title: Reproducibility of the blood lactate threshold, 4 mmol.l(-1) marker, heart rate and ratings of perceived exertion during incremental treadmill exercise in humans.
abstract: The aim of this study was to investigate the reproducibility of blood lactate measurements, heart rate (HR) and ratings of perceived exertion (RPE) during treadmill exercise at speeds corresponding to the lactate threshold ( v(Th,la)-) and a fixed blood lactate concentration of 4 mmol.l(-1)( v(la)-(,4)). Possible differences in reproducibility related to fitness levels were also investigated. A group of 20 men [mean (SD)] [age 20.5 (1.4) years] and 16 women [age 21.2 (0.9) years] took part in the study. The subjects performed two identical incremental exercise tests consisting of at least six 4 min stages. Blood lactate concentrations, HR and RPE were recorded at the end of each stage. Limits of agreement (LoA), correlation coefficients and 95% confidence intervals for the mean difference between tests were employed to investigate the level of agreement and reproducibility of blood lactate concentration, HR and RPE. For the group as a whole, the sample correlation coefficient for speed at v(Th,la)- was r=0.88, and was r=0.92 for the speed at v(la)-(,4). At v(Th,la) -, the correlation coefficients for the moderately fit and unfit were r=0.94 and r=0.36, respectively, and at v(la)-(,4) r=0.93 and r=0.68, respectively. The LoA for the moderately fit group indicated that a change of 1.62 km.h(-1) in v(Th,la)- would be necessary to be considered a change in training status. For HR and RPE, relationships between the tests were generally poor. The LoA suggested that changes in scores must be unacceptably large. These findings cast doubt on the sensitivity of testing for change of blood lactate concentration, HR and RPE in this population.
authors.affiliation: Institute of Biomedical and Life Sciences, University of Glasgow, 64 Oakfield Avenue, G12 8LT, UK. S. Grant@biomed.gla.ac.uk
authors.forename: S
authors.initials: S
authors.lastname: Grant
authors.forename: K
authors.initials: K
authors.lastname: McMillan
authors.forename: J
authors.initials: J
authors.lastname: Newell
authors.forename: L
authors.initials: L
authors.lastname: Wood
authors.forename: S
authors.initials: S
authors.lastname: Keatley
authors.forename: D
authors.initials: D
authors.lastname: Simpson
authors.forename: K
authors.initials: K
authors.lastname: Leslie
authors.forename: S
authors.initials: S
authors.lastname: Fairlie-Clark
mesh_terms: D000328:Adult; D015444:Exercise / Q000502:physiology / Q000523:psychology; D005080:Exercise Test; D005260:Female; D006321:Heart / Q000502:physiology*; D006339:Heart Rate; D006801:Humans; D019344:Lactic Acid / Q000097:blood*; D008297:Male; D010465:Perception / Q000502:physiology*; D005082:Physical Exertion / Q000502:physiology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013223:Statistics as Topic
chemical_list: D019344:Lactic Acid