Solving the Fick principle using whole body measurements does not discriminate “central” and “peripheral” adaptations to training

Poole, David C.; Musch, Timothy I.

doi:10.1007/s00421-007-0668-4

Cited by 10 publications

(8 citation statements)

References 6 publications

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“…We agree that we observed a small elevation in _ Q max and compared to the substantial increase of _ VO 2 max : However, the ratio between D _ Q _ Q max À _ Q rest À Á and D _ VO 2 _ VO 2 max À _ VO 2rest À Á was 6.8 before training and went down to 6.1 after training, both being values similar to those documented in the literature (Taivassalo et al 2003) and there are in accordance with remarks of Poole and Musch (Poole and Musch 2008).…”

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confidence: 88%

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Solving the Fick principle using whole body measurements can be used to discriminate ‘‘central’’ and ‘‘peripheral’’ adaptations to training

2008

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We have read with attention the letter from Drs. Poole and Musch (Poole and Musch 2008) and we thank them for giving us the opportunity to explain in further details our methodology and interpretations. To clarify the ideas developed in our paper, we would like to go back to some of the definitions related to the key parameters we have used. In the original study (Daussin et al. 2007), maximal arteriovenous oxygen difference D aÀ" v O 2 max ð Þwas determined, according to the Fick equation, by dividing maximal oxygen consumption _ VO 2 max À Á by maximal cardiac output _ Q max À Á and is often considered to indirectly reflect peripheral oxygen extraction through the following equation: O 2 extraction (%) = D aÀ" v O 2 max arterial O 2 content Â 100 (Mortensen et al. 2005). As a first step, Poole and Musch questioned the validity of our results, especially _ Q max and D aÀ" v O 2 max ; emphasizing the possibility that our values may have been unrealistic. After analysis of the literature on the question, it appears that some studies measured higher values of _ Q max for similar _ VO 2 max and then lower D aÀ" v O 2 max compared to our study (Hagberg et al. 1985;McGuire et al. 2001). For example, Stickland et al. (2004) measured, with the ''gold standard'' direct Fick method, a _ Q of 22.2 L min -1 (19.5 L min -1 in our study) for a _ VO 2 of 2.49 L min -1 (2.51 L min -1 in our study), thereby giving a DavO 2 around 11.2 mL dL -1 (12.7 mL dL -1 in our study).During the study, the subjects trained at 61% of maximal power output (P max ) in the continuous training (CT) modality and they alternated 4 min at low intensity (49% of P max ) with 1 min at 90% of P max during interval training (IT). In our design, CT involved a constant intensity and displayed a constant heart rate. Therefore, we assumed that both _ Q and muscle blood flow would have been relatively constant during the training session and may not have been high enough to elicit significant enhancement of _ Q max and systemic O 2 delivery.We agree that we observed a small elevation in _ Q max and compared to the substantial increase of _ VO 2 max : However, the ratio between D _ Q _ Q max À _ Q rest À Á and D _ VO 2 _ VO 2 max À _ VO 2rest À Á was 6.8 before training and went down to 6.1 after training, both being values similar to those documented in the literature (Taivassalo et al. 2003) and there are in accordance with remarks of Poole and Musch (Poole and Musch 2008).Regarding the error in the determination of _ Q determination and _ VO 2 max pointed out by Poole and Musch, we would like, first, to remind the reader that the multiplication of the mean values is different from the mean of multiplied values. Regarding the training induced improvement of _ VO 2 max ; we have carefully checked all the individual data and we notice that for one subject an error occurred. Taken the new value into account, we get an increase of 21.5% corresponding to a _ VO 2 max of 32.2 mL min -1 kg -1 . In exact details, this improvement in _ VO 2 max was brought about by a...

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confidence: 88%

“…Poole and Musch (Poole and Musch 2008) and we thank them for giving us the opportunity to explain in further details our methodology and interpretations. To clarify the ideas developed in our paper, we would like to go back to some of the definitions related to the key parameters we have used.…”

mentioning

confidence: 99%

Solving the Fick principle using whole body measurements can be used to discriminate ‘‘central’’ and ‘‘peripheral’’ adaptations to training

2008

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“…However, to our knowledge, there have been no reports that higher muscle blood flow was observed in MI patients compared with that in CON. Future studies are needed to examine muscle oxygen perfusion directly during exercise in early after-MI patients because O 2 extraction is affected by O 2 supply itself (26). Furthermore, O 2 extraction is potentially affected by structural (muscle fiber-type composition, capillary bed) and functional (neurohumoral, reflex, or inflammatory) factors in heart failure patients (25).…”

Section: Discussionmentioning

confidence: 99%

Skeletal Muscle Deoxygenation Abnormalities in Early Post-Myocardial Infarction

Takagi

Murase

Kime

et al. 2014

Medicine &Amp; Science in Sports &Amp; Exercise

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“…With the comparison of DCS with con- ventional measures of convective O 2 delivery and mVO 2 , we show that the two approaches are far more similar than they are different. The data also highlight a common misconception of the Fick principle (25,28), namely, that increases in skeletal mVO 2 are almost entirely dependent on convective O 2 delivery, and show instead an equal contribution from diffusive O 2 conductance. Taken together, these data highlight the potential role that DCS can play, both clinically and as a research tool, for extending our pathophysiologic understanding of exercise (in)tolerance across the spectrum of health and disease noninvasively.…”

Section: Discussionmentioning

confidence: 70%

Determinants of skeletal muscle oxygen consumption assessed by near-infrared diffuse correlation spectroscopy during incremental handgrip exercise

Rosenberry

Tucker

Haykowsky

et al. 2019

Journal of Applied Physiology

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Near-infrared diffuse correlation spectroscopy (DCS) is a rapidly evolving optical imaging technique for the assessment of skeletal muscle O2 utilization (mVO2). We compared DCS-derived determinants of mVO2 with conventional measures [blood flow by brachial artery Doppler ultrasound and venous O2 saturation ([Formula: see text])] in eight volunteers at rest and during incremental handgrip exercise. Brachial artery blood flow and DCS-derived blood flow index (BFI) were linearly related (R2 = 0.57) and increased with each workload, whereas [Formula: see text] decreased from 65.3 ± 2.5% (rest) to 39.9 ± 3.0% (light exercise; P < 0.01) with no change thereafter. In contrast, DCS-derived tissue O2 saturation decreased progressively with each incremental stage ( P < 0.01), driven almost entirely by an initial steep rise in deoxyhemoglobin/myoglobin, followed by a linear increase thereafter. Whereas seemingly disparate at first glance, we believe these two approaches provide similar information. Indeed, by plotting the mean convective O2 delivery and diffusive O2 conductance, we show that the initial increase in mVO2 during the transition from rest to exercise was achieved by a greater increase in diffusive O2 conductance versus convective O2 delivery (10-fold vs. 4-fold increase, respectively), explaining the initial decline in [Formula: see text]. In contrast, the increase in mVO2 from light to heavy exercise was achieved by equal increases (1.8-fold) in convective O2 delivery and diffusive O2 conductance, explaining the plateau in [Formula: see text]. That DCS-derived BFI and deoxyhemoglobin/myoglobin (surrogate measure of O2 extraction) share the same general biphasic pattern suggests that both DCS and conventional approaches provide complementary information regarding the determinants of mVO2. NEW & NOTEWORTHY Near-infrared diffuse correlation spectroscopy (DCS) is an emerging optical imaging technique for quantifying skeletal muscle O2 delivery and utilization at the microvascular level. Here, we show that DCS provides complementary insight into the determinants of muscle O2 consumption across a wide range of exercise intensities, further establishing the utility of DCS.

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Solving the Fick principle using whole body measurements does not discriminate “central” and “peripheral” adaptations to training

Cited by 10 publications

References 6 publications

Solving the Fick principle using whole body measurements can be used to discriminate ‘‘central’’ and ‘‘peripheral’’ adaptations to training

Solving the Fick principle using whole body measurements can be used to discriminate ‘‘central’’ and ‘‘peripheral’’ adaptations to training

Skeletal Muscle Deoxygenation Abnormalities in Early Post-Myocardial Infarction

Determinants of skeletal muscle oxygen consumption assessed by near-infrared diffuse correlation spectroscopy during incremental handgrip exercise

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