Muscle fiber recruitment and the slow component of O2 uptake: constant work rate vs. all-out sprint exercise.

@article{Vanhatalo2011MuscleFR,
  title={Muscle fiber recruitment and the slow component of O2 uptake: constant work rate vs. all-out sprint exercise.},
  author={Anni Vanhatalo and David C. Poole and Fred J. DiMenna and Stephen J Bailey and Andrew M. Jones},
  journal={American journal of physiology. Regulatory, integrative and comparative physiology},
  year={2011},
  volume={300 3},
  pages={
          R700-7
        }
}
The slow component of pulmonary O(2) uptake (Vo(2)) during constant work rate (CWR) high-intensity exercise has been attributed to the progressive recruitment of (type II) muscle fibers. We tested the following hypotheses: 1) the Vo(2) slow component gain would be greater in a 3-min all-out cycle test than in a work-matched CWR test, and 2) the all-out test would be associated with a progressive decline, and the CWR test with a progressive increase, in muscle activation, as estimated from the… 

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References

SHOWING 1-10 OF 73 REFERENCES

Influence of muscle fiber type and pedal frequency on oxygen uptake kinetics of heavy exercise.

TLDR
The hypothesis that the amplitude of the additional slow component of O2 uptake (VO2) during heavy exercise is correlated with the percentage of type II (fast-twitch) fibers in the contracting muscles is tested is tested and it is concluded that fiber type distribution significantly affects both the fast and slow components of VO2 duringheavy exercise.

Progressive recruitment of muscle fibers is not necessary for the slow component of VO2 kinetics.

TLDR
A progressive recruitment of muscle fibers may not be necessary for the development of the slow component of VO2 kinetics, which may be caused by the metabolic factors that induce muscle fatigue and, as a consequence, reduce the efficiency of muscle contractions.

Is the VO2 slow component dependent on progressive recruitment of fast-twitch fibers in trained runners?

TLDR
Results suggest a progression in the average frequency of the motor unit discharge toward the high frequencies, which coheres with the hypothesis of the progressive recruitment of fast-twitch fibers during the VO2 slow component.

Oxygen uptake kinetics during moderate, heavy and severe intensity ‘submaximal’ exercise in humans: the influence of muscle fibre type and capillarisation

TLDR
It is demonstrated that muscle fibre type is significantly related to both the speed and the amplitudes of the .VO(2) response at the onset of constant-load sub-maximal exercise.

The slow component of O2 uptake is not accompanied by changes in muscle EMG during repeated bouts of heavy exercise in humans

TLDR
These data are consistent with the view that the increased O2 cost associated with performing heavy exercise is coupled with a progressive increase in ATP requirements of the already recruited motor units rather than to changes in the recruitment pattern of slow versus fast‐twitch motor units.

Thigh muscle activation distribution and pulmonary VO2 kinetics during moderate, heavy, and very heavy intensity cycling exercise in humans.

TLDR
Data are consistent with the notion that the Vo(2) slow component is an expression of progressive muscle recruitment during supra-LT exercise.

Muscle activation and the slow component rise in oxygen uptake during cycling.

TLDR
The results support the hypothesis that during constant-rate exercise at intensities above lactate threshold, progressively greater use of fast-twitch motor units increases energy demand and causes concomitant progressive increases in VO2 and lactate.

Oxygen uptake kinetics during two bouts of heavy cycling separated by fatiguing sprint exercise in humans.

TLDR
Vo (2) and Vco(2) kinetic responses to heavy exercise were markedly altered by prior multiple sprint exercises.

A prior bout of contractions speeds VO2 and blood flow on-kinetics and reduces the VO2 slow-component amplitude in canine skeletal muscle contracting in situ.

TLDR
It is suggested that better matching of O2 delivery to VO2 speeds Vo(2) on-kinetics at this metabolic rate, but do not eliminate a potential role for enhanced metabolic activation.

Effects of prior heavy exercise on VO(2) kinetics during heavy exercise are related to changes in muscle activity.

TLDR
The results of the present study indicate that the increased primary VO(2) amplitude observed during the second of two bouts of heavy exercise is related to a greater recruitment of motor units at the onset of exercise.
...