title: Effect of work:rest cycle duration on [Formula: see text] fluctuations during intermittent exercise.
abstract: The succession of on-transient phases that induce a repetition of metabolic changes is a possible mechanism responsible for the greater response to intermittent training (IT). The objective of this study was to quantify [Formula: see text] fluctuations during intermittent exercise characterised by the same work:rest ratio, but different durations and identify which duration leads to the greatest fluctuations. Ten participants (24 ± 5 years; [Formula: see text]: 42 ± 7 mL·min-1·kg-1) performed (1) an incremental test to exhaustion to determine peak work rate (WRpeak) and oxygen uptake ([Formula: see text]), (2), and three 1 h intermittent exercises alternating work period at 70% WRpeakwith passive recovery period of different 1:1 work:recovery duty cycles (30 s:30 s, 60 s:60 s, 120 s:120 s). [Formula: see text] response analysis revealed differences in the fluctuations across the intermittent conditions despite an identical total energy expenditure. The sum of the cycle's nadir-to-peak [Formula: see text] differences (ΣΔ[Formula: see text]) and the oxygen fluctuation index (OFI) were both greater in the 60 s:60 s condition (ΣΔ[Formula: see text]: +38% ± 13% and +19% ± 18% vs. 120 s:120 s and 30 s:30 s, P < 0.05; OFI: +41% ± 29% and +67% ± 62% vs. 120 s:120 s and 30:30 s, P < 0.05). [Formula: see text] fluctuation analysis was successful in identifying the intermittent condition associated with the greatest disturbances: the 60 s:60 s duty cycle induces more [Formula: see text] fluctuations. The present findings also demonstrate that the selection of the duty cycle duration for submaximal intermittent exercise (70% of WRpeak) prescription is of interest to produce high [Formula: see text] fluctuations.
authors.affiliation: a University of Lille, EA 7369 - URePSSS - Unité de Recherche Pluridisciplinaire Sport Santé Société , F-59000 Lille , France.
authors.forename: Adrien
authors.initials: A
authors.lastname: Combes
authors.affiliation: b Centre for Sport Exercise Science and Medicine (SESAME) , University of Brighton , Eastbourne , UK.
authors.forename: Jeanne
authors.initials: J
authors.lastname: Dekerle
authors.affiliation: a University of Lille, EA 7369 - URePSSS - Unité de Recherche Pluridisciplinaire Sport Santé Société , F-59000 Lille , France.
authors.forename: Valérie
authors.initials: V
authors.lastname: Bougault
authors.affiliation: a University of Lille, EA 7369 - URePSSS - Unité de Recherche Pluridisciplinaire Sport Santé Société , F-59000 Lille , France.
authors.forename: Frédéric N
authors.initials: FN
authors.lastname: Daussin
mesh_terms: D000328:Adult; D004734:Energy Metabolism / Q000502:physiology*; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005221:Fatigue / Q000378:metabolism; D000072696:High-Intensity Interval Training; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism*; D010101:Oxygen Consumption; D010807:Physical Endurance / Q000502:physiology*; D005082:Physical Exertion / Q000502:physiology*; D012146:Rest / Q000502:physiology*; D055815:Young Adult
chemical_list: D010100:Oxygen
keywords: VO2; VO2 fluctuations; intermittent exercise; training prescription; work:rest cycle duration