Original articles   

The Journal of Sports Medicine and Physical Fitness 2000 March;40(1):11-6

Copyright © 2002 EDIZIONI MINERVA MEDICA

lingua: Inglese

Kinetics of oxygen uptake during decremental ramp exercise

Yano T., Yunoki T., Horiuchi M.

From the Laboratory of Human Movement Science Faculty of Education, Hokkaido University, Japan

Back­ground. The pur­pose of the ­present ­study was to ­examine the ­kinetics of ­oxygen ­uptake (V.O2) ­during decre­mental ­ramp exer­cises ­after incre­mental ­ramp exer­cise ­above the anaer­obic ­threshold.
­Methods. Tri­angle exer­cise con­sisting of incre­mental and decre­mental exer­cises, and trap­e­zoid exer­cise in ­which a con­stant ­load was ­inserted ­between incre­mental and decre­mental exer­cises ­were car­ried out.
­Results. ­Blood lac­tate (La) ­increased in incre­mental ­phases ­during tri­angle and trap­e­zoid exer­cises, and ­showed a fur­ther ­increase at con­stant ­work ­during trap­e­zoid exer­cise. It sig­nif­i­cantly ­decreased ­during decre­mental exer­cise. ­Initial V.O2 ­level ­during decre­mental exer­cise was sig­nif­i­cantly ­higher in trap­e­zoi­d ex­er­cise ­than in tri­angle exer­cise. The V.O2 ­level ­then expo­nen­tially ­decreased and ­later ­showed a ­linear ­decrease ­during ­both exer­cises. ­These V.O2 ­kinetics ­were ­expressed by an approx­i­mate equa­tion. The ­time con­stant ­expressing the expo­nen­tial ­manner was ­about one ­minute on ­average in ­both exer­cises. The ­slope of the lin­e­arly ­decreasing ­phase of V.O2 was sig­nif­i­cantly ­related to La at 100 ­watts ­during the decre­mental exer­cise.
Con­clu­sions. V.O2 ­kinetics ­during decre­mental exer­cise ­after incre­mental exer­cise ­above the anaer­obic ­threshold con­sists of at ­least ­three com­po­nents: ­initial ­level, expo­nen­tially ­decreasing ­phase, and lin­e­arly ­decreasing ­phase.