Cardiovascular and hemodynamic responses on dryland vs. immersed cycling

Objectives: To investigate the effect of water immersion on oxygen uptake ((702) and central hemodynamic responses during incremental maximal exercise at the same external power output (P-ext) and recovery on an immersible ergocycle vs. a dryland ergocycle. Design: Cross-over design study. Methods: Twenty healthy participants (32 +/- 7 years; 173 +/- 6 cm; 71.7 +/- 9.7 kg) performed maximal incremental exercise tests while pedalling either immersed on immersible ergocycle (Hydrorider (R)) or on dryland ergocycle (Ergoline 800S; Bitz, Germany). Initial Pext of dryland ergocycle protocol was set at 25W and increased by 25W every minute until exhaustion. P-ext on immersible ergocycle was controlled by pedalling rate (rpm). Initial rpm was set at 40 rpm and was increased by 1 0 rpm until 70 rpm and thereafter by 5 rpm until exhaustion. Gas exchange and central hemodynamic parameters were measured continuously during exercise and a 5-min recovery period. Reported (V) over dotO(2), stroke volume, cardiac output ((Q) over dot) and arteriovenous difference (C(a-v)O-2) were compared. Results: During exercise on immersible ergocycle, (V) over dotO(2) and C(a-v)O-2 were lower (P<0.0001) whereas stroke volume and (Q) over dot were higher (P<0.05) relative to a dryland ergocycle exercise of equivalent P-ext. Conclusions: During exercise and recovery in immersion, ((V) over dotO(2)) and arteriovenous difference were reduced in healthy young participants, while stroke volume and cardiac output were increased for the same P-ext. During the recovery, central hemodynamics responses remained higher in immersible ergocycle. (C) 2014 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.