Modeling V̇<scp>o</scp><sub>2</sub> on-kinetics based on intensity-dependent delayed adjustment and loss of efficiency (DALE)

Gløersen, Øyvind; Colosio, Alessandro L.; Boone, Jan; Dysthe, Dag Kristian; Malthe‐Sørenssen, Anders; Capelli, Carlo; Pogliaghi, Silvia

doi:10.1152/japplphysiol.00570.2021

Cited by 5 publications

(2 citation statements)

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“…The extent to which the continuous accumulation of oxygen deficits with time, particularly at the 4-laps condition, can be attributed to such a loss of efficiency, or other aspects of the model, is hard to assess. Recent advances within modelling of VO 2 -kinetics include time-dependent energy conversion efficiencies (Gløersen et al 2022). Further development of this methodology might elucidate this aspect.…”

Section: Methodological Considerationsmentioning

confidence: 99%

The influence of race duration on oxygen demand, uptake and deficit in competitive cross-country skiers

Gløersen,

Viken,

Lund-Hansen

et al. 2024

Eur J Appl Physiol

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Purpose To measure oxygen demand, uptake, and deficits in competitive cross-country skiers during outdoor roller skiing at different competition durations, ranging from the endurance domain to the sprint domain. Methods Ten competitive cross-country skiers (6 males; $$\dot{\text{V}}$$ V ˙ O2max 78 ± 3 and 4 females; $$\dot{\text{V}}$$ V ˙ O2max 62 ± 3 mL∙kg−1∙min−1) raced time trials consisting of 1, 2, and 4 laps in a 1.6 km racecourse in a randomized order with 35 min recovery in-between. Oxygen uptake was measured using a wearable metabolic system while oxygen demand was estimated from kinematic data (GPS and IMU) and an athlete-specific model of skiing economy. Skiing economy and $$\dot{\text{V}}$$ V ˙ O2max was established on a separate test day using six submaximal constant-load trials at different speeds and inclines, and one maximal-effort trial on a roller-skiing treadmill. Results Average oxygen demand was 112 ± 8%, 103 ± 7% and 98 ± 7% of $$\dot{\text{V}}$$ V ˙ O2max during the 1 (3:37 ± 0:20 m:ss), 2 (7:36 ± 0:38 m:ss) and 4 (15:43 ± 1:26 m:ss) lap time trials, respectively, and appeared to follow an inverse relationship with time-trial duration. Average oxygen uptake was unaffected by race length (86 ± 5%, 86 ± 5%, and 86 ± 7% of $$\dot{\text{V}}$$ V ˙ O2max, respectively). Accumulated oxygen deficit at the end of each time trial was 85 ± 13, 106 ± 32 and 158 ± 62 mL∙kg−1, while oxygen deficits per work bout was 23 ± 3, 18 ± 3 and 16 ± 3 mL∙kg−1 for the 1, 2, and 4-lap time trials, respectively. Conclusion Elite cross-country skiers adjust their pacing strategies from attaining relatively small oxygen deficits per work bout in the endurance domain, to larger deficits in the sprint domain. This indicates a shift in strategy from prioritizing stable work-economy and rate-of-recovery in the endurance domain, to maximizing power output in the sprint domain.

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Section: Methodological Considerationsmentioning

confidence: 99%

The influence of race duration on oxygen demand, uptake and deficit in competitive cross-country skiers

Gløersen,

Viken,

Lund-Hansen

et al. 2024

Eur J Appl Physiol

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“…Briefly, the fundamental O 2 amplitude represents the initial target amplitude, or the anticipated steady-state response that can only be achieved during moderate-intensity exercise. The subsequent emergence of the O 2 slow component represents an elevated O 2 requirement in response to neuromuscular fatigue [ 117 – 119 ] (although for an alternative interpretation, see [ 120 , 121 ]). One factor that drives O 2 above the anticipated steady state during heavy- and severe-intensity exercise is thought to be the recruitment of additional motor units and the resulting metabolism of the fibres associated with them [ 34 ].…”

Section: Mechanisms Underpinning the Priming Effectmentioning

confidence: 99%

How Priming Exercise Affects Oxygen Uptake Kinetics: From Underpinning Mechanisms to Endurance Performance

Goulding

Wüst

2023

Sports Med

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The observation that prior heavy or severe-intensity exercise speeds overall oxygen uptake ($$\dot{V}$$ V ˙ O2) kinetics, termed the “priming effect”, has garnered significant research attention and its underpinning mechanisms have been hotly debated. In the first part of this review, the evidence for and against (1) lactic acidosis, (2) increased muscle temperature, (3) O2 delivery, (4) altered motor unit recruitment patterns and (5) enhanced intracellular O2 utilisation in underpinning the priming effect is discussed. Lactic acidosis and increased muscle temperature are most likely not key determinants of the priming effect. Whilst priming increases muscle O2 delivery, many studies have demonstrated that an increased muscle O2 delivery is not a prerequisite for the priming effect. Motor unit recruitment patterns are altered by prior exercise, and these alterations are consistent with some of the observed changes in $$\dot{V}$$ V ˙ O2 kinetics in humans. Enhancements in intracellular O2 utilisation likely play a central role in mediating the priming effect, probably related to elevated mitochondrial calcium levels and parallel activation of mitochondrial enzymes at the onset of the second bout. In the latter portion of the review, the implications of priming on the parameters of the power–duration relationship are discussed. The effect of priming on subsequent endurance performance depends critically upon which phases of the $$\dot{V}$$ V ˙ O2 response are altered. A reduced $$\dot{V}$$ V ˙ O2 slow component or increased fundamental phase amplitude tend to increase the work performable above critical power (i.e. W´), whereas a reduction in the fundamental phase time constant following priming results in an increased critical power.

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Comparing parameter-reduction methods on a biophysical model of an auditory hair cell

Marcinik,

Toderi,

Bozovic

2024

Phys. Rev. Research

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Biophysical models describing complex cellular phenomena typically include systems of nonlinear differential equations with many free parameters. While experimental measurements can fix some parameters, those describing internal cellular processes frequently remain inaccessible. Hence, a proliferation of free parameters risks overfitting the data, limiting the model's predictive power. In this study, we develop systematic methods, applying statistical analysis and dynamical-systems theory, to reduce parameter count in a biophysical model. We demonstrate our techniques on a five-variable computational model designed to describe active, mechanical motility of auditory hair cells. Specifically, we use two statistical measures, the total-effect and PAWN indices, to rank each free parameter by its influence on selected, core properties of the model. With the resulting ranking, we fix most of the less influential parameters, yielding a five-parameter model with refined predictive power. We validate the theoretical model with experimental recordings of active hair-bundle motility, specifically by using Akaike and Bayesian information criteria after obtaining maximum-likelihood fits. As a result, we determine the system's most influential parameters, which illuminate the key biophysical elements of the cell's overall features. Even though we demonstrate with a concrete example, our techniques provide a general framework, applicable to other biophysical systems. Published by the American Physical Society 2024

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Modeling V̇o₂ on-kinetics based on intensity-dependent delayed adjustment and loss of efficiency (DALE)

Cited by 5 publications

References 50 publications

The influence of race duration on oxygen demand, uptake and deficit in competitive cross-country skiers

The influence of race duration on oxygen demand, uptake and deficit in competitive cross-country skiers

How Priming Exercise Affects Oxygen Uptake Kinetics: From Underpinning Mechanisms to Endurance Performance

Comparing parameter-reduction methods on a biophysical model of an auditory hair cell

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Modeling V̇o2 on-kinetics based on intensity-dependent delayed adjustment and loss of efficiency (DALE)

Cited by 5 publications

References 50 publications

The influence of race duration on oxygen demand, uptake and deficit in competitive cross-country skiers

The influence of race duration on oxygen demand, uptake and deficit in competitive cross-country skiers

How Priming Exercise Affects Oxygen Uptake Kinetics: From Underpinning Mechanisms to Endurance Performance

Comparing parameter-reduction methods on a biophysical model of an auditory hair cell

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Modeling V̇o₂ on-kinetics based on intensity-dependent delayed adjustment and loss of efficiency (DALE)