Muscle mass and inspired oxygen influence oxygen extraction at maximal exercise: Role of mitochondrial oxygen affinity

Cardinale, Daniele A.; Larsen, Filip J.; Jensen‐Urstad, Mats; Rullman, Eric; Söndergaard, Hans Peter; Morales-Álamo, David; Ekblom, Björn; Calbet, José A. L.; Boushel, Robert

doi:10.1111/apha.13110

Cited by 39 publications

(107 citation statements)

References 47 publications

(62 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…%iEMG max ) will be determined by the extant fractional O 2 extraction and its interdependence with augmented blood flow (Okushima et al., , ). In addition, mitochondrial activation and O 2 affinity (p50) also alters this point (Cardinale et al., ). Should mitochondrial volume and respiratory capacity be different between muscle groups, this would affect mitochondrial p50 and contribute to the different deoxy[Hb + Mb] patterns observed between muscles.…”

Section: Discussionmentioning

confidence: 99%

“…%iEMG max ) will be determined by the extant fractional O 2 extraction and its interdependence with augmented blood flow (Okushima et al, 2015(Okushima et al, , 2016. In addition, mitochondrial activation and O 2 affinity (p50) also alters this point (Cardinale et al, 2018 At a given submaximal power output, deoxy[Hb + Mb] was greater and S tO 2 lower in the RF muscle for KE compared with CE ( Figure 3).…”

Section: The Relationship Of Nirs Measurements To Muscle Activation Pmentioning

confidence: 99%

See 1 more Smart Citation

Effect of differential muscle activation patterns on muscle deoxygenation and microvascular haemoglobin regulation

Okushima

Poole

Barstow

et al. 2020

Experimental Physiology

View full text Add to dashboard Cite

New Findings What is the central question of this study?Does the presence and extent of heterogeneity in the ratio of O2 delivery to uptake across human muscles relate specifically to different muscle activation patterns? What is the main finding and its importance?During ramp incremental knee‐extension and cycling exercise, the profiles of muscle deoxygenation (deoxy[haemoglobin + myoglobin]) and diffusive O2 potential (total[haemoglobin + myoglobin]) in the vastus lateralis corresponded to different muscle activation strategies. However, this was not the case for the rectus femoris, where muscle activation and deoxygenation profiles were dissociated and might therefore be determined by other structural and/or functional attributes (e.g. arteriolar vascular regulation and control of red blood cell flux). Abstract Near‐infrared spectroscopy has revealed considerable heterogeneity in the ratio of O2 delivery to uptake as identified by disparate deoxygenation {deoxy[haemoglobin + myoglobin] (deoxy[Hb + Mb])} values in the exercising quadriceps. However, whether this represents a recruitment phenomenon or contrasting vascular and metabolic control, as seen among fibre types, has not been established. We used knee‐extension (KE) and cycling (CE) incremental exercise protocols to examine whether differential muscle activation profiles could account for the heterogeneity of deoxy[Hb + Mb] and microvascular haemoconcentration (i.e. total[Hb + Mb]). Using time‐resolved near‐infrared spectroscopy for the quadriceps femoris (vastus lateralis and rectus femoris) during exhaustive ramp exercise in eight participants, we tested the following hypotheses: (i) the deoxy[Hb + Mb] (i.e. fractional O2 extraction) would relate to muscle activation levels across exercise protocols; and (ii) KE would induce greater total[Hb + Mb] (i.e. diffusive O2 potential) at task failure (i.e. peak O2 uptake) than CE irrespective of muscle site. At a given level of muscle activation, as assessed by the relative integrated EMG normalized to maximal voluntary contraction (%iEMGmax), the vastus lateralis deoxy[Hb + Mb] profile was not different between exercise protocols. However, at peak O2 uptake and until 20% iEMGmax for CE, rectus femoris exhibited a lower deoxy[Hb + Mb] (83.2 ± 15.5 versus 98.2 ± 19.4 μm) for KE than for CE (P < 0.05). The total[Hb + Mb] at peak O2 uptake was not different between exercise protocols for either muscle site. These data support the hypothesis that the contrasting patterns of convective and diffusive O2 transport correspond to different muscle activation patterns in vastus lateralis but not rectus femoris. Thus, the differential deoxygenation profiles for rectus femoris across exercise protocols might be dependent upon specific facets of muscle architecture and functional haemodynamic events.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: The Relationship Of Nirs Measurements To Muscle Activation Pmentioning

confidence: 99%

Effect of differential muscle activation patterns on muscle deoxygenation and microvascular haemoglobin regulation

Okushima

Poole

Barstow

et al. 2020

Experimental Physiology

View full text Add to dashboard Cite

show abstract

“…During whole‐body maximal exercise, the oxidative capacity of skeletal muscle exceeds the O 2 delivery, as illustrated by the twofold higher

{\overset{V}{true} normalO}_{2}

per unit of muscle mass during dynamic one‐legged knee extension compared to cycling exercise (approximately 2.5 vs 20 kg active muscle mass, respectively) 10,72 . Therefore, the leg muscles possess an oxidative reserve capacity at

{\overset{V}{true} normalO}_{2max}

during whole‐body exercise, which has frequently been used as an argument to indicate that the large improvements in mitochondrial and capillary networks after endurance training are likely only crucial for improvements in endurance performance and do not affect the limiting factors to

{\overset{V}{true} normalO}_{2max}

83 .…”

Section: The Mechanisms Explaining the Improvements Of O2 Extraction mentioning

confidence: 99%

Contribution of oxygen extraction fraction to maximal oxygen uptake in healthy young men

et al. 2020

View full text Add to dashboard Cite

We analysed the importance of systemic and peripheral arteriovenous O2 difference ( a-normalv¯normalO2 difference and a‐vfO2 difference, respectively) and O2 extraction fraction for maximal oxygen uptake ( trueV˙normalO2max). Fick law of diffusion and the Piiper and Scheid model were applied to investigate whether diffusion versus perfusion limitations vary with trueV˙normalO2max. Articles (n = 17) publishing individual data (n = 154) on trueV˙normalO2max, maximal cardiac output ( Q˙max; indicator‐dilution or the Fick method), a-normalv¯normalO2 difference (catheters or the Fick equation) and systemic O2 extraction fraction were identified. For the peripheral responses, group‐mean data (articles: n = 27; subjects: n = 234) on leg blood flow (LBF; thermodilution), a‐vfO2 difference and O2 extraction fraction (arterial and femoral venous catheters) were obtained. Q˙max and two‐LBF increased linearly by 4.9‐6.0 L · min–1 per 1 L · min–1 increase in trueV˙normalO2max (R2 = .73 and R2 = .67, respectively; both P < .001). The a-normalv¯normalO2 difference increased from 118‐168 mL · L–1 from a trueV˙normalO2max of 2‐4.5 L · min–1 followed by a reduction (second‐order polynomial: R2 = .27). After accounting for a hypoxemia‐induced decrease in arterial O2 content with increasing trueV˙normalO2max (R2 = .17; P < .001), systemic O2 extraction fraction increased up to ~90% ( trueV˙normalO2max: 4.5 L · min–1) with no further change (exponential decay model: R2 = .42). Likewise, leg O2 extraction fraction increased with trueV˙normalO2max to approach a maximal value of ~90‐95% (R2 = .83). Muscle O2 diffusing capacity and the equilibration index Y increased linearly with trueV˙normalO2max (R2 = .77 and R2 = .31, respectively; both P < .01), reflecting decreasing O2 diffusional limitations and accentuating O2 delivery limitations. In conclusion, although O2 delivery is the main limiting factor to trueV˙normalO2max, enhanced O2 extraction fraction (≥90%) contributes to the remarkably high trueV˙normalO2max in endurance‐trained individuals.

show abstract

“…2-4 Therefore, a more than twofold larger O 2 delivery per unit muscle mass is observed during 1L-KE compared with cycling (500 vs 240 mL•min −1 •kg −1 muscle , respectively). 5 Despite this, the mass-specific V O 2 is only ~70% higher due to a substantially lower leg O 2 extraction during 1L-KE. 5 The decreased O 2 extraction may be caused by fully activated mitochondria respiring near their maximal rate, 5,6 a condition that may restrict further O 2 extraction and O 2 diffusion from the blood to cytochrome-c-oxidase.…”

Section: Introductionmentioning

confidence: 98%

Increased oxygen extraction and mitochondrial protein expression after small muscle mass endurance training

Skattebo

Capelli

Rud

et al. 2020

Scandinavian Med Sci Sports

View full text Add to dashboard Cite

When exercising with a small muscle mass, the mass‐specific O2 delivery exceeds the muscle oxidative capacity resulting in a lower O2 extraction compared with whole‐body exercise. We elevated the muscle oxidative capacity and tested its impact on O2 extraction during small muscle mass exercise. Nine individuals conducted six weeks of one‐legged knee extension (1L‐KE) endurance training. After training, the trained leg (TL) displayed 45% higher citrate synthase and COX‐IV protein content in vastus lateralis and 15%‐22% higher pulmonary oxygen uptake ( trueV˙normalO2peak) and peak power output ( normalW˙peak) during 1L‐KE than the control leg (CON; all P < .05). Leg O2 extraction (catheters) and blood flow (ultrasound Doppler) were measured while both legs exercised simultaneously during 2L‐KE at the same submaximal power outputs (real‐time feedback‐controlled). TL displayed higher O2 extraction than CON (main effect: 1.7 ± 1.6% points; P = .010; 40%‐83% of normalW˙peak) with the largest between‐leg difference at 83% of normalW˙peak (O2 extraction: 3.2 ± 2.2% points; arteriovenous O2 difference: 7.1 ± 4.8 mL· L−1; P < .001). At 83% of normalW˙peak, muscle O2 conductance (DMO2; Fick law of diffusion) and the equilibration index Y were higher in TL (P < .01), indicating reduced diffusion limitations. The between‐leg difference in O2 extraction correlated with the between‐leg ratio of citrate synthase and COX‐IV (r = .72‐.73; P = .03), but not with the difference in the capillary‐to‐fiber ratio (P = .965). In conclusion, endurance training improves O2 extraction during small muscle mass exercise by elevating the muscle oxidative capacity and the recruitment of DMO2, especially evident during high‐intensity exercise exploiting a larger fraction of the muscle oxidative capacity.

show abstract

Muscle mass and inspired oxygen influence oxygen extraction at maximal exercise: Role of mitochondrial oxygen affinity

Abstract: O extraction varies with mitochondrial respiration rate, p50 and O delivery. Mitochondrial excess capacity maintains a low p50 which enhances O diffusion from microvessels to mitochondria during exercise.

Cited by 39 publications

References 47 publications

Effect of differential muscle activation patterns on muscle deoxygenation and microvascular haemoglobin regulation

Effect of differential muscle activation patterns on muscle deoxygenation and microvascular haemoglobin regulation

Contribution of oxygen extraction fraction to maximal oxygen uptake in healthy young men

Increased oxygen extraction and mitochondrial protein expression after small muscle mass endurance training

Contact Info

Product

Resources

About