Circadian rhythms in blood lactate concentration during incremental ergometer rowing

Abstract

This study examined whether circadian rhythms affect lactate threshold (Th(lac)) during rowing exercise. Eleven male, endurance-trained athletes [mean (SD) age 29.5 (6.1) years] rowed at 0200, 0600, 1000, 1400, 1800 and 2200 hours under the same experimental conditions. Capillary blood (25 microl) was obtained from the tip of the toe during the last 30 s of a continuous, multi-stage, 3-min, incremental protocol on the Concept II ergometer. To determine Th(lac), a curve-fitting procedure (the D(max) method), a visual method (Th(lac-vis)) and the fixed blood lactate concentration of 4.0 mmol l(-1) (Th(lac-4 mM)) were used. Circadian rhythms were apparent for oxygen consumption and heart rate at Th(lac) using the D(max) method (P=0.02 and P=0.04 respectively), with the acrophases at 2139 hours and 2032 hours respectively coinciding in phase with that of core body temperature. The conclusion is that tests should be completed at the same time of day at which the athlete usually trains, to ensure precision of Th(lac) determination, especially when the D(max )method is used to determine Th(lac).

Circadian Cycle and Its Influence on Parameters of Aerobic Training

“…In the literature we apply the cycle ergometer exercise at various times, such as: 2:00, 6:00, 10:00, 2:00pm, 6:00pm and 10:00pm and has been found that significant circadian variation in the Fc max [10]. Moreover, also the use of cycling were their used the time, 4:00, 8:00, 12:00, 3:00pm, 6:00pm, 9:00pm and 24:00 h [11], and in another study that found no significant differences between the different periods [5], used four times (8:00, 12:00, 4:00pm and 8:00pm) [5].…”

Промена На Крвните Лактати При Ергометриско Тестирање Кај Професионални Фудбалери За Време На Една Натпреварувачка Полусезона

“…Како главна причина за тоа се смета различната ензимска активност. Заради тоа тестовите треба да се направат и во двата дела на денот за да може да се направи разлика од добиените резултати [14].…”

Human circadian rhythms and exercise: Significance and application in real-life situations

“…Interestingly, studies examining other indices of endurance capacity have demonstrated a circadian rhythm or diurnal variation suggesting evening superiority: higher oxygen consumption and heart rate at the lactate threshold intensity 39) , higher aerobic contribution to energy production during 30 seconds of maximal pedaling 40) , and a faster record in a 16.1 km cycling time trial (about 23 minutes) 41) .…”

“…Oxygen consumption and heart rate at the lactate threshold intensity 39) Time to exhaustion in the heat 42) 16.1-km cycling time trial 41) Short-term power output 27,28) No time of day variation Adverse cardiovascular events 45,46,55,56) Exercise-induced adverse cardiovascular events 57,58) Higher risk in the morning than in the afternoon and evening…”