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ULTIMO FASCICOLOTHE JOURNAL OF SPORTS MEDICINE AND PHYSICAL FITNESS

Rivista di Medicina, Traumatologia e Psicologia dello Sport


Indexed/Abstracted in: Chemical Abstracts, CINAHL, Current Contents/Clinical Medicine, EMBASE, PubMed/MEDLINE, Science Citation Index Expanded (SciSearch), Scopus
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The Journal of Sports Medicine and Physical Fitness 2000 Settembre;40(3):209-16

 ORIGINAL ARTICLES

Is the ven­til­a­to­ry thresh­old coin­ci­dent with max­i­mal fat oxi­da­tion dur­ing sub­max­i­mal exer­cise in wom­en?

Astorino T. A.

Center for Exercise and Applied Human Physiology, University of New Mexico, Albuquerque, NM, USA

Background. The pur­pose of ­this ­study was to ­detect the frac­tion of ­peak oxy­gen con­sump­tion (V.O2peak) ­that elic­its max­i­mal ­rates of fat oxi­da­tion dur­ing sub­max­i­mal tread­mill exer­cise. It was hypoth­e­sized ­that ­this ­point ­would ­appear at a ­work ­rate ­just ­below the ven­til­a­to­ry thresh­old.
Methods. Experimental design: subjects com­plet­ed a pro­to­col requir­ing ­them to exer­cise for 15 min on a tread­mill at six dif­fer­ent work­loads, 25, 40, 55, 65, 75, and 85% V.O2peak, ­over two sep­ar­ate vis­its. Participants: nine ­healthy, mod­er­ate­ly-­trained eumen­or­rhe­ic ­females (age = 28.8±5.99 yrs, V.O2peak = 47.20 ±2.57 ml.kg-1.min-1) vol­un­teered for the ­study. Measures: a one-way ANO­VA ­with repeat­ed meas­ures was ­used to ­test for dif­fer­enc­es ­across exer­cise inten­sities in the meta­bol­ic var­i­ables (i.e. sub­strate oxi­da­tion, ­blood lac­tate con­cen­tra­tion ([La-]), RER, and the con­tri­bu­tion of fat to ­total ener­gy expen­di­ture). Following sig­nif­i­cant F ­ratios, ­post-hoc ­tests ­were ­used to ­detect dif­fer­enc­es ­between the ­means for var­i­ous exer­cise inten­sities.
Results. Exercise at 75% V.O2peak elic­it­ed the great­est ­rate of fat oxi­da­tion (4.75±0.49 ­kcal.min-1), and ­this inten­sity was coin­ci­dent ­with the ven­til­a­to­ry thresh­old (76±7.41% V.O2peak). Moreover, a sig­nif­i­cant dif­fer­ence (t(8) = -3.98, p<0.01) was not­ed ­between the ­mean ven­til­a­to­ry thresh­old and lac­tate thresh­old.
Conclusions. The find­ing ­that a rel­a­tive­ly ­heavy ­work ­rate elic­its the high­est ­rate of fat oxi­da­tion in an ­active, ­female pop­u­la­tion has appli­ca­tion in exer­cise pre­scrip­tion and ­refutes the ­belief ­that low-inten­sity exer­cise is pre­ferred for fat metab­olism.

lingua: Inglese


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