title: Identification of critical intensity from a single lactate measure during a 3-min, submaximal cycle-ergometer test.
abstract: We tested the hypothesis that critical intensity in cycling can be determined from a single delta blood lactate in the third minute of a submaximal cycle ergometer trial. Fourteen healthy young men performed four to six constant-power-output trials on a cycle ergometer to the limit of tolerance. Critical intensity was calculated via a linear model and subsequently validated. Lactate was measured at baseline and at 3 min from exercise onset. Delta lactate was the difference between these measures. Based on individual trials, we obtained the delta lactate-% validated critical intensity relationship and thereafter an estimate of critical intensity was computed. Validated and estimated critical intensity were compared by effects sizes, paired-sample t-test and Bland-Altman analysis. Delta lactate was a linear function of the intensity of exercise, expressed as % validated critical intensity (R2= 0.89). Estimated critical intensity was not different from (d = 0.03, P = 0.98) and highly correlated with (R2= 0.88) validated critical intensity. The bias between measures was 0.03 W (≠0) with a precision of 7 W. The results suggest that critical intensity in cycling can be accurately and precisely determined from delta lactate during a sub-maximal trial and so provides a practical and valid alternative to direct determination.
authors.affiliation: a Department of Neurosciences, Biomedicine and Movement Sciences , University of Verona , Verona , Italy.
authors.forename: Federico Y
authors.identifier: http://orcid.org/0000-0002-0679-6869
authors.initials: FY
authors.lastname: Fontana
authors.affiliation: a Department of Neurosciences, Biomedicine and Movement Sciences , University of Verona , Verona , Italy.
authors.forename: Alessandro L
authors.identifier: http://orcid.org/0000-0001-9091-2473
authors.initials: AL
authors.lastname: Colosio
authors.affiliation: b Canadian Centre for Activity and Aging The University of Western Ontario , London , Canada.|c School of Kinesiology , The University of Western Ontario , London , Canada.
authors.forename: Daniel A
authors.identifier: http://orcid.org/0000-0002-5656-373X
authors.initials: DA
authors.lastname: Keir
authors.affiliation: d Faculty of Kinesiology , University of Calgary , Calgary , Canada.
authors.forename: Juan M
authors.identifier: http://orcid.org/0000-0002-6460-6453
authors.initials: JM
authors.lastname: Murias
authors.affiliation: a Department of Neurosciences, Biomedicine and Movement Sciences , University of Verona , Verona , Italy.
authors.forename: Silvia
authors.identifier: http://orcid.org/0000-0002-4394-8550
authors.initials: S
authors.lastname: Pogliaghi
mesh_terms: D000328:Adult; D015308:Anaerobic Threshold; D001642:Bicycling / Q000502:physiology*; D016552:Ergometry; D005080:Exercise Test; D006801:Humans; D019344:Lactic Acid / Q000097:blood*; D016014:Linear Models; D008297:Male; D055815:Young Adult
chemical_list: D019344:Lactic Acid
keywords: Critical intensity; critical power; exercise tolerance; functional evaluation; lactate