The effect of strength training at the same time of the day on the diurnal fluctuations of muscular anaerobic performances

The aim of this study was to examine the effects of training at the same time of the day on the diurnal variations of anaerobic performances to provide some recommendations to adjust training hours with the time of the day of competitive events. Thirty participants underwent 8 weeks of lower-extremity progressive resistance training performed 3 times per week designed to promote muscular strength and power. These subjects were randomly assigned to a morning training group (MTG, 07:00-08:00 hours, n = 10), an evening training group (ETG, 17:00-18:00 hours, n = 10), and a control group (CG, completed all tests but did not train, n = 10). Performance in the squat jump, the countermovement jump, the Wingate and 1 repetition maximum (1RM) during leg extension, leg curl, and squat tests was recorded just before and 2 weeks after an 8-week course of regular training. For all the subjects, the morning and evening tests were scheduled at the same time of the day as for the morning and evening training sessions. Before training, the results indicated a significant increase in performance from morning to evening tests (ca. 2.84-17.55% for all tests) for all groups. After training, the diurnal variations in anaerobic performances were blunted in the MTG. In fact, there was no significant difference in muscular power or strength between morning and evening tests. However, these intradaily variations in anaerobic performances persisted in the ETG and CG. From a practical point of view, adaptation to strength training is greater at the time of the day at which training was scheduled than at other times.     

The effect of training at the same time of day and tapering period on the diurnal variation of short exercise performances

The purpose of this investigation was to assess the effects of training and tapering at the same time of the day on the diurnal variations of short exercise performances. Thirty-one physically active men underwent 12 weeks of lower-extremity resistance training and 2 weeks of tapering. These subjects were matched and randomly assigned to a morning training group (MTG, training times 0700-0800 hours, n = 10), an evening training group (ETG, training times 1700-1800 hours, n = 11), and a control group (CG, completed all tests but did not train, n = 10). Muscular strength and power testing was conducted before (T0) and after 12 weeks of training (T1) and after 2 weeks of tapering (T2) in the morning (0700-0800 hours) and in the evening (1700-1800 hours). All morning and evening tests were performed in separate sessions (minimum interval = 36 hours) in a randomized design. In T0, the oral temperature and performances during the Wingate, vertical jump (squat jump and countermovement jump), and maximal voluntary contraction tests were higher in the evening than in the morning for all the groups. In T1, these diurnal variations were blunted in the MTG and persisted in the ETG and CG. In T2, the 2 weeks of tapering resulted in further time of day-specific adaptations and increases in short-term maximal performances. However, there was no significant difference in the relative increase between the MTG and the ETG after both training and tapering. From a practical point of view, if the time of competition is known, training and tapering sessions before a major competition must be conducted at the same time of the day at which one's critical performance is programmed. Moreover, if the time of the competition is not known, a tapering phase after resistance training program could be performed at any time of the day with the same benefit.     

Collegiate rowing crew performance varies by morningness-eveningness

During adolescence and early adulthood, most humans are predisposed developmentally, both biologically and socially, toward evening/night activity. The morningness-eveningness (M-E) tendency to be an evening-preferring (E-type) rather than a morning-preferring (M-type) or intermediate/neither (N-type) "chronotype" may affect athletic performance at various times of day. This study evaluated M-E effects on rowing performance of an intact, experienced, university club crew with near-daily early morning (0500-0700 hours) and late afternoon (1630-1800 hours) training schedules. The hypothesis tested was that chronotype would modify circadian effects during morning and afternoon performances. Eight men and eight women (mean age 19.6 +/- 1.5 years) were tested in a randomized, counterbalanced design. A standard qualifying 2000-m ergometer rowing sprint and a nonroutine standing broad jump task were measured during early morning and late afternoon, separated by 3 days of rest. Each subject's chronotype was determined using two standard self-rating M-E scales, resulting in eight E-type (three women/five men), four M-type (two women/two men), and four N-type (three women/one man) subjects. The rowing results show that E-type and N-type subjects did not differ between morning and afternoon rowing performances, whereas M-type subjects rowed significantly faster in the morning. In contrast, the standing broad jump showed no consistent time-of-day or chronotype effect. These findings suggest that basic performance timing in young athletes is determined to some extent by naturally occurring M-E predispositions. Further, modification of time-of-day influences may be possible by routine practice at the same time each day, as was suggested here by the absence of evening superiority in performances. Understanding their personal M-E tendencies could allow young athletes to arrange training schedules at specific times of day to help counteract any natural circadian influences that might work against their performance.     

The effect of training at the same time-of-day on the diurnal variations of technical ability and swimming performance

The aim of this study was to examine the effects of training at the same time of day on diurnal variations of technical ability and swimming performance, to provide some recommendations with regard to adjusting training hours in accord with the time of day of competitive events. Eighteen participants volunteered for this study, and these were randomly assigned to either a morning training group (MTG, who trained only between 07:00 and 08:00 h, n = 6), an evening training group (ETG, who trained only between 17:00 and 18:00 h, n = 6), or a control group (CG, did not train but participated in all tests, n = 6). Swimming performance and technical ability – (i) stroke parameters: swim velocity (V), stroke rate (SR), and stroke length (SL); and (ii) motor organization: arm stroke phases and arm coordination (Idc) – were recorded 2 weeks before and 2 weeks after an 8-week regular training period. For all participants, the morning and evening tests were scheduled at the same time of day as the morning and evening training sessions. After training, the major finding of this study was that both ETG and the CG showed significantly lower P, V, SR, phase (B), phase (C), and Idc values in the morning than in the evening. However, P, V, SR, phase (B), phase (C), and Idc of the MTG measured at 07:00 and 17:00 h did not differ. Thus, training at a specific time of day increased performance in MTG at this time and modified the diurnal variation of swim performance. This study indicates that training at a specific time of day can result in marked changes in both swimming performance and technical aspects of swimming. Furthermore, training in the morning improved morning swimming performance and its components, and the amplitude of the morning–evening difference decreased. Training in the evening improved swimming performance and its components more in the evening than the morning, and the amplitude of the morning–evening difference increased.     

Effect of Time‐of‐Day‐Specific Strength Training on Serum Hormone Concentrations and Isometric Strength in Men

A time‐of‐day influence on the neuromuscular response to strength training has been previously reported. However, no scientific study has examined the influence of the time of day when strength training is performed on hormonal adaptations. Therefore, the primary purpose of this study was to examine the effects of time‐of‐day‐specific strength training on resting serum concentrations and diurnal patterns of testosterone (T) and cortisol (CORT) as well as maximum isometric strength of knee extensors. Thirty eight diurnally active healthy, previously untrained men (age 20–45 yrs) underwent a ten‐week preparatory strength training period when sessions were conducted between 17:00–19:00 h. Thereafter, these subjects were randomized into either a morning (n=20, training times 07:00–09:00 h) or afternoon (n=18, 7:00–19:00 h) training group for another ten‐week period of time‐of‐day‐specific training (TST). Isometric unilateral knee extension peak torque (MVC) was measured at 07:00, 12:00, 17:00, and 20:30 h over two consecutive days (Day 1 & Day 2) before and after TST. Blood samples were obtained before each clock‐time measurement to assess resting serum T and CORT concentrations. A matched control group (n=11) did not train but participated in the tests. Serum T and CORT concentrations significantly declined from 07:00 to 20:30 h on all test days (Time effect, p<.001). Serum CORT at 07:00 h was significantly higher on Day 1 than Day 2 in the control and afternoon group, both in Pre and Post conditions (Day×Time interaction, p<.01). In the morning group, a similar day‐to‐day difference was present in the Pre but not Post conditions (Time×Group interaction, p<.05). MVC significantly increased after TST in both the morning and afternoon groups (Pre to Post effect, p<.001). In both groups, a typical diurnal variation in MVC (Time effect, p<.001) was found, especially on Day 2 in the Pre condition, and this feature persisted from Pre to Post in the afternoon group. In the morning group, however, diurnal variation was reduced after TST on both Day 1 and Day 2 (Pre to Post×Day×Time×Group interaction, p<.05). In conclusion, 10 weeks of morning time‐of‐day‐specific strength training resulted in reduced morning resting CORT concentrations, presumably as a result of decreased masking effects of anticipatory psychological stress prior to the morning testing. The typical diurnal pattern of maximum isometric strength was blunted by the TST period in the morning but not the afternoon group. However, the TST period had no significant effect on the resting total T concentration and its diurnal pattern and on the absolute increase in maximum strength.     

The effects of time of day-specific resistance training on adaptations in skeletal muscle hypertrophy and muscle strength: A systematic review and meta-analysis

The present paper endeavored to elucidate the topic on the effects of morning versus evening resistance training on muscle strength and hypertrophy by conducting a systematic review and a meta-analysis of studies that examined time of day-specific resistance training. This systematic review was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines with searches conducted through PubMed/MEDLINE, Scopus, and SPORTDiscus databases. The Downs and Black checklist was used for the assessment of the methodological quality of the included studies. Studies that examined the effects of time of day-specific resistance training (while equating all other training variables, such as training frequency and volume, between the groups) on muscle strength and/or muscle size were included in the present review. The random effects model was used for the meta-analysis. Meta-analyses explored (1) the differences in strength expression between morning and evening hours at baseline; (2) the differences in strength within the groups training in the morning and evening by using their post-intervention strength data from the morning and evening strength assessments; (3) the overall differences between the effects of morning and evening resistance training (with subgroup analyses conducted for studies that assessed strength in the morning hours and for the studies that assessed strength in the evening hours). Finally, a meta-analysis was also conducted for studies that assessed muscle hypertrophy. Eleven studies of moderate and good methodological quality were included in the present review. The primary findings of the review are as follows: (1) at baseline, a significant difference in strength between morning and evening is evident, with greater strength observed in the evening hours; (2) resistance training in the morning hours may increase strength assessed in the morning to similar levels as strength assessed in the evening; (3) training in the evening hours, however, maintains the general difference in strength across the day, with greater strength observed in the evening hours; (4) when comparing the effects between the groups training in the morning versus in the evening hours, increases in strength are similar in both groups, regardless of the time of day at which strength assessment is conducted; and (5) increases in muscle size are similar irrespective of the time of day at which the training is performed.     

INTERACTIONS OF CORTISOL,TESTOSTERONE, AND RESISTANCE TRAINING: INFLUENCE OF CIRCADIAN RHYTHMS

Diurnal variation of sports performance usually peaks in the late afternoon, coinciding with increased body temperature. This circadian pattern of performance may be explained by the effect of increased core temperature on peripheral mechanisms, as neural drive does not appear to exhibit nycthemeral variation. This typical diurnal regularity has been reported in a variety of physical activities spanning the energy systems, from Adenosine triphosphate-phosphocreatine (ATP-PC) to anaerobic and aerobic metabolism, and is evident across all muscle contractions (eccentric, isometric, concentric) in a large number of muscle groups. Increased nerve conduction velocity, joint suppleness, increased muscular blood flow, improvements of glycogenolysis and glycolysis, increased environmental temperature, and preferential meteorological conditions may all contribute to diurnal variation in physical performance. However, the diurnal variation in strength performance can be blunted by a repeated-morning resistance training protocol. Optimal adaptations to resistance training (muscle hypertrophy and strength increases) also seem to occur in the late afternoon, which is interesting, since cortisol and, particularly, testosterone (T) concentrations are higher in the morning. T has repeatedly been linked with resistance training adaptation, and higher concentrations appear preferential. This has been determined by suppression of endogenous production and exogenous supplementation. However, the cortisol (C)/T ratio may indicate the catabolic/anabolic environment of an organism due to their roles in protein degradation and protein synthesis, respectively. The morning elevated T level (seen as beneficial to achieve muscle hypertrophy) may be counteracted by the morning elevated C level and, therefore, protein degradation. Although T levels are higher in the morning, an increased resistance exercise–induced T response has been found in the late afternoon, suggesting greater responsiveness of the hypothalamo-pituitary-testicular axis then. Individual responsiveness has also been observed, with some participants experiencing greater hypertrophy and strength increases in response to strength protocols, whereas others respond preferentially to power, hypertrophy, or strength endurance protocols dependent on which protocol elicited the greatest T response. It appears that physical performance is dependent on a number of endogenous time-dependent factors, which may be masked or confounded by exogenous circadian factors. Strength performance without time-of-day–specific training seems to elicit the typical diurnal pattern, as does resistance training adaptations. The implications for this are (a) athletes are advised to coincide training times with performance times, and (b) individuals may experience greater hypertrophy and strength gains when resistance training protocols are designed dependent on individual T response. (Author correspondence: Lawrence.hayes@uws.ac.uk)     

Diurnal patterns of airborne pollen concentration of the selected tree and herb taxa in Gdańsk (northern Poland)

The diurnal variation of airborne pollen concentrations of Alnus, Betula, Pinus, Poaceae, Urtica and Artemisia was examined at the sampling station in Gdańsk, northern Poland. Diurnal patterns of Alnus and Pinus pollen show distinctly lower values and low frequency of diurnal maxima between midnight and late morning and a clear rise of pollen counts at around noon. The rather high values remain during the afternoon and evening. The Betula pollen counts are almost evenly distributed along day and night and diurnal maxima appear in similar frequency at any time of day. Pollen concentrations of Poaceae increase at about 9.00 hours and remain high till late evening. Diurnal patterns of Urtica and Artemisia show very clear variation with high peaks at around 9.00 hours (Artemisia) and 13.00 hours (Urtica). The comparison of the data from Gdańsk with the data from other aerobiological stations shows very similar general features in the diurnal patterns irrespective the region or the local situation.     

VARIATIONS IN FLORIDOSIDE CONTENT AND FLORIDOSIDE PHOSPHATE SYNTHASE ACTIVITY IN PORPHYRA PERFORATA (RHODOPHYTA)1

The diurnal and seasonal variations in floridoside content and floridoside phosphate synthase (FPS) activity were measured in samples of Porphyra perforata J. Ag. growing in the field. Floridoside content generally increased about fourfold from early morning to the middle of the day and then dropped gradually in the afternoon and the evening. On a monthly basis, there was a steady increase in floridoside content from February to May. A similar trend in monthly increase in FPS activity was also observed from February to April. The level of FPS activity varied with the time of day. The highest activity was observed early in the morning shortly after dawn; subsequently, it decreased, reaching about 50% of the peak value late in the afternoon/evening. On a daily as well as seasonal basis, a change in FPS activity correlated with a change in floridoside content. Among environmental factors, floridoside content and FPS activity showed a positive correlation with daylength and temperature on a seasonal basis. However, on a daily basis, salinity and water temperature did not seem to affect the floridoside content or the FPS activity.     

Diurnal Profiles of Serum Triiodothyronine and Thyroxine Levels: A Study in Male Roseringed Parakeets (Psittacula krameri) Following Exogenous Administration of Melatonin

This study demonstrates that under subtropical environmental conditions the circulating levels of triiodothyronine (T 3 ) and thyroxine (T 4 ) in adult male roseringed parakeets undergo parallel changes according to a diurnal cycle with a trough in the early morning and a peak in the evening. Chronic afternoon administration of melatonin (25 µg/ 100 g body wt./ day for 30 consecutive days) abolishes time-bound changes in the concentrations of T 3 by suppressing its evening peak, but does not abolish the diurnal rhythm of T 4 . Exogenous melatonin, however, causes a significant increase in the evening value of serum T 4 and a decrease in its value at midnight resulting in phase-shifting of the diurnal fluctuations of T 4 compared to that in the control birds. It appears that exogenous melatonin can alter the diurnal profiles of serum thyroid hormones in a wild psittacine bird.     

Diurnal Profiles of Serum Triiodothyronine and Thyroxine Levels: A Study in Male Roseringed Parakeets (Psittacula krameri) Following Exogenous Administration of Melatonin

This study demonstrates that under subtropical environmental conditions the circulating levels of triiodothyronine (T 3) and thyroxine (T 4) in adult male roseringed parakeets undergo parallel changes according to a diurnal cycle with a trough in the early morning and a peak in the evening. Chronic afternoon administration of melatonin (25 µg/ 100 g body wt./ day for 30 consecutive days) abolishes time-bound changes in the concentrations of T 3 by suppressing its evening peak, but does not abolish the diurnal rhythm of T 4. Exogenous melatonin, however, causes a significant increase in the evening value of serum T 4 and a decrease in its value at midnight resulting in phase-shifting of the diurnal fluctuations of T 4 compared to that in the control birds. It appears that exogenous melatonin can alter the diurnal profiles of serum thyroid hormones in a wild psittacine bird.     

Effects of prolonged and reduced warm-ups on diurnal variation in body temperature and swim performance

Previous studies have suggested a diurnal variation in the performance of physical tasks. The theoretical basis for the effect of time-of-day on performance centers on the circadian rhythms of many physiological variables and especially the body temperature curve. This investigation had two purposes: (a) to determine if increasing the volume of the warm-up could eliminate diurnal variation in body temperature and swim performance, and (b) to determine if reduction of the warm-up volume in the late afternoon would affect body temperature and swim performance. Participants for this investigation included 6 male and 4 female competitive swimmers (mean age = 15 +/- 1 years). Before the swim performance trials in the morning, participants warmed up with either standard volume (2,011.68 m) or 200% of that volume. Before the afternoon swim performance trials, warm-up volumes were either 33% or 100% of the standard warm-up volume. Before entering the water and immediately after the warm-up, temperature was taken from the ear. After the swim performance, participants were asked to rate their perceived exertion on the basis of Borg's CR-10 rating scale. The order of test administration for time of day and warm-up condition was balanced and with tests carried out over 4 days. Each swimmer completed 1 test condition (warm-up) per day. Results indicated that increased morning warm-up time eliminated diurnal variation in body temperature; however, evening superiority in swimming performance was not eliminated. The results also indicated that reducing the volume of the afternoon warm-up to 33% of the standard warm-up had no effect on body temperature or swim performance.     

Effect of time-of-day-specific strength training on serum hormone concentrations and isometric strength in men

A time-of-day influence on the neuromuscular response to strength training has been previously reported. However, no scientific study has examined the influence of the time of day when strength training is performed on hormonal adaptations. Therefore, the primary purpose of this study was to examine the effects of time-of-day-specific strength training on resting serum concentrations and diurnal patterns of testosterone (T) and cortisol (CORT) as well as maximum isometric strength of knee extensors. Thirty eight diurnally active healthy, previously untrained men (age 20-45 yrs) underwent a ten-week preparatory strength training period when sessions were conducted between 17:00-19:00 h. Thereafter, these subjects were randomized into either a morning (n=20, training times 07:00-09:00 h) or afternoon (n=18, 7:00-19:00 h) training group for another ten-week period of time-of-day-specific training (TST). Isometric unilateral knee extension peak torque (MVC) was measured at 07:00, 12:00, 17:00, and 20:30 h over two consecutive days (Day 1 & Day 2) before and after TST. Blood samples were obtained before each clock-time measurement to assess resting serum T and CORT concentrations. A matched control group (n=11) did not train but participated in the tests. Serum T and CORT concentrations significantly declined from 07:00 to 20:30 h on all test days (Time effect, p<.001). Serum CORT at 07:00 h was significantly higher on Day 1 than Day 2 in the control and afternoon group, both in Pre and Post conditions (Day x Time interaction, p<.01). In the morning group, a similar day-to-day difference was present in the Pre but not Post conditions (Time x Group interaction, p<.05). MVC significantly increased after TST in both the morning and afternoon groups (Pre to Post effect, p<.001). In both groups, a typical diurnal variation in MVC (Time effect, p<.001) was found, especially on Day 2 in the Pre condition, and this feature persisted from Pre to Post in the afternoon group. In the morning group, however, diurnal variation was reduced after TST on both Day 1 and Day 2 (Pre to PostxDay x TimexGroup interaction, p<.05). In conclusion, 10 weeks of morning time-of-day-specific strength training resulted in reduced morning resting CORT concentrations, presumably as a result of decreased masking effects of anticipatory psychological stress prior to the morning testing. The typical diurnal pattern of maximum isometric strength was blunted by the TST period in the morning but not the afternoon group. However, the TST period had no significant effect on the resting total T concentration and its diurnal pattern and on the absolute increase in maximum strength.     

Short-term temporal dynamics of yeast abundance on the tall fescue phylloplane

Six replicate trials were conducted to determine the short-term temporal dynamics and the effects of foliar applications of nutrients on the phylloplane yeast community of tall fescue (Festuca arundinacea Schreb.). In each trial, 2% sucrose + 0.5% yeast extract solution or sterile deionized water (control) was applied to the experiment plots. Twelve hours post-treatment (at 0600 hours), leaf samples were collected and yeast colony-forming units (cfu) were enumerated by dilution plating. This process was repeated at 1200, 1800, and 2400 hours in each trial. Significant differences were observed between the number of yeast cfu and the time at which the samples were collected. On average, the number of yeast cfu recovered was significantly less at 1800 hours and significantly greatest at 2400 hours when compared with all other sampling times. Averaged over all time intervals, we observed a trend of increased yeast abundance in turf treated with the nutrient solution compared with control treatments. In a separate investigation, atmospheric yeast abundance above the canopy of tall fescue was assessed in the morning (0900) and in the afternoon (1500) using a Thermo Andersen single stage viable particle sampler. In 5 of the 6 trials of this experiment, atmospheric yeast abundance was significantly greater in the morning than in the afternoon. Results suggest the following colonization model: phylloplane yeasts on tall fescue reproduce during the late evening and early morning, stabilize during the late morning and early afternoon through exchange of immigrants and emigrants, and decline during the late afternoon and (or) early evening.     

Evidence of daily spawning in natural populations of the New Zealand snapper Pagrus auratus (Sparidae)

Synopsis New Zealand snapper, Pagrus auratus, were captured by trawling from NE New Zealand over two successive spawning seasons, and examined for acute temporal changes in gonad condition. Fish with oocytes completing final oocyte maturation predominated during the morning, with a peak in ovulated fish occurring just after midday. Afternoon catches were dominated by fish in which the most advanced oocytes had yet to begin final maturation. This suggests that ovulation is synchronised to occur soon after midday, and the high proportion (up to 100% of the catch) of fish with particular gonad stages captured at any one time indicates that daily spawning involves most of the population. Diurnal changes in oocyte diameter support a daily spawning rhythm, with numbers of large hydrated oocytes peaking in the late morning, followed by the disappearance of these oocyte stages in the afternoon. Snapper captured alive by longlining were returned to the laboratory to examine the relationship between ovulation and probable time of spawning. Unovulated fish generally ovulated close to midday on the day of capture (morning captures), or the following day (afternoon captures). The viability of ovulated eggs (proportion undergoing division after fertilization) decreased markedly after oviduct residence times of over 8 hours. This suggests that natural spawning occurs before the late evening. The results of this study are consistent with anecdotal evidence suggesting that spawning occurs every day during the late afternoon or early evening, and is similar to the reproductive patterns displayed by a number of closely related sparids. Department of Zoology, University of Otago, PO Box 56, Dunedin, New Zealand     

Effects of Waking Time and Breakfast Intake Prior to Evaluation of Psychomotor Performance in the Early Morning

Many studies conducted in the field of chronobiology report diurnal fluctuation in cognitive and physical performance that occurs in phase with the body temperature circadian rhythm. Waking time and whether or not breakfast is consumed are currently considered to influence the diurnal fluctuation in data collected in the morning at 06∶00 h and evening at 18∶00 h. Nineteen male subjects participated in four test sessions to examine if wake‐up time (04∶00 h or 05∶00 h) and eating or not eating breakfast influence psychomotor performance capacity at 06∶00 h. All four sessions were separated by ≥36 h and were completed in a counterbalanced order. Each test session comprised sign cancellation, Epworth Sleepiness Scale, simple reaction time, and manual dexterity tests. Most of the results indicate that psychomotor performance when evaluated at 06∶00 h under each of the four different study situations (two waking times and two breakfast conditions) is not statistically significantly different. Consequently, previous results that documented diurnal fluctuations in morning and evening performance capacities, with test sessions at 06∶00 h, are confirmed. Being less efficient in the early morning than in the afternoon potentially exposes people to elevated risk of accident and injury at this time of the day. Prior waking time and/or consumption of a light meal, plus other countermeasures mentioned in the literature, are insufficient to prevent this risk.     

Diurnal rhythms of thyroid hormones in rooster chicks (Gallus domesticus). 1. Studies on the colloid epithelium portion, the radioiodine accumulation in the thyroid gland and the plasma radioiodide concentration]

Four and five week old White Leghorn cockerels were investigated concerning diurnal changes of thyroidal activity. They were kept under normal conditions, including the changes in day light (light from 5.00 am to 8.00 pm). In the thyroid maxima of the per cent amount of colloid were found at 3.00 am and at noon. The values differed significantly from the intermediate ones (2P less than 0.001) which reached only 22 per cent of the maxima. The thyroidal uptake of radioiodine had also a maximum at 3.00 am (51 percent and 78 percent resp., 90 min. or 24 hours p.i.). The 24-h uptake at 3.00 am was significant different from the corresponding uptakes between 6.00 am and 6.00 pm (53-61 percent; 2P less than 0.05). The plasma radioiodide increased at afternoon and in the evening. The 9.00 pm concentration differed significantly from the 9.00 am concentration (2P less than 0.001). Since in the afternoon most of the food is ingested the thyroid can take up a greater amount of untracered iodide and therefore the radioiodide concentration of plasma may remain high. The above observations may be explained in the following way: (1) The thyroidal iodine uptake is increased in the afternoon corresponding to the increase in colloid; however these increase is not detectable by measuring the radioiodine uptake because of dilution effects (during the night the increase in colloid coincidences with the increase in iodine uptake); (2) looking at the daily changes of colloid and radioiodine uptake the thyroid may be stimulated in the early morning and in the evening.     

Wise “birds” follow their clock: The role of emotional intelligence and morningness–eveningness in diurnal regulation of mood

Emotional intelligence (EI) and morningness–eveningness (M-E) preference have been shown to influence mood states. The present article investigates the way in which these two constructs may interact, influencing morning and evening mood levels. A sample of 172 participants completed a multidimensional mood scale measuring energetic arousal (EA), tense arousal (TA), and hedonic tone at 7:00 and at 22:00. As expected, morning and evening types experienced higher EA at their preferred time of day; effects of M-E on other mood dimensions were weaker. EI was found to correlate with lower TA, but the association was stronger at 22:00, perhaps reflecting the role of EI in managing the social events characteristic for the evening hours. An interactive effect of EI and M-E was found for both diurnal changes and morning levels of EA. Namely, in individuals higher in EI, there appeared a more marked synchrony effect between chronotype and EA, which was absent in those low in EI; individuals higher in EI showed more pronounced diurnal changes in EA characteristic for their chronotype (i.e., higher EA at morning hours in morning chronotypes; higher EA at evening hours in evening chronotypes), while in participants low in EI, diurnal changes in EA were smaller. Moreover, the characteristic positive association between morningness and EA during morning hours was apparent only in those high in EI. These findings suggest that individual differences in circadian variation in mood reflect several factors, including an endogenous rhythm in energy, the distribution of social activities throughout the day, and the person’s awareness of their own energy level.     

Migratory restlessness in the Yellow-faced Honeyeater Lichenostomus chrysops(Meliphagidae), an Australian diurnal migrant

The Yellow-faced Honeyeater Lichenostomus chrysops is a diurnal migrant which covers short to moderate distances in eastern Australia. Recordings of locomotor activity of nine wild-caught Yellow-faced Honeyeaters kept under a simulated natural photoperiod in the laboratory over a period of 13 months showed that these birds exhibit a distinct seasonal pattern in hopping activity. Two major seasonal peaks of enhanced activity were observed. The first occurred during the time of autumn migration in March to July, while a second peak from September to December coincided roughly with spring migration. Daily activity patterns of Yellow-faced Honeyeaters showed two major peaks. The first peak ranged from the early morning hours to approximately early afternoon, while a second smaller peak was observed in the late afternoon. During their migratory periods in spring and autumn, the morning as well as the afternoon peaks were considerably higher than in months when Yellow-faced Honeyeaters do not migrate.     

Effects of morning vs. evening combined strength and endurance training on physical performance,sleep and well-being

The aim of the present study was to examine how combined strength and endurance training in the morning and evening influences the adaptations in strength and endurance performance, perception of time management, psychological well-being and sleep. The combined training period lasted for 24 weeks and the participants were divided into the morning training (MG, n = 18), evening training (EG, n = 24) and control groups (CG, n = 10). Isometric leg press force (iLP), maximal oxygen consumption (VO₂max), sleep behavior, fatigue, time management, motivation, self-esteem and health-related quality of life (HRQoL) were assessed. Morning to evening difference in iLP was observed in both MG and EG at Pre and Post, with higher force values in the evening, but not for VO₂max. iLP force increased significantly in EG in the morning (p < 0.001) and evening (p = 0.010). VO₂max increased in MG and EG both in the morning (both p < 0.001) and in the evening (MG: p < 0.001; EG: p = 0.003). Participants of the present study slept 7–8 h per night and the self-reported sleep duration, get-up time and the average time to go to bed were similar between the groups and did not change from Pre to Post. From HRQoL dimensions, the score for bodily pain decreased in MG (p = 0.029) and significant between-group differences were observed for Pre-Post changes in MG and EG (p = 0.001) as well as between MG and CG (p < 0.001). In vitality, a significant between-group difference was observed for Pre to Post changes in MG and EG (p = 0.014). Perception of time management decreased in EG (p = 0.042) but stayed unchanged for MG and CG. For the intrinsic motivation to participate, significant between-group differences were observed for MG and EG (p = 0.033) and between MG and CG (p = 0.032) for Pre to Post changes. Self-esteem improved in MG (p = 0.029) and EG (p = 0.024). The present combined strength and endurance training program performed in the morning and in the evening led to similar improvements in strength and endurance performance. Training in the morning or in the evening did not disrupt the already good sleep behavior and it was able to further increase the self-esteem. Although training in the morning hours may leave more time for free time activities or social life (i.e. family and friends) compared to the evening training, it might be more challenging to stay motivated to participate in prolonged training programs in the morning hours.