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Medicine & Science in Sports & Exercise: November 1994
Symposium: Mechanistic Basis of the Slow Component of JOURNAL/mespex/04.02/00005768-199411000-00008/ENTITY_OV0312/v/2017-07-20T222430Z/r/image-pngO2 Kinetics During Heavy Exercise: PDF Only


For constant-load, heavy exercise (i.e., above the lactate threshold (TLac.)), a slow component of oxygen uptake (JOURNAL/mespex/04.02/00005768-199411000-00008/ENTITY_OV0312/v/2017-07-20T222430Z/r/image-pngO2) is observed. Endurance training reduces the magnitude of the slow component and, hence, end-exercise JOURNAL/mespex/04.02/00005768-199411000-00008/ENTITY_OV0312/v/2017-07-20T222430Z/r/image-pngO2. Reductions in exercise JOURNAL/mespex/04.02/00005768-199411000-00008/ENTITY_OV0312/v/2017-07-20T222430Z/r/image-pngO2 have been reported after 7–8 wk of training; unpublished observations suggest that the JOURNAL/mespex/04.02/00005768-199411000-00008/ENTITY_OV0312/v/2017-07-20T222430Z/r/image-pngO2 slow component may be attenuated after just 2 wk of training. A minimum training intensity for eliciting reductions in constant-load exercise JOURNAL/mespex/04.02/00005768-199411000-00008/ENTITY_OV0312/v/2017-07-20T222430Z/r/image-pngO2 has not been established; however, in the elderly, training at an intensity below TLac resulted in similar reductions in exercise JOURNAL/mespex/04.02/00005768-199411000-00008/ENTITY_OV0312/v/2017-07-20T222430Z/r/image-pngO2 as did training above TLac. Mechanisms responsible for the reduced slow component of JOURNAL/mespex/04.02/00005768-199411000-00008/ENTITY_OV0312/v/2017-07-20T222430Z/r/image-pngO2 after training remain to be firmly established. Evidence both for and against blood lactate concentration ([L−]) as a mediator of the slow component has been published; high correlations between [L−] and the slow component, and between the training-induced reductions in these variables, appear to be more coincidental than causal. Decreased pulmonary ventilation after training may account for between 14% and 30% of the reduction in the slow component of JOURNAL/mespex/04.02/00005768-199411000-00008/ENTITY_OV0312/v/2017-07-20T222430Z/r/image-pngO2. Epinephrine infusion does not augment exercise JOURNAL/mespex/04.02/00005768-199411000-00008/ENTITY_OV0312/v/2017-07-20T222430Z/r/image-pngO2, nor does β-adrenergic blockade diminish the magnitude of the slow component of JOURNAL/mespex/04.02/00005768-199411000-00008/ENTITY_OV0312/v/2017-07-20T222430Z/r/image-pngO2.

©1994The American College of Sports Medicine