = .14; 95% CI, -0.91 to 0.15; camp 2: ß = 0.02; P = .95; 95% CI, -0.61 to 0.65). tHBmass values were correlated between the end of camp 1 and the start of camp 2 (r = .94; P < .001; 95% CI, .82-.98). Improved sleep quality in camp 1 was associated with an increase in tHBmass (ß = 0.51; P = .04; 95% CI, 0.02 to 1.00). Conclusion: We observed a highly variable pattern of tHBmass responses in female water polo players undertaking 2 altitude training camps ~5 months apart. Individualized training and management plans are likely required to complement team practices in altitude training camps undertaken by female team-sport athletes.
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