The aim of this study was to evaluate time-of-day effects on fatigue during a sustained anaerobic cycling exercise. Sixteen healthy male competitive cyclists were asked to perform a 60 s Wingate test against a braking load of 0.087 kg.kg body mass(-1) during two experimental sessions, which were set up either at 06:00 or 18:00 h in counterbalanced order. There was only one session per day with a recovery period of at least 36 h between the two sessions. Each subject was trained to perform the test. The body mass used to determine the braking load was that of the first test session for each subject and remained constant throughout the two test periods. During the test, peak power (PP), mean power during the first 30 s (MP30 s) and the full 60 s of the test (MP60 s), and fatigue (i.e., the decrease in power output values throughout the exercise) were analyzed. Results confirmed the existence of diurnal variation in anaerobic power output. PP, MP30 s, and MP60 s were significantly higher at 18:00 than 06:00 h, with gains equal to 8.2, 7.8, and 7.8%, respectively. Moreover, all the power output values recorded in the evening were higher than those recorded in the morning, indicating that fatigue induced by this exercise is not affected by time-of-day in male competitive cyclists. It is hypothesized that the freedom and complexity of pedalling could allow adaptations in movement patterns, as a function of time-of-day, in order to maintain higher performance in the evening. For practical considerations, the more complex the movements required to perform a sport, the more the time-of-day effect can be taken into account and adapted to by the trained athlete, particularly in cyclic sporting disciplines such as swimming, running, rowing, and kayaking.

The present study examined to what extent an acute bout of hypotension influences blood flow in the external carotid artery (ECA) and the corresponding implications for blood flow regulation in the internal carotid artery (ICA). Nine healthy male participants were subjected to an abrupt decrease in arterial pressure via the thigh-cuff inflation-deflation technique. Duplex ultrasound was employed to measure beat-to-beat ECA and ICA blood flow. Compared with the baseline normotensive control, acute hypotension resulted in a heterogeneous blood flow response. ICA blood flow initially decreased following cuff release and then returned quickly to baseline levels. In contrast, the reduction in ECA blood flow persisted for 30 s following cuff release. Thus, the contribution of common carotid artery blood flow to the ECA circulation decreased during acute hypotension (-10 ± 4%, P < 0.001). This finding suggests that a preserved reduction in ECA blood flow, as well as dynamic cerebral autoregulation likely prevent a further decrease in intracranial blood flow during acute hypotension. The peripheral vasculature of the ECA may, thus, be considered an important vascular bed for intracranial cerebral blood flow regulation.

The aim of this paper was to validate a French version of the Chronotype Questionnaire (Ogińska, 2011, Pers. Individ. Dif. 50:1039-1043), which represents an interesting novelty in the psychometric assessment of chronotype, because it comprises not only an assessment of the morningness-eveningness (ME) dimension, but also a distinctness (DI) dimension (i.e., amplitude), which represents the range of diurnal variation. In study 1, we aimed to confirm the structure of the Chronotype Questionnaire, with two different samples, young adults (n = 338, mean ± SD = 18.70 ± 1.12 yrs, 244 men and 94 women) and old adults (n = 477, mean ± SD = 55.92 ± 11.9 yrs, 168 men and 310 women). The confirmatory factor analysis (CFA) indicated a poor fit in both samples as well as in the whole sample, which could be due to some inconsistencies in the original instrument, above all in the distinctness dimension. We therefore decided to revise the Chronotype Questionnaire, keeping the ME dimension, but refining the DI dimension. In study 2, with a new sample of 197 participants (mean ± SD = 22.71 ± 2.23 yrs, 105 men and 92 women), we examined the factor structure of the revised scale containing 18 items. The resulting questionnaire contained 16 items (i.e., 8 items on each scale), with item factor loadings higher than .45. In study 3, we aimed to confirm the factor structure of the instrument developed in study 2 as well as to examine its convergent validity, with a new sample of 158 participants (mean ± SD = 55.92 ± 11.9 yrs, 97 men and 61 women). Results of the CFA showed that a good fit of the model could be obtained with 16 items in the questionnaire. The new questionnaire derived from the original Chronotype Questionnaire was from now on called the Caen Chronotype Questionnaire (CCQ). Convergence validity was obtained with the Horne and Östberg questionnaire and the ME scale of the CCQ, showing a negative significant relationship (r = -.82). The CCQ showed promising psychometric qualities, and further research should aim to combine it with physiological variables.