Continuous cycling at an intermediate work rate elicited a lower maximal cardiac output than an incremental test (24.4 vs 28.4 L/min; P<0.05), despite attaining the same VO2max.
Does exercise intensity affect the central and peripheral factors (cardiac output and stroke volume) at which VO2max is attained in well-trained males?
VO2max is not attained with the same central and peripheral factors across different exhaustive exercise intensities, as submaximal exhaustive exercise does not elicit maximal cardiac output.
Absolute Event Rate: 24.4% vs 28.4%
p-value: p=<0.05
PURPOSE: The purpose of this study was to determine whether the maximal oxygen uptake (VO2max) is attained with the same central and peripheral factors according to the exercise intensity. METHODS: Nine well-trained males performed an incremental exercise test on a cycle ergometer to determine the maximal power associated with VO2max (pVO2max) and maximal cardiac output (Qmax). Two days later, they performed two continuous cycling exercises at 100% (tlim100 = 5 min 12 s +/- 2 min 25 s) and at an intermediate work rate between the lactate threshold and pVO2max (tlimDelta50 +/- 12 min 6 s +/- 3 min 5 s). Heart rate and stroke volume (SV) were measured (by impedance) continuously during all tests. Cardiac output (Q) and arterial-venous O2 difference (a-vO2 diff) were calculated using standard equations. RESULTS: Repeated measures ANOVA indicated that: 1) maximal heart rate, VE, blood lactate, and VO2 (VO2max) were not different between the three exercises but Q was lower in tlimDelta50 than in the incremental test (24.4 +/- 3.6 L x min(-1) vs 28.4 +/- 4.1 L x min(-1); P < 0.05) due to a lower SV (143 +/- 27 mL x beat(-1) vs 179 +/- 34 mL x beat(-1); P < 0.05), and 2) maximal values of a-vO2 diff were not significantly different between all the exercise protocols but reduced later in tlimDelta50 compared with tlim100 (6 min 58 s +/- 4 min 29 s vs 3 min 6 s +/- 1 min 3 s, P = 0.05). This reduction in a-vO2 diff was correlated with the arterial oxygen desaturation (SaO2 = -15.3 +/- 3.9%) in tlimDelta50 (r = -0.74, P = 0.05). CONCLUSION: VO2max was not attained with the same central and peripheral factors in exhaustive exercises, and tlimDelta50 did not elicit the maximal Q. This might be taken into account if the training aim is to enhance the central factors of VO2max using exercise intensities eliciting VO2max but not necessarily Qmax.
Leprêtre et al. (Sun,) conducted a other in Healthy (well-trained males) (n=9). Continuous cycling exercise at intermediate work rate (tlimDelta50) vs. Incremental exercise test and continuous cycling at 100% pVO2max was evaluated on Maximal cardiac output (Q) (p=<0.05). Continuous cycling at an intermediate work rate elicited a lower maximal cardiac output than an incremental test (24.4 vs 28.4 L/min; P<0.05), despite attaining the same VO2max.