WARBURTON, D. E. R., M. J. HAYKOWSKY, H. A. QUINNEY, D. BLACKMORE, K. K. TEO, D. A. TAYLOR, J. MCGAVOCK, and D. P. HUMEN. Blood Volume Expansion and Cardiorespiratory Function: Effects of Training Modality. Med. Sci. Sports Exerc., Vol. 36, No. 6, pp. 991–1000, 2004.
Purpose: To evaluate the effects of different modalities of aerobic (i.e., interval (INT) and continuous (CONT)) training on cardiorespiratory function and the importance of training-induced blood volume (BV) expansion on aerobic power and LV function. We hypothesized that if modality-mediated differences in cardiorespiratory function exist after INT and CONT, they would be related directly to differences in training-induced hypervolemia.
Methods: We examined the effects of 12 wk of CONT and INT on BV, volume-regulatory hormones (angiotensin II, aldosterone, atrial natriuretic peptide), and cardiorespiratory function in 20 untrained males (mean age 30 ± 4 (SD)). Participants were stratified (mass and V̇O2max) and randomly assigned to control, CONT, or INT.
Results: There were no significant changes in cardiorespiratory function or BV in the control group. Twelve weeks of continuous and interval training, respectively, resulted in significant changes in V̇O2max (23 ± 18 vs 21 ± 10%), peak stroke volume (20 ± 18 vs 11 ± 18%), and BV (12 ± 9 vs 10 ± 6%). Changes in V̇O2max were directly related to changes in BV (r2 = 0.47). Angiotensin II significantly increased after 1 wk of CONT and INT and thereafter returned to baseline values. There was no significant difference between the CONT and INT groups with regard to changes in vascular volumes, volume-regulatory hormones, and/or cardiorespiratory function.
Conclusions: These data indicate that: 1) 12 wk of CONT and INT result in similar improvements in V̇O2max, and LV function and 2) training-induced hypervolemia accounts for approximately 47% of the changes in V̇O2max after CONT and INT.