Breathing techniques are part of traditional relaxation methods; however, their influence on psychophysiological variables related to sleep is still unclear. Consequently, the aim of this paper was to investigate the influence of a 30-day slow-paced breathing intervention compared to social media use on subjective sleep quality and cardiac vagal activity (CVA, operationalized via high-frequency heart rate variability). Healthy participants (n = 64, 33 male, 31 female, M = 22.11, SD = 3.12) were randomly allocated to an experimental or control group. In the experimental group, they had to perform slow-paced breathing for 15 min each evening across a 30-day period. This was administered through a smartphone application. The control group used social media (e.g., Facebook, Instagram, Whatsapp) for the same duration. The night before and after the intervention, their CVA was assessed via a light portable Electrocardiogram (ECG) device, and they had to fill out the Pittsburgh Sleep Quality Index questionnaire. Results showed that in comparison to the use of social media, the slow-paced breathing technique improved subjective sleep quality and increased overnight CVA, while a tendency was observed for morning awakening CVA. Slow-paced breathing appears a promising cost-effective technique to improve subjective sleep quality and cardiovascular function during sleep in young healthy individuals.

The aim of the present study was to examine the effects of a combination of gradual and rapid body mass loss on the physical performance and psychological state of elite judo athletes. Participants were divided into two groups: the experimental (diet) group needed to reduce body mass by 2–6%, whereas the control group did not need to lose body mass. Body mass, percentage of body fat, vertical jump, repetitions of judo movements, rowing with additional loads, and the Profile of Mood States were assessed at 4 weeks before a championship and again one day before the same championship. Compared with 4 weeks before the championship, the experimental group showed a significant decrease in body mass (−4 ± 1.1%, P < 0.05), estimated body fat (−10 ± 4.0%, P < 0.05), and judo movement repetitions over 30 s (−4.5 ± 2.7, P < 0.05), and an increase in scores for confusion (−14.6 ± 7.9, P < 0.05) and tension (−10.1 ± 12.5, P < 0.05), but a decrease in vigour (11.3 ± 8.5, P < 0.05), one day before the championship. There was no difference in squat jump or countermovement jump performance or in judo movement repetitions over 5 s. Our results show that for the experimental group some aspects of performance were impaired one day before a competition, but performance of judo movements over 5 s was not affected.

The aim of this study was to follow the circadian fluctuation of the spontaneous pedal rate and the motor spontaneous tempo (MST) in a sample of highly trained cyclists. Ten subjects performed five...

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.