Changes in VO2 Kinetics After Elevated Baseline Do Not Necessarily Reflect Alterations in Muscle Force Production in Both Sexes

Salvador, Paulo Cesar do Nascimento; Schäfer, Lisa; Grassi, Bruno; Guglielmo, Luiz Guilherme Antonacci; Denadai, Benedito Sérgio

doi:10.3389/fphys.2019.00471

Cited by 4 publications

(10 citation statements)

References 51 publications

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“…First, although the present results on NM alterations are consistent with existing literature (12) and seem to go in same direction across muscles (i.e., with women appearing less fatigued), differences are probably not strong enough to differently alter Cr between men and women. Second, as mentioned in the introduction, contrary to popular hypothesis, NM fatigue is possibly not as strongly related to oxygen uptake kinetics (21–24) and therefore energy Cr. However, a type II error cannot be ruled out given that out of the 18 matched pairs who finished the race, only 13 were able to perform the Cr POST evaluations (7 pairs in SHORT and 6 in LONG).…”

Section: Discussionmentioning

confidence: 77%

“…Second, as mentioned in the introduction, contrary to popular hypothesis, NM fatigue is possibly not as strongly related to oxygen uptake kinetics (21)(22)(23)(24) and therefore energy cost of running. However, a type II error cannot be ruled out given that out of the 18 matched pairs who finished the race, only 13 were able to perform the Cr POST evaluations (7 pairs in SHORT and 6 in LONG).…”

Section: Sex Differences In Energy Cost Of Runningmentioning

confidence: 79%

“…As such, it is possible that attenuated muscle fatigue in females could reduce the compensatory increase in motor unit recruitment and thus V ̇O2 demand. However, it should be noted that conflicting evidence exists surrounding the effects of muscle fatigue on changes in V ̇O2, with some studies reporting no interaction between these variables (21)(22)(23)(24). In addition to Glace, et al (15) only two other studies have to the best of our knowledge examined sex difference on Cr change with fatigue and observed similar changes in males and females: one following a 1-h run at marathon pace (25) and another one following a 5-km run at 80-85% of maximal oxygen uptake (V ̇O2max) (26).…”

Section: Introductionmentioning

confidence: 99%

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Sex Differences in Neuromuscular Fatigue and Changes in Cost of Running after Mountain Trail Races of Various Distances

Besson

Parent

Brownstein

et al. 2021

Medicine &Amp; Science in Sports &Amp; Exercise

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Introduction: Females have been shown to experience less neuromuscular fatigue than males in knee extensors (KE) and less peripheral fatigue in plantar flexors (PF) following ultra-trail running, but it is unknown if these differences exist for shorter trail running races and whether this may impact running economy. The purpose of this study was to characterize sex differences in fatigability over a range of running distances and to examine possible differences in the postrace alteration of the cost of running (Cr).Methods: Eighteen pairs of males and females were matched by performance after completing different races ranging from 40 to 171 km, divided into SHORT vs LONG races (< 60 and > 100 km, respectively). NM function and Cr were tested before and after each race. NM function was evaluated on both KE and PF with voluntary and evoked contractions using electrical nerve (KE and PF) and transcranial magnetic (KE) stimulation. Oxygen uptake, respiratory exchange ratio and ventilation were measured on a treadmill and used to calculate Cr.Results: Compared to males, females displayed a smaller decrease in maximal strength in KE (−36% vs −27%, respectively, p < 0.01), independent of race distance. In SHORT only, females displayed less peripheral fatigue in PF compared to males (Δ peak twitch: −10% vs −24%, respectively, p < 0.05). Cr increased similarly in males and females.Conclusion: Females experience less neuromuscular fatigue than men following both 'classic' and 'extreme' prolonged running exercises but this does not impact the degradation of the energy cost of running.

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Section: Discussionmentioning

confidence: 77%

Section: Sex Differences In Energy Cost Of Runningmentioning

confidence: 79%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Sex Differences in Neuromuscular Fatigue and Changes in Cost of Running after Mountain Trail Races of Various Distances

Besson

Parent

Brownstein

et al. 2021

Medicine &Amp; Science in Sports &Amp; Exercise

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“…However, other authors have demonstrated contrary evidence regarding the relationship between VO 2 kinetics and locomotor muscle fatigue (de Souza et al, 2016;Hopker et al, 2016;Thistlethwaite et al, 2008). Do Nascimento Salvador et al (2018, 2019 have shown that changes in VO 2 sc and/or τ did not reflect alterations in muscle force production and fatigue during very heavy cycling in healthy male and female subjects.…”

Section: New Findingsmentioning

confidence: 99%

“…Do Nascimento Salvador et al. (2018, 2019) have shown that changes in

{\dot{V}}_{{{\rm{O}}}_{\rm{2}}{\rm{sc}}}

and/or τ did not reflect alterations in muscle force production and fatigue during very heavy cycling in healthy male and female subjects.…”

Section: Introductionmentioning

confidence: 99%

Energy metabolism and muscle activation heterogeneity explain V̇O2${\dot{V}}_{{{\rm{O}}}_{\rm{2}}}$ slow component and muscle fatigue of cycling at different intensities

Salvador

Nascimento

Antunes

et al. 2023

Experimental Physiology

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New Findings What is the central question of this study?What are the physiological mechanisms underlying muscle fatigue and the increase in the O2 cost per unit of work during high‐intensity exercise? What is the main finding and its importance?Muscle fatigue happens before, and does not explain, the trueV̇O2${\dot{V}}_{{{\rm{O}}}_{\rm{2}}}$ slow component (trueV̇normalO2sc${\dot{V}}_{{{\rm{O}}}_{\rm{2}}{\rm{sc}}}$), but they share the same origin. Muscle activation heterogeneity is associated with muscle fatigue and trueV̇normalO2sc${\dot{V}}_{{{\rm{O}}}_{\rm{2}}{\rm{sc}}}$. Knowing this may improve training prescriptions for healthy people leading to improved public health outcomes. Abstract This study aimed to explain the trueV̇O2${\dot{V}}_{{{\rm{O}}}_{\rm{2}}}$ slow component (trueV̇normalO2sc${\dot{V}}_{{{\rm{O}}}_{\rm{2}}{\rm{sc}}}$) and muscle fatigue during cycling at different intensities. The muscle fatigue of 16 participants was determined through maximal isokinetic effort lasting 3 s during constant work rate bouts of moderate (MOD), heavy (HVY) and very heavy intensity (VHI) exercise. Breath‐by‐breath trueV̇O2${\dot{V}}_{{{\rm{O}}}_{\rm{2}}}$, near‐infrared spectroscopy signals and EMG activity were analysed (thigh muscles). trueV̇normalO2sc${\dot{V}}_{{{\rm{O}}}_{\rm{2}}{\rm{sc}}}$ was higher during VHI exercise (∼70% vs. ∼28% of trueV̇O2${\dot{V}}_{{{\rm{O}}}_{\rm{2}}}$ reserve in HVY). The deoxygenated haemoglobin final value during VHI exercise was higher than during HVY and MOD exercise (∼90% of HHb physiological normalization, vs. ∼82% HVY and ∼45% MOD). The muscle fatigue was greater after VHI exercise (∼22% vs. HVY ∼5%). There was no muscle fatigue after MOD exercise. The greatest magnitude of muscle fatigue occurred within 2 min (VHI ∼17%; HVY ∼9%), after which it stabilized. No significant relationship between trueV̇normalO2sc${\dot{V}}_{{{\rm{O}}}_{\rm{2}}{\rm{sc}}}$ and muscle force production was observed. The τ of muscle trueV̇O2${\dot{V}}_{{{\rm{O}}}_{\rm{2}}}$ was significantly related (R2 = 0.47) with torque decrease for VHI. Type I and II muscle fibre recruitment mainly in the rectus femoris moderately explained the muscle fatigue (R2 = 0.30 and 0.31, respectively) and the trueV̇normalO2sc${\dot{V}}_{{{\rm{O}}}_{\rm{2}}{\rm{sc}}}$ (R2 = 0.39 and 0.27, respectively). The trueV̇normalO2sc${\dot{V}}_{{{\rm{O}}}_{\rm{2}}{\rm{sc}}}$ is also partially explained by blood lactate accumulation (R2 = 0.42). In conclusion muscle fatigue and O2 cost seem to share the same physiological cause linked with a decrease in the muscle trueV̇O2${\dot{V}}_{{{\rm{O}}}_{\rm{2}}}$ and a change in lactate accumulation. Muscle fatigue and trueV̇normalO2sc${\dot{V}}_{{{\rm{O}}}_{\rm{2}}{\rm{sc}}}$ are associated with muscle activation heterogeneity and metabolism of different muscles activated during cycling.

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No sex differences in oxygen uptake or extraction kinetics in the moderate or heavy exercise intensity domains

Solleiro Pons,

Bernert,

Hume

et al. 2023

Preprint

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The integrative response to exercise differs between sexes, with oxidative energy provision purported as a potential mechanism. However, there is a lack of systematic investigation into the kinetics of oxygen uptake (V̇O2) and extraction (HHb+Mb) during exercise in both sexes. Sixteen young adults (8 females, age: 27±5 years) completed three experimental visits. Incremental exercise testing was performed to obtain lactate threshold and V̇O2peak. Subsequent visits involved three six-minute cycling bouts at 80% of lactate threshold and one 30-minute bout at a work rate 30% between the lactate threshold and maximal ramp test power. Pulmonary gas exchange and near-infrared spectroscopy continuously sampled V̇O2 and HHb+Mb, respectively. The mean of six moderate and two heavy intensity transitions were modelled with mono-exponential curves to quantify the phase II response to exercise. Slow component amplitudes were also quantified for the heavy intensity domain. Males and females demonstrated similar relative V̇O2peak values (46.2±6.6 vs 40.5±6.7 ml.kg-1.min-1, p=0.111), with males achieving ~30% greater power outputs (p=0.002). In both the moderate and heavy intensity domains, the relative amplitude of the phase II transition was similar between sexes for V̇O2 (p≥0.179) and HHb+Mb (p≥0.193). Similarly, there were no sex differences in the time constants for V̇O2 (p≥0.385) or HHb+Mb (p≥0.274). In the heavy intensity domain, neither V̇O2 (p≥0.686) or HHb+Mb (p≥0.432) slow component amplitudes were different between sexes. The oxidative response to moderate and heavy intensity exercise did not differ between males and females, suggesting both sexes experience similar degrees of bioenergetic stress during intensity-matched exercise.

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Changes in VO2 Kinetics After Elevated Baseline Do Not Necessarily Reflect Alterations in Muscle Force Production in Both Sexes

Cited by 4 publications

References 51 publications

Sex Differences in Neuromuscular Fatigue and Changes in Cost of Running after Mountain Trail Races of Various Distances

Sex Differences in Neuromuscular Fatigue and Changes in Cost of Running after Mountain Trail Races of Various Distances

Energy metabolism and muscle activation heterogeneity explain V̇O2${\dot{V}}_{{{\rm{O}}}_{\rm{2}}}$ slow component and muscle fatigue of cycling at different intensities

No sex differences in oxygen uptake or extraction kinetics in the moderate or heavy exercise intensity domains

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