Spleen emptying does not correlate with faster oxygen kinetics during a step-transition supine cycling

Zubac, Damir; Obad, Ante; Bošnjak, Ana; Zec, Mirela; Ivančev, Vladimir; Valić, Zoran

doi:10.1139/apnm-2021-0294

Cited by 2 publications

(7 citation statements)

References 24 publications

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“…This step-transition protocol was repeated three times, interspersed with 20 min. of rest, in agreement with previously published work (Zubac et al 2021a ). An overview of the data collection is shown in Fig.…”

Section: Methodssupporting

confidence: 93%

“…The parameters at 90% GET ( , time delay, kinetics amplitude) were modeled using mono-exponential, least-squares regression (Eq. 1 ), from the fundamental component onset to the 4th minute, when steady-state was reached, as suggested in the literature (DeLorey et al 2004 ; Mezzani et al 2010 ) and previously used by our laboratory (Zubac et al 2021a , c ). The equation parameters are explained in detail elsewhere (DeLorey et al 2004 ; Mezzani et al 2010 ; Zubac et al 2021c ).…”

Section: Methodsmentioning

confidence: 85%

“…Accordingly, a clear image of the contracting spleen was obtained throughout the experimental procedure. We found that splenic volume was reduced by 36%, while greater splenic emptying was not correlated with faster O 2 kinetics, independent of the subsequent RBC release (Zubac et al 2021a ). Nevertheless, the role of splenic emptying in O 2 transport during aerobic exercise remains a controversial topic.…”

Section: Introductionmentioning

confidence: 86%

“…We took special attention to standardize all supine cycling procedures on custom-designed setup and data collection protocols. The distances between the crankshaft, shoulder and pelvis distance were recorded for each participant, and then replicated throughout the study (Goulding et al 2020a , b ; Goulding et al 2021 ; Zubac et al 2021a ). To reduce torso movement in the supine position and to improve ultrasonographic imaging of the spleen all participants were restrained to a bed during the supine position.…”

Section: Methodsmentioning

confidence: 99%

“…The intra-assay reliability of the spleen imaging during the study was satisfactory (CV = 2%). Splenic volumes from the images were calculated as originally suggested by Koga and Morikawa ( 1975 ), Koga ( 1979 ), and later adopted in our previous work (Palada et al 2007 ; Bakovic et al 2012 ; Zubac et al 2021a ).…”

Section: Methodsmentioning

confidence: 99%

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No differences in splenic emptying during on-transient supine cycling between aerobically trained and untrained participants

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Purpose The role of splenic emptying in O 2 transport during aerobic exercise still remains a matter of debate. Our study compared the differences in spleen volume changes between aerobically trained and untrained individuals during step-transition supine cycling exercise at moderate-intensity. We also examined the relationship between spleen volume changes, erythrocyte release, and O 2 uptake parameters. Methods Fourteen healthy men completed all study procedures, including a detailed medical examination, supine maximal O 2 uptake ( max.) test, and three step-transitions from 20 W to a moderate-intensity power output, equivalent to uptake at 90% gas exchange threshold. During these step-transitions pulmonary , near-infrared spectroscopy of the vastus lateralis , and cardiovascular responses were continuously measured. In parallel, minute-by-minute ultrasonic measurements of the spleen were performed. Blood samples were taken before and immediately after step-transition cycling. Results On average, max. was 10 mL kg min −1 ( p = 0.001) higher in trained compared to their aerobically untrained peers. In response to supine step-transition cycling, the splenic volume was significantly reduced, and the largest reduction (~ 106 to 115 mL, ~ 38%, p = 0.001) was similar in both aerobically trained and untrained individuals. Erythrocyte concentration and platelet count transiently increased after exercise cessation, with no differences observed between groups. However, the vastus lateralis deoxygenation amplitude was 30% ( p = 0.001) greater in trained compared to untrained individuals. No associations existed between: (i) spleen volumes at rest (ii) spleen volume changes (%), (iii) resting hematocrit and oxygen uptake parameters. Conclusion Greater splenic emptying and subsequent erythrocyte release do not lead to a slower , regardless of individual max. readings.

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Section: Methodssupporting

confidence: 93%

Section: Methodsmentioning

confidence: 85%

Section: Introductionmentioning

confidence: 86%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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No differences in splenic emptying during on-transient supine cycling between aerobically trained and untrained participants

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Determination of exercise intensity domains during upright versus supine cycling: a methodological study

Zubac

Ivančev

Martín

et al. 2022

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Background There is a growing interest among the research community and clinical practitioners to investigate cardiopulmonary exercise test (CPET) procedures and protocols utilized in supine cycling. Materials and Methods The current study investigated the effects of posture on indicators of exercise intensity including gas exchange threshold (GET), respiratory compensation point (RCP), and the rate of peak oxygen uptake (V̇O2 peak), as well as the role of V̇O2 mean response time (MRT) in determining exercise intensity domains in nineteen healthy men (age: 22 ± 3 years). Two moderate-intensity step-transitions from 20 to 100 Watt (W) were completed, followed by a maximal CPET. After completing the ramp test, participants performed a constant-load at 90% of their attained peak power output (PPO). Results No differences were observed in the V̇O2 MRT between the two positions, although the phase II-time constant (τV̇O2p) was 7 s slower in supine position compared to upright (p = 0.001). The rate of O2 uptake in the supine position at GET and RCP were lower compared to the upright position (208 ± 200 mL·min−1 (p = 0.007) and 265 ± 235 mL·min−1 (p = 0.012) respectively). Besides, V̇O2 peak was significantly decreased (by 6%, p = 0.002) during supine position. These findings were confirmed by the wide limits of agreement between the measures of V̇O2 in different postures (V̇O2 peak: −341 to 859; constant-load test: −528 to 783; GET: −375 to 789; RCP: −520 to 1021 all in mL·min−1). Conclusion Since an accurate identification of an appropriate power output (PO) from a single-visit CPET remains a matter of debate, especially for supine cycling, we propose that moderate-intensity step-transitions preceding a ramp CPET could be a viable addition to ensure appropriate exercise-intensity domain determination, in particular upon GET-based prescription.

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Spleen emptying does not correlate with faster oxygen kinetics during a step-transition supine cycling

Cited by 2 publications

References 24 publications

No differences in splenic emptying during on-transient supine cycling between aerobically trained and untrained participants

No differences in splenic emptying during on-transient supine cycling between aerobically trained and untrained participants

Determination of exercise intensity domains during upright versus supine cycling: a methodological study

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