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Medicine & Science in Sports & Exercise:
Symposium: Mechanistic Basis of the Slow Component of [latin capital V with dot above]O2 Kinetics During Heavy Exercise: PDF Only

Role of exercising muscle in slow component of [latin capital V with dot above]O2.

POOLE, DAVID C.

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Abstract

This paper: 1) Reviews evidence for the location of the slow component of [latin capital V with dot above]O2 kinetics either within the exercising limbs or alternatively at some site in the rest of the body, e.g., ventilatory, cardiac or accessory muscles. 2) Presents evidence in support of both the fast and slow components (i.e., <3 min and >3 min from exercise onset, respectively) of the exercise [latin capital V with dot above]O2 response residing predominantly in the exercising muscle. For a pulmonary [latin capital V with dot above]O2 slow component in excess of 600 ml O2[middle dot]min-1, more than 80% could be attributed to an augmented [latin capital V with dot above]O2 across the exercising limbs. 3) Assesses the potential for the lactate ion per se to exert a metabolic stimulatory effect in exercising muscle in the absence of the potentially confounding influences of changes in muscle temperature, H+, blood flow or O2 delivery. Within the surgically isolated, electrically stimulated canine gastrocnemius, square wave infusions that increased arterial blood [lactate] by ~10 mM and intramuscular [lactate] to in excess of 9 mM did not increase muscle [latin capital V with dot above]O2. In summary, these investigations demonstrate that the exercising muscle is the predominant site of the [latin capital V with dot above]O2 slow component. However, despite the close temporal association between changes in blood lactate and [latin capital V with dot above]O2 during intense exercise, lactate itself does not mandate an additional [latin capital V with dot above]O2 demand in exercising dog muscle.

(C)1994The American College of Sports Medicine

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