Eight weeks of heavy strength training increases hemoglobin mass and V̇O 2 peak in well-trained to elite female and male rowers.

O-transport and endurance exercise performance are greatly influenced by hemoglobin mass (Hb), which largely depends on lean body mass (LBM). This study investigated the effects of 8 weeks with 3 weekly sessions of conventional (3-SET: 3x10 reps) or high-volume strength training (10-SET: 5-10x10 reps) on LBM, Hb, muscle strength, and exercise performance in female and male rowers. Hematological parameters were obtained through CO re-breathing and body composition by DEXA scans before and after the training period. Concomitantly, V̇Opeak was determined during 2-km ergometer rowing and muscle strength by isometric mid-thigh pull. There were no differences in training responses between groups for any of the parameters. Pooled data, revealed overall increments for Hb (10-SET: 882±199g to 897±213g; 3-SET: 936±245g to 962±247g, =0.02) and V̇Opeak (10-SET: 4.3±1.0 to 4.4±0.9 L∙min; 3-SET: 4.5±0.9 to 4.6±0.9 L∙min, =0.03), while LBM remained unchanged (10-SET: 58.7±10.5 to 58.7±10.1kg; 3-SET: 64.1±10.8 to 64.5±10.6kg, =0.42). Maximal isometric mid-thigh pull strength increased (10-SET: 224±47kg to 237±55kg; 3-SET: 256±77kg to 281±83kg, =0.001). Strong associations were observed between LBM and Hb and V̇Opeak (r=0.88-0.90), entailing sex differences in Hb and V̇Opeak. Normalizing V̇Opeak to LBM reduced the sex difference to ~10%, aligning with the sex difference in Hb∙LBM. Strength training successfully increased Hb and V̇Opeak in elite female and male rowers, without an additional effect from increased training volume. Moreover, sex differences in V̇Opeak were mainly explained by differences in LBM, but likely also by differences in Hb∙LBM.