title: Sex and Exercise Intensity Do Not Influence Oxygen Uptake Kinetics in Submaximal Swimming.
abstract: The aim of this study was to compare the oxygen uptake ([Formula: see text]) kinetics in front crawl between male and female swimmers at moderate and heavy intensity. We hypothesized that the time constant for the primary phase [Formula: see text] kinetics was faster in men than in women, for both intensities. Nineteen well trained swimmers (8 females mean ± SD; age 17.9 ± 3.5 years; mass 55.2 ± 3.6 kg; height 1.66 ± 0.05 m and 11 male 21.9 ± 2.8 years; 78.2 ± 11.1 kg; 1.81 ± 0.08 m) performed a discontinuous maximal incremental test and two 600-m square wave transitions for both moderate and heavy intensities to determine the [Formula: see text] kinetics parameters using mono- and bi-exponential models, respectively. All the tests involved breath-by-breath analysis of front crawl swimming using a swimming snorkel. The maximal oxygen uptake [Formula: see text] was higher in men than in women [4,492 ± 585 ml·min-1and 57.7 ± 4.4 ml·kg-1·min-1vs. 2,752.4 ± 187.9 ml·min-1(p≤ 0.001) and 50.0 ± 5.7 ml·kg-1·min-1(p= 0.007), respectively]. Similarly, the absolute amplitude of the primary component was higher in men for both intensities (moderate: 1,736 ± 164 vs. 1,121 ± 149 ml·min-1; heavy: 2,948 ± 227 vs. 1,927 ± 243 ml·min-1,p≤ 0.001, for males and females, respectively). However, the time constant of the primary component (τp) was not influenced by sex (p= 0.527) or swimming intensity (p= 0.804) (moderate: 15.1 ± 5.6 vs. 14.4 ± 5.1 s; heavy: 13.5 ± 3.3 vs. 16.0 ± 4.5 s, for females and males, respectively). The slow component in the heavy domain was not significantly different between female and male swimmers (3.2 ± 2.4 vs. 3.8 ± 1.0 ml·kg-1·min-1,p= 0.476). Overall, only the absolute amplitude of the primary component was higher in men, while the other [Formula: see text] kinetics parameters were similar between female and male swimmers at both moderate and heavy intensities. The mechanisms underlying these similarities remain unclear.
authors.affiliation: Laboratory of Physiology and Biochemistry of Exercise, Faculty of Human Kinetics, University of LisbonLisbon, Portugal; Ciper, Faculty of Human Kinetics, University of LisbonLisbon, Portugal; Universidade EuropeiaLisbon, Portugal.
authors.forename: Joana F
authors.initials: JF
authors.lastname: Reis
authors.affiliation: Department of Physiology, Faculty of Biology and Medicine, Institute of Sport Sciences, University of Lausanne Lausanne, Switzerland.
authors.forename: Gregoire P
authors.initials: GP
authors.lastname: Millet
authors.affiliation: Ciper, Faculty of Human Kinetics, University of Lisbon Lisbon, Portugal.
authors.forename: Paula M
authors.initials: PM
authors.lastname: Bruno
authors.affiliation: Ciper, Faculty of Human Kinetics, University of Lisbon Lisbon, Portugal.
authors.forename: Veronica
authors.initials: V
authors.lastname: Vleck
authors.affiliation: Laboratory of Physiology and Biochemistry of Exercise, Faculty of Human Kinetics, University of LisbonLisbon, Portugal; Ciper, Faculty of Human Kinetics, University of LisbonLisbon, Portugal.
authors.forename: Francisco B
authors.initials: FB
authors.lastname: Alves
keywords: female swimmers; oxygen consumption; slow component; time constant; trained swimmers