Reliability and circadian rhythmicity of blood lactate

Simple item page
dc.contributor.authorMcFadyen, Paulaen_US
dc.date.accessioned2024-08-14T22:46:56Z
dc.date.available2024-08-14T22:46:56Z
dc.date.copyright1992en_US
dc.date.issued1992
dc.degree.departmentSchool of Physical Education
dc.degree.departmentSchool of Exercise Science, Physical and Health Education
dc.degree.levelMaster of Science M.Sc.en
dc.description.abstractThe reliability in measurement of, the circadian variation in, and the effects of catecholamine concentration on venous and arterialized lactate during rest and exercise were examined in twelve trained males (26.4 ± 5.4 yrs, 76.7 ± 8.5 kg , 180.5 ± 8.5 cm, and 58.1 ± 4.6 ml-kg⁻¹•min⁻¹). The subjects completed four cycle tests each spaced three days apart . Two tests were performed between 0700-0830 h, one at 1200-1330 hand one at 1700-1830 h. To determine blood lactate reliability, an additional 11 male subjects were tested twice between 0700-0830 h. Baseline measures of heart rate (HR), core temperature (T𝒸), ventilation (Vₑ), and oxygen consumption (VO₂) were recorded during minutes 25-30 of rest. Venous blood was drawn from the antecubital vein and was subsequently analyzed for plasma catecholamine and blood lactate concentration. During exercise, power output increased 20-45 W every 3 minutes until ventilatory threshold (VT) and every minute until the criterion endpoint was reached (CEP). Criterion endpoint was determined to be 20-45 W below the power output at which peak VO₂ was reached. All of the cardiorespiratory variables and Tc were measured every minute during exercise and venous and arterialized blood samples were taken at VT and 3 minutes post-CEP. A circadian rhythm was demonstrated in T𝒸, HR, VO₂, and Vₑ at rest with the peak measurement occurring in the evening but only T𝒸 demonstrated a discernable rhythm at VT and CEP. Blood lactate did not demonstrate a circadian rhythm under any of the three measurement conditions. Reliability coefficient for both venous and arterialized lactate were R=0.75 and R=0.81 at VT and were R=0.90 and R=0.90 at CEP respectively. The standard error of measurement (SEM) for venous lactate at the same time of day during exercise ranged between 0.3-0.4 mmol·L-1 and the SEM increased when blood lactate concentration was compared at different times of the day. When blood lactate was sampled from different sites, venous lactate concentration was approximately 1 mmol·L⁻¹ lower than arterialized lactate concentration at VT and CEP. Changes in venous lactate concentration from rest to VT were correlated with changes in morning plasma epinephrine (r=0.81) . The findings of this study suggest that blood lactate measurement is reliable during exercise when sampled during the morning; that differences across sampling sites and concentration of plasma epinephrine affect blood lactate concentration; and during exercise, no discernable circadian changes in cardiorespiratory variables, catecholamines, and blood lactate were apparent at three different sampling times. Eventhough circadian rhythmicity was not a confounding factor in blood lactate concentration during exercise, the low correlations and the large SEM across times suggest that sampling time should be standardized.en
dc.format.extent73 pages
dc.identifier.urihttps://hdl.handle.net/1828/18973
dc.rightsAvailable to the World Wide Weben_US
dc.subjectUN SDG 3: Good Health and Well-Beingen
dc.titleReliability and circadian rhythmicity of blood lactateen_US
dc.typeThesisen_US

Files

Original bundle
Now showing 1 - 1 of 1
Thumbnail Image
Name:
MCFADYEN_Paula_MSC_1992_528670.pdf
Size:
17.88 MB
Format:
Adobe Portable Document Format
Download

Collections

Electronic Theses and Dissertations (ETD)
 
University of Victoria Libraries

We acknowledge and respect the Lək̓ʷəŋən (Songhees and Esquimalt) Peoples on whose territory the university stands, and the Lək̓ʷəŋən and W̱SÁNEĆ Peoples whose historical relationships with the land continue to this day.