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

• Published in: Journal of applied physiology (1985) 2024-01, Vol.136 (1), p.1-12
• Main Authors: Lundby, Carsten, Mazza, Oscar, Nielsen, Joachim, Haubro, Mads, Kvorning, Thue, Ørtenblad, Niels, Gejl, Kasper Degn
• Format: Article
• Language: English
• ISSN: 8750-7587; 1522-1601
• DOI: 10.1152/japplphysiol.00587.2023

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 wk with three weekly sessions of conventional (3-SET: 3 × 10 reps) or high-volume strength training (10-SET: 5-10 × 10 reps) on LBM, Hb , muscle strength, and exercise performance in female and male rowers. Hematological parameters were obtained through CO rebreathing and body composition by dual-energy X-ray absorptiometry (DEXA) scans before and after the training period. Concomitantly, V̇o was determined during 2-km ergometer rowing and muscle strength by isometric midthigh 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 ± 199 g to 897 ± 213 g; 3-SET: 936 ± 245 g to 962 ± 247 g, = 0.02) and V̇o (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), whereas LBM remained unchanged (10-SET: 58.7 ± 10.5 to 58.7 ± 10.1 kg; 3-SET: 64.1 ± 10.8 to 64.5 ± 10.6 kg, = 0.42). Maximal isometric midthigh pull strength increased (10-SET: 224 ± 47 kg to 237 ± 55 kg; 3-SET: 256 ± 77 kg to 281 ± 83 kg, = 0.001). Strong associations were observed between LBM and Hb and V̇o ( = 0.88-0.90), entailing sex differences in Hb and V̇o . Normalizing V̇o to LBM reduced the sex difference to ∼10%, aligning with the sex difference in Hb ·LBM . Strength training successfully increased Hb and V̇o in elite female and male rowers, without an additional effect from increased training volume. Moreover, sex differences in V̇o were mainly explained by differences in LBM, but likely also by differences in Hb ·LBM . This study in female and male rowers demonstrates that hemoglobin mass (Hb ), V̇o , and muscle strength increases with 8 wk of heavy strength training and that this response is not different between conventional (3 × 10 repetitions) and high-volume strength training (10 × 10 repetitions). Moreover, female rowers exhibited less hemoglobin per kilogram of lean body mass compared with their male counterparts, which likely contributes to sex differences in V̇o and rowing performance.