Increased cardiac output elicits higher V̇O_2max in response to self-paced exercise

Abstract

Recently, a self-paced protocol demonstrated higher maximal oxygen uptake versus the traditional ramp protocol. The primary aim of the current study was to further explore potential differences in maximal oxygen uptake between the ramp and self-paced protocols using simultaneous measurement of cardiac output. Active men and women of various fitness levels (N = 30, mean age = 26.0 ± 5.0 years) completed 3 graded exercise tests separated by a minimum of 48 h. Participants initially completed progressive ramp exercise to exhaustion to determine maximal oxygen uptake followed by a verification test to confirm maximal oxygen uptake attainment. Over the next 2 sessions, they performed a self-paced and an additional ramp protocol. During exercise, gas exchange data were obtained using indirect calorimetry, and thoracic impedance was utilized to estimate hemodynamic function (stroke volume and cardiac output). One-way ANOVA with repeated measures was used to determine differences in maximal oxygen uptake and cardiac output between ramp and self-paced testing. Results demonstrated lower (p < 0.001) maximal oxygen uptake via the ramp (47.2 ± 10.2 mL·kg(-1)·min(-1)) versus the self-paced (50.2 ± 9.6 mL·kg(-1)·min(-1)) protocol, with no interaction (p = 0.06) seen for fitness level. Maximal heart rate and cardiac output (p = 0.02) were higher in the self-paced protocol versus ramp exercise. In conclusion, data show that the traditional ramp protocol may underestimate maximal oxygen uptake compared with a newly developed self-paced protocol, with a greater cardiac output potentially responsible for this outcome.

Age differences in physiological responses to self-paced and incremental $$\dot{V}{\text{O}}_{2\hbox{max} }$$ V ˙ O 2 max testing

“…In support of previous literature (Astorino et al 2015; Mauger and Sculthorpe 2012; Mauger et al 2013), the results of the current study demonstrate that younger participants were able to achieve a significantly higher in the SPV compared to the RAMP protocol. However, this was not evident in the older population where there were no differences in between the two protocols.…”

“…The SPV has been shown to allow young participants to achieve a higher when compared to a standard incremental exercise test in both cycling and running exercise modes (Astorino et al 2015; Mauger and Sculthorpe 2012; Mauger et al 2013), although a mechanistic explanation is yet to be identified. However, not all studies have found differences in when comparing the SPV vs. standard incremental exercise protocols (Chidnok et al 2013; Faulkner et al 2015; Straub et al 2014).…”

“…A recent study has demonstrated that the SPV may elicit a greater cardiac output ( Q ) and peak HR when compared to a standard incremental ramp protocol (Astorino et al 2015). The study by Astorino et al (2015) was the first to assess Q across the SPV, and suggests that the greater may be explained by an increase in oxygen delivery (Mortensen et al 2005), rather than an increase in the oxygen extraction as previously suggested.…”

Graded Exercise Testing Protocols for the Determination of VO2max: Historical Perspectives, Progress, and Future Considerations

“…This study also received criticisms over flawed methods and lack of control, attributing findings to using different modes (motorized versus nonmotorized treadmill) and neglect of measurement error to test their hypothesis [83, 87–89]. Follow-up studies have shown a higher VO 2 max attainment during self-pacing using a cycle ramp protocol [90], similar VO 2 max attainment using motorized treadmill [83, 91–93] and cycle protocols [84, 94], and a lower VO 2 max attainment using an automated treadmill [89]. It is important to note that findings showing no difference between self-paced and traditional protocols demonstrate the potential utility for self-paced GXT protocols, particularly when considering protocol duration.…”

“…It is purported that underlying variables that comprise the Fick equation, namely, Q and a-vO 2diff , and the role of blood flow redistribution may underpin differences between self-paced and traditional protocols [92, 93]. More recently, Astorino et al [90] showed that a self-paced cycle protocol elicited higher VO 2 compared to a ramp protocol (50.2 ± 9.6 versus 47.2 ± 10.2 mL·kg −1 ·min −1 ). Additionally, they were the first to compare central cardiovascular responses between protocols and showed a higher Q max during self-paced compared to ramp (21.9 ± 3.7 versus 20.7 ± 3.4 L·min −1 ).…”