Morning-evening Differences Research Articles

Morning-evening differences of short-term maximal performance and psychological variables in female athletes.

The aim of this study was to examine the effect of time of day on short-term maximal performance and psychological variables in young females. Fifteen active women participated in the study (age: 22 ± 3years) and completed Hooper and the POMS-F questionnaires subsequently. In a randomized order, they performed a maximum of 30s cycling exercise at two different times of day: in the morning at 07:00h and in the afternoon at 16:00h with a recovery period of 48h. The digit cancellation test, countermovement jump (CMJ), squat jump (SJ) test, and the lower quarter Y balance test were performed at the beginning and at the end of each session. Our results showed that only peak power and mean power (p < 0.01) during the maximum 30s cycling, reaching distances during the Y-balance (p < 0.05), Jump height in CMJ and SJ (p < 0.01) as well as attention, vigor, and stress scores (all p < 0.01) were higher in the afternoon than in the morning. Our results indicated a daily diurnal variation in short-term maximal performance and mood states in young athletic women with better performance observed during the afternoon.

Diurnal and seasonal differences in cardiopulmonary response to exercise in morning and evening chronotypes

ABSTRACT Circadian clocks regulate multiple physiological domains from molecular to behavioral levels and adjust bodily physiology to seasonal changes in day length. Circadian regulation of cellular bioenergy and immunity in the cardiovascular and muscle systems may underpin the individual diurnal differences in performance capacity during exercise. Several studies have shown diurnal differences in cardiopulmonary parameters at maximal and submaximal workloads in morning and evening circadian human phenotypes. However, the effect of seasons on these changes was not elucidated. In this study, we recruited subjects with Morningness–Eveningness Questionnaire scores corresponding to morning and evening types. Subjects underwent morning (7:00–9:00) and evening (20:00–22:00) maximal workload spiroergometry in both winter and summer seasons. We analyzed their performance time, anaerobic threshold, heart rate, and respiratory parameters. Our results suggest that evening types manifest diurnal variations in physical performance, particularly in winter. They also have slower heart rate recovery than morning types, irrespective of the time of day or season. Compared to winter, the chronotype effect on the magnitude of morning–evening differences in performance time, maximal heart rate, and anaerobic threshold onset was more significant in summer. Our data are in concordance with previous observations and confirm the difference between morning and evening types in the timing of maximum performance capacity.

Variability of Lipids in Human Milk

Lipids in breastmilk play a critical role in infant growth and development. However, few studies have investigated sources of variability of both high- and low-abundant milk lipids. The objective of our study was to investigate individual and morning–evening differences in the human milk lipidome. In this study, a modified two-phase method (MTBE: Methanol 7:2) was validated for the extraction of lipids from human breastmilk. This method was then applied to samples from a group of 20 healthy women to measure inter- and intra-individual (morning versus evening) variability of the breastmilk lipidome. We report here the levels of 237 lipid species from 13 sub-classes using reversed-phase liquid chromatography mass spectrometry (RP-LCMS) and direct-infusion mass spectrometry (DI-MS). About 85% of lipid species showed stable inter-individual differences across time points. Half of lipid species showed higher concentrations in the evening compared with the morning, with phosphatidylethanolamines (PEs) and triacylglycerols (TAGs) exhibiting the largest changes. In morning and evening samples, the biological variation was greater for diacylglycerols (DAGs) and TAGs compared with phospholipids and sphingolipids, and the variation in DAGs and TAGs was greater in evening samples compared with morning samples. These results demonstrate that variation in the milk lipidome is strongly influenced by individual differences and time of day.

Effect of Difficulty Level and Time-Pressure on the Morning-Evening Differences in Accuracy and Consistency of Throwing Darts Among 9-10 Year-Old Boys

This study investigated the impact of task difficulty level and time-pressure on the morning-evening changes in psychomotor performance and perceived difficulty to it among 9–10 years-old boys. Twelve healthy right-handed boys (age = 9.8 ± 0.5 years, height = 144 ± 6.2 cm and body mass = 32.7 ± 3.4 kg) volunteered to take part in the study. They were asked to throw darts to a target from a short (2m, SD) and long (2.37m, LD) distances, either in free (no time limitation, NC) or time-pressure (TPC) conditions, on nonconsecutive days and in a counter-balanced randomized order. Mean scores, missed darts and variability of scores were recorded and analyzed using a three-way ANOVA with repeated measures. Intra-aural temperature and perceived difficulty were recorded too. The results showed higher performance in the afternoon than the in the morning, with higher mean scores around the time of maximum oral temperature (p<0.001). The number of missed darts and variability of scores were lower at 17:00 h in comparison with 07:00 h (p<0.05). Perceived difficulty decreased significantly with time-of-day, with greater values at 07:00 h than at 17:00 h (p<0.05). Psychomotor performance was better in the afternoon than the morning. It seems that, in the early morning, children are less sensitive to the increased level of difficulty when under time-pressure than when throwing a greater distance from the target.

The effect of time of day on short-term maximal performance in obese and non-obese young men

The purpose of this study was to examine time-of-day effects on short-term performance in obese young men. In a balanced study design, 30 boys were divided into two groups: obese (OG; n = 15) and non-obese (CG; n = 15) groups. Both groups performed anaerobic tests of strength and power (squat-Jump, SJ; counter-movement jump, CMJ; 10-m sprint; and 30-m sprint) at 08:00 and 17:00 h on separate days. The results showed morning–evening differences in all variables in CG, with significant increases at 17:00 h (around the time of peak temperature) in comparison with 08:00 h (p < 0.01) for OG. However, such morning-evening differences were not found in the OG, except for the 30-m sprint. Obesity affects the diurnal variation on performances of 30-m sprint with a significant decrease in the evening for OG of 1.23% (p < 0.01). A correlation between anaerobic performance and oral temperature was observed only in the 30-m sprint test. In conclusion, the findings of the present study indicated that obesity is a problem that can affect circadian rhythms and performance in obese young men; therefore, preventing childhood obesity should become a top priority in efforts to improve performance and health.

Diurnal variation in stroke parameters and motor organization in front-crawl swimmers

The aim of the present study was to examine the effects of time of day on stroke parameters and motor organization in front-crawl swimmers. In a randomized order, fourteen regional swimmers (age: 18.7 ± 1.6 years) performed maximal front crawls over 12.5 m during two experimental sessions; the morning sessions were conducted between 07:00 and 09:00 h and the evening experiments were conducted between 17:00 and 19:00 h. Stroke parameters (swim velocity, stroke rate [SR], and stroke length), motor organization (arm stroke phases and arm coordination) were calculated from aerial and underwater side-view cameras. Arm coordination was quantified in terms of an index of coordination (Idc). Results showed that oral temperature was significantly higher in the evening 36.8 ± 0.2 °C than in the morning 36.1 ± 0.2 °C (p < 0.001), with a morning–evening difference of −0.7 ± 0.1 °C. Performance was also higher in the evening (7.4 ± 0.6 s) than in the morning (8.0 ± 0.8 s) (p < 0.001), with a morning–evening difference of 0.55 ± 0.30 s. Likewise, values of swim velocity and SR were higher in the evening than in the morning (p < 0.001) with morning–evening differences of −0.10 ± 0.04 m s−1 and −3.99 ± 2.91 cycles min−1, respectively. Percentage Idc increased significantly (p < 0.01) between the morning (−5.1 ± 6.5%) and evening (−1.6 ± 7.0%). It is concluded that maximal swimming trials are performed better in the evening than the morning, and that this might be explained by better stroke parameters and motor organization at this time.

Effect of sport practice and warm-up duration on the morning–evening difference in anaerobic exercise performance and perceptual responses to it

This study was designed to assess the effect of sport practice and warm-up duration on the morning–evening differences in muscle power and fatigue during performance of anaerobic exercise and perceptual responses to it. Twenty-two male physical education students – twelve trained (TG) (21.51 ± 1.25 years, 182.17 ± 4.37 cm and 82.88 ± 11.23 kg) and ten untrained (NTG) (23.89 ± 3.17 years, 176.8 ± 2.2 cm and 82.24 ± 8.43 kg) – participated in a crossover randomized study. They were asked to perform a 30-s Wingate test during six experimental sessions (three at 08:00 and three at 18:00 h) after different active warm-up (AWU) durations (5 min, 15 min, or 20 min). The AWU consisted of pedaling at a constant pace of 60 rpm against 50% of maximal aerobic power. Rate of perceived exertion (RPE) was recorded after the AWU and again immediately after the Wingate test. Heart rate and temperature (T) were recorded during each session at rest, after AWU and immediately at the end of the Wingate test. During the Wingate test, peak power (PP), mean power (MP), and the fatigue index were recorded. While the RPE estimations were higher in NTG, no time-of-day effect was recorded in either experimental group (morning or evening). T, PP, and MP were higher in the afternoon than in the morning (p < 0.001 for PP and MP; p < 0.05 for T). Similarly, PP and MP during the Wingate test were significantly higher in the TG than in the NTG (p < 0.001). The morning–evening difference of PP and MP was affected by AWU duration; AWU15 was best in the morning for improving lower limb power for both the TG and NTG, whereas reducing this period to 5 min in the evening was appropriate for TG only.

Morning–evening differences in response to exhaustive severe-intensity exercise

The aim was to investigate the effect of time of day on 4 variables that are related to sport performance. Twenty healthy young men (mean ± SD: 22 ± 3 years, 1.78 ± 0.08 m, 72.0 ± 7.0 kg) performed exhaustive severe-intensity cycle ergometer tests at 278 ± 35 W (3.8 ± 0.4 W·kg(-1)) in the morning (between 0630 h and 0930 h) and in the evening (between 1700 h and 2000 h). Despite that gross efficiency was lower in the evening (estimated oxygen demand was 6% higher, P < 0.05), time to exhaustion was 20% greater (P < 0.01) in the evening (329 ± 35 s) than in the morning (275 ± 29 s). Performance in the evening was associated with a 4% higher (P < 0.01) maximal oxygen uptake (54 ± 7 mL·kg(-1)·min(-1) vs. 52 ± 6 mL·kg(-1)·min(-1), for the evening and the morning, respectively) and a 7% higher (P < 0.01) anaerobic capacity (as reflected by maximal accumulated oxygen deficit: 75 ± 9 mL·kg(-1) vs. 70 ± 7 mL·kg(-1), for the evening and the morning, respectively). In addition, oxygen uptake kinetics was faster in the evening, which resulted in slower utilization of the anaerobic reserves. It is concluded that modest morning-evening differences in maximal oxygen uptake, anaerobic capacity, and oxygen uptake kinetics conflate to produce a markedly longer performance in the evening than in the morning. Time of day must be considered for exercise testing and perhaps for exercise training.

Chronobiological Characteristics of Neuropathic Pain

Neuropathic pain is often worse at night; however, little is known about pain rhythmicity during waking hours. We aimed to replicate previous observations of diurnal pain progression, evaluate associations between diurnal rhythmicity and clinical factors, and evaluate the impact of diurnal rhythmicity on treatment response. We performed exploratory analyses of 2 trials (The New England Journal of Medicine 2005; 352:1324; The Lancet 2009; 374:1252) in diabetic neuropathy and postherpetic neuralgia. Pain recorded at 8:00 AM, 4:00 PM, and 8:00 PM, at baseline and during drug treatment was examined. Data from the latest trial replicated our previous observation of diurnal pain progression with a relative pain intensity difference of 33% between 8:00 AM and 8:00 PM. This pattern was preserved during treatment with gabapentin, nortriptyline, and their combination. Pooled multivariable analyses suggested that difference in pain intensity from 8:00 AM to 8:00 PM was more pronounced in females (vs. males) and in diabetic peripheral neuropathy (vs. postherpetic neuralgia). The baseline magnitude of pain intensity difference from 8:00 AM to 8:00 PM failed to predict treatment response. These observations suggest that neuropathic pain progressively increases throughout the day with clinically relevant morning-evening differences and further indicate that sex and underlying etiology may be important determinants of diurnal rhythmicity in neuropathic pain. Consideration of these patterns may guide improved therapeutic strategies and stimulate new directions of research that will improve our understanding and treatment of neuropathic pain.

Seasonal Variations of Daily Changes in Blood Pressure Among Hypertensive Patients with End-Stage Renal Diseases

Hypertension is a well-known cardiovascular risk. Patients with end-stage renal diseases frequently suffer hypertension, and their blood pressure elevates in winter. However, seasonal changes in daily variations of blood pressure are poorly assessed in patients treated with hemodialysis. Thirty hypertensive patients with end-stage renal diseases were enrolled in the study. Dry weight and antihypertensive medications were altered when they were necessary. Home blood pressure measurements were performed at least for 1 week in each season; April–May 2008, July–August 2008, October–November 2008, and January–February 2009. Both morning and evening systolic blood pressures (SBPs) showed significant seasonal changes ( p < 0.01), with the highest blood pressure in winter (162 ± 18 and 135 ± 22 mmHg in morning and evening). Morning diastolic blood pressure (DBP) also exhibited seasonal changes ( p < 0.05), with the highest blood pressure in fall ( 78 ± 8 mmHg). Evening DBP did not manifest seasonal deviations. Morning-evening differences in SBP and DBP were the greatest in winter (28 ± 21 and 10 ± 9 mmHg in SBP and DBP, p < 0.01), and the smallest in summer (16 ± 12 and 6 ± 5 mmHg). Daily variations of SBP and DBPs in spring (19 ± 12 and 7 ± 6 mmHg) and fall (20 ± 13 and 9 ± 8 mmHg) were between those of summer and winter. Our results indicate that not only averaged blood pressure but also variations of blood pressure in winter are larger than the other seasons, and suggest that these blood pressure variations participate in cardiovascular events in hypertensive patients with end-stage renal diseases.

Low Doses of Dexamethasone Affect Immune Parameters in the Absence of Immunological Stimulation

Recent findings suggest an important role of subtle changes in the plasma levels of inflammatory cytokines within the brain-immune interplay. It is unclear how such changes are regulated in the absence of acute inflammatory or infectious stimuli. Endocrine systems are a good candidate, because innate immunity and the hypothalamo-pituitary-adrenal (HPA)-system are closely related: glucocorticoids have immunosuppressive properties and modulate cytokine release from stimulated mononuclear blood cells in vitro and the immune response in vivo, but it still remains unclear, whether they also modulate circulating cytokine levels in the absence of immunological stimuli. We measured the influence of 1.5 or 3.0 mg dexamethasone (DEX) per os at 09:00 or 21:00 hours on body temperature, cortisol plasma levels, differential white blood cell counts, and cytokine plasma levels in 40 healthy male volunteers using a double-blind, placebo-controlled study design. In addition to significant morning-evening differences in tympanic temperature and several immune parameters, we found that DEX-intake significantly increased tympanic temperature, decreased cortisol plasma levels, altered differential white blood cell counts and induced changes in unstimulated plasma cytokine levels. Whereas the levels of TNF-alpha and sTNF-R p75 were reduced, the levels of sTNF-R p55 increased after a transient decrease.

Daily changes in β-adrenergic sensitivity of rat submandibular gland. Correlation with β-adrenoceptor rhythm.

Neurons from the superior cervical ganglia (SCG) innervate the submandibular gland and release noradrenaline during the dark phase of the daily photoperiod. Since in the pineal, another structure innervated by sympathetic neurons, nocturnal activation of the SCG is associated with β-adrenergic sub- and super-sensitivity rhythms, the possible existence of similar phenomena in the rat submandibular gland was assessed. Wistar female rats, kept on a 14:10 light/dark cycle (light from 06:00 to 20:00 h), were sacrificed at 09:00, 14:00, 20:00, 24:00 and 04:00 h. β-Adrenoceptors were studied by 3H-dihydroalprenolol binding to membrane preparations. The equilibrium dissociation constant ( K d) did not change as a function of time while significant daily variations in maximal binding values ( B max) were observed with a peak at 20:00 h. Changes in B max correlated with a high response of adenylate cyclase to isoproterenol. In addition, when the response in salivary flow to isoproterenol was measured, a shift to the left (about 1 logarithmic unit) in dose–response curves was observed at 19:00–20:00 h as compared to 08:00–09:00 h. These daily variations in isoproterenol responsiveness seem not to depend on the pattern of eating since a 24-h starvation or a nocturnal starvation for 16–18 days did not abolish the morning–evening differences in the salivary flow response to isoproterenol. Rather, the results suggest that the daily variations in isoproterenol response correlate with β-adrenergic super- and sub-sensitivity phenomena associated with the circadian release of noradrenaline from SCG neurons.

The Pituitary-Adrenocortical System of Neonatal Rats Is Responsive to Stress throughout Development in a Time-Dependent and Stressor-Specific Fashion*

The responsiveness of the neonatal hypothalamus-pituitary-adrenal (HPA) axis to stress has been thought to be impaired or diminished during the first 2 weeks of life. Although we previously found full responsiveness of the hypothalamus-pituitary unit to adrenalectomy in young rats [days (d) 5-10], we failed to measure a significant increase in ACTH 10 min after ether administration until d14 of age. These studies were, therefore, designed to test the functional activation of the HPA axis after a single or repeated exposures to stress. Both qualitative (time-course, stressor-specific, circadian) and quantitative changes in the ACTH and corticosterone (B) responses to various stressors were tested during the first 10 days of life. Exposure to 3 min of ether vapor increased ACTH and B secretion (P less than 0.05-0.01) in 1-, 5-, and 10-d-old rats, with an increasing amplitude of both ACTH and B responses as a function of age. Peak secretion of ACTH occurred 5 min after the onset of stress (122 +/- 3.8 to 359 +/- 54 pg/ml on d1-10), while the time of maximal B increased as a function of age. Other stressors, such as maternal separation (12 h), cold (4 C; 60 min), or histamine injection (4 mg/kg BW, ip), provoked significant and stressor-specific ACTH and B responses in 10-d old rats. Histamine administration increased ACTH secretion above that of vehicle-injected rats, with a peak of secretion 15 min after drug injection (272 +/- 29 vs. 127 +/- 8 pg/ml; P less than 0.01). Histamine-induced B secretion peaked at 60 min (3.7 +/- 0.5 micrograms/dl). In contrast to early responses observed after ether, separation, or histamine stress, cold stress in 10-d-old pups caused a large ACTH and B release 4 h after the onset of cold compared to that in maternally deprived pups [ACTH: cold, 457 +/- 61 pg/ml; separated, 150 +/- 14 (P less than 0.01); B: cold, 3.3 +/- 0.4 micrograms/dl; separated, 1.8 +/- 0.2 (P less than 0.05)]. We did not detect morning-evening (AM-PM) differences in either the pattern or the magnitude of the ACTH or B response to maternal separation or cold stress. Suppression of cold-induced ACTH release by B injection (1 mg/kg BW) 2 h before stress was observed until 4 h after stress in the AM and PM, whereas when given after cold, B was less effective in the PM than in the AM at preventing the rise in ACTH levels observed at 4 h.(ABSTRACT TRUNCATED AT 400 WORDS)

Circadian rhythm and neural regulation of rat pineal angiotensin converting enzyme

Angiotensin converting enzyme was detectable in rat pineal gland and exhibited a circadian rhythm in activity with maximum at the end of the light phase of daily photoperiod. Superior cervical ganglionectomy (SCGx) or exposure to light for 6 days increased enzyme activity and obliterated morning-evening differences, whereas injection of the β-agonist isoproterenol depressed the high values observed in SCGx animals. These results indicate that angiotensin converting enzyme in the pineal gland is under negative control by the norepinephrine released from pineal sympathetic nerves.

Return of pituitary-adrenal function after adrenal enucleation or transplantation: diurnal rhythms and responses to ether.

Adrenocortical diurnal rhythms and responses to ether vapor were studied in rats 1, 3, and 5 weeks after bilateral adrenal enucleation, autotransplantation, or sham transplantation in order to 1) determine whether diurnal rhythms in the plasma corticosterone concentration and adrenal responsiveness to ACTH are dependent on innervation of the adrenals, 2) compare regeneration of function of transplanted and enucleated adrenals, and 3) investigate adrenal mass-related nonsteroidal inhibition of ether-stimulated ACTH secretion. Rats in both enucleate and transplant groups exhibited significant morning-evening differences in adrenal and plasma corticosterone concentrations and significant adrenocortical responses to ether 3 and 5 weeks, but not 1 week, after surgery. The morning-evening differences in corticosterone concentration occurred in the absence of significant morning-evening variation in the plasma ACTH concentration, supporting our previous finding of a diurnal rhythm in adrenal responsiveness to ACTH. The responsiveness rhythm cannot be dependent on adrenal nerves unless transplanted adrenals receive functionally specific reinnervation within 3 weeks. The processes of regeneration of function after enucleation and after transplantation are similar; there were no differences in plasma or adrenal corticosterone values between rats in enucleate and transplant groups at any time or under any condition tested. As regeneration progressed, plasma ACTH responses to ether declined in both enucleate and transplant groups in the absence of changes in plasma corticosterone feedback. These results support our previous finding of adrenal mass-related nonsteroidal suppression of ACTH responses to ether.

Progesterone and 5 alpha-pregnane-3,20-dione in serum of peripartum rhesus monkeys.

To determine whether there are qualitative or quantitative changes in placental steroidogenesis related to the time of day and onset of parturition in the rhesus monkey, systemic venous levels of progesterone (P) and 5α-pregnane- 3,20-dione (DHP) were measured by RIA at 0900 and 2100 h pre- and postpartum. To establish that these steroids were in fact secreted from the uterus and/or its contents, their concentrations were also determined at various stages of pregnancy in peripheral and uterine venous sera obtained during laparotomy. Throughout gestation, P and DHP were secreted from the uterus and/or its contents, as indicated by higher steroid levels in uterine than femoral veins. In prepartum monkeys, peripheral P and DHP concentrations were higher at 2100 than at 0900 h (P < 0.001), and in those animals sampled twice daily up to and including the day of parturition, P and DHP levels at 0900 h averaged 2.4 and 0.26 ng/ml, respectively, while at 2100 h, P and DHP were 5.9 and 0.61 ng/ml, respectively. No major variations in steroid levels were noted before parturition during the morning or evening. In two postpartum lactating monkeys in which peripheral steroids were measured twice daily, no significant morning-evening differences were noted. Since corpora lutea in these animals reportedly continue to secrete progestins, the nocturnal increase in steroid levels found prepartum may reflect an alteration in placental steroid secretion. However, the possible cause or significance of this increase and its relationship to parturition remain to be established.