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.     

Post-resistance training detraining: time-of-day effects on training and testing outcomes

The aim of this study was to examine the effects of 3 and 5 weeks of detraining after 14 weeks of resistance training at a specific time of day on performances during the squat jump (SJ) and the maximal voluntary contraction (MVC). Thirty-one healthy male physical education students (age: 23.1 ± 1.0 years; height: 176.1 ± 6.3 cm; weight: 74.9 ± 10.9 kg) were randomly assigned to either a morning training group (MTG, training between 07:00 and 08:00 h, n = 10), an evening training group (ETG, training between 17:00 and 18:00 h, n = 11) or a control group (CG, no training, n = 10). Participants then performed eight test sessions (twice per day, at 07:00 and 17:00 h) over the course of four phases: during pre-training, immediately post-training, and after 3 and 5 weeks of detraining. Before each test session, oral temperature was recorded. During the first 12 weeks of resistance training, participants performed 3 sets of 10 repetitions to failure (10-RM) for 4 exercises (squat, leg press, leg extension and leg curl, with 2 min of recovery between each exercise); during the last two weeks, training intensity increased to 8-RM with 3 min of recovery between each exercise. Oral temperature was significantly higher at 17:00 than 07:00 h during all test periods (p < 0.05). Likewise, SJ and MVC performances were significantly higher at 17:00 h than 07:00 h during all four test days in ETG and CG, and before training and 3 and 5 weeks after training in MTG (p < 0.05). For both training groups, most SJ and MVC performances (except MTG at 07:00 h and ETG at 17:00 h) returned to baseline values after 5, but not after 3, weeks of detraining. This study showed that 14 weeks of training at a specific time of day blunted the diurnal variation of MVC and SJ in the MTG. The improvement in performance brought about by resistance training was partially retained after 3 weeks of detraining (unless training had taken place at a non-habitual time of day) but was lost after 5 weeks of detraining. There was no effect of the time of training on core temperature.     

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 strength training by electrostimulation at a specific time of day on immune response and anaerobic performances during short-term maximal exercise

The aim of this study was to evaluate the effect of electrostimulation strength training (ES) and time-of-day on immune response and anaerobic performances during short-term maximal exercise. In randomized order, 24 active men divided into three groups: MTG (n=8): training times 07:00–08:00h; ETG (n=8): training times 17:00–18:00h; and CG (n=8) and were asked to perform a 30-s Wingate test (i.e. peak (PP), mean (MP)) and strength (1-RM) before (T0) and after four weeks of training (T1) at 08:00h and 18:00h. Our results showed that oral temperature, PP (p<0.05), MP (p<0.05), and Interleukine-6 levels (IL-6) (p<0.001) were significantly higher at 18:00h compared to 08:00h in all groups. However, 1-RM was not affected by the time-of-day (p>0.05). Likewise, IL-6 increased after exercise at T0 and T1 in CG, ETG, and MTG (p<0.001). Moreover, ES training leads an improvement in performances (p<0.05) with an increase in the tight circumference for the MTG (p<0.01) at the same time-of-training (08:00h) without affecting the immune response (p>0.05). In fact, the amplitude of variation was disappeared in MTG after ES. However, the ES did not affect the PP, MP, and 1-RM in ETG with no change in the tight circumference. A significant increase in IL-6 at the same time-of-training (p<0.05) was observed on ETG. For CG, no significant change was observed after ES compared with pre-training. In conclusion, ES training in the morning is a potent strategy to counteract the decrease in anaerobic performances without affecting inflammatory response compared to the evening training.     

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.     

Effect of time of day on line-bisecting performance in female soccer players

The purpose of this study was to examine the effect of time of day on visuospatial attention in trained subjects. We used the line-bisecting task. The protocol involved 30 healthy volunteer female soccer players (age: 21.1 ± 2.1 years, level of experience: 8.1 ± 3.2 years, height: 1.7 ± 0.03 cm, weight: 59.2 ± 3.49 kg). They performed two-test sessions at different times of day, 8:00 am and 8:00 pm. The results showed a significant time-of-day effect on line-bisecting performance, with a better precision in the evening than in the morning. The rightward error observed in the morning was reversed in the evening. An interaction between time of day x length was also observed, indicating that the difference in performance between the morning and the evening increased with the length of the line. We conclude that activities that require better visuospatial performance should be programed to take place in the evening.     

Effect of time of day on the offensive capability and aerobic performance in football game

The purpose of this study was to examine the time-of-day effects on the offensive capability and aerobic performance in football game in young subjects. In a randomized order, participants realized the Yo–Yo intermittent recovery test in two test sessions and a football game situations (two 15-min games), interspersed by a verbalization sequence (3 min) at 08:00 and 17:00 h on separate days. A recovery period of 24 h was permitted between two consecutive test sessions. The results revealed diurnal variations on the maximal aerobic velocity during the Yo–Yo test (MAV) and the oral temperature with higher values in the afternoon than morning (p < 0.05). Concerning offensive capability, the numbers of scored goals were significantly higher at 17:00 h in comparison with 08:00 h (p < 0.05). However, there was no significant difference between 08:00 and 17:00 h for the kicked balls (shooting parameter). In conclusion, our findings suggest that performance was improved in the evening and the parameters (shooting and Scored goals) can be used as a model to describe the offensive capacity in football game depending on the time of day.     

Morning Versus Evening Power Output and Repeated‐Sprint Ability

We investigated the effect of time‐of‐day on both maximal sprint power and repeated‐sprint ability (RSA). Nine volunteers (22±4 yrs) performed a RSA test both in the morning (07:00 to 09:00 h) and evening (17:00 to 19:00 h) on different days in a random order. The RSA cycle test consisted of five, 6 sec maximal sprints interspersed by 24 sec of passive recovery. Both blood lactate concentration and heart rate were higher in the evening than morning RSA (lactate values post exercise: 13±3 versus 11±3 mmol/L^?1, p<0.05). The peak power developed during the first sprint was higher in the evening than morning (958±112 vs. 915±133 W, p<0.05), but this difference was not apparent in subsequent sprints, leading to a higher power decrement across the 5×6 sec test in the evening (11±2 vs. 7±3%, p<0.05). Both the total work during the RSA cycle test and the power developed during bouts 2 to 5 failed to be influenced by time‐of‐day. This suggests that the beneficial effect of time‐of‐day may be limited to a single expression of muscular power and fails to advantage performance during repeated sprints.     

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.     

Effects of chronotype and time of day on mood responses to CrossFit training

Morningness-eveningness, time of day, and physical exercises have been shown to influence mood states. This study aimed to test whether impact of physical exercise on mood depends on time of day and chronotype. Ninety-four participants (age 32 ± 6 years; 34% females; weekly training volume 4 ± 1 hours) filled the Composite Scale of Morningness and reported their current mood using the UWIST Mood Adjective Checklist before and after a 60-min long CrossFit training session which took part in the morning (beginning at 6:30 or 7:45) or in the evening (beginning at 19:30 or 20:45). In this quasi-experiment the measurements were taken by the occasion of the participants’ usual training, in their preferred hours. There were only a few evening-types in the studied sample, while morning and intermediate chronotypes were over-represented. Participation in CrossFit training resulted in mood improvement consisting of increase in energetic arousal (η² = 0.29) and hedonic tone (η² = 0.47) and reduction of tense arousal (η² = 0.14), all significant at p = 0.001. Furthermore, CrossFit training during morning hours boosted mood in the intermediate/evening chronotype group to the levels observed in morning chronotypes (η² = 0.29, p < 0.05, for the three-way interaction effect). We conclude that participation in intense physical exercise, such as CrossFit training, may allow compensation for the negative effects of non-optimal time of day on experienced moods, particularly in the case of neither/evening-types.     

Diurnal variation in repeated sprint performance cannot be offset when rectal and muscle temperatures are at optimal levels (38.5°C)

The present study investigated whether increasing morning rectal temperatures (T_rec) to evening levels, or increasing morning and evening T_rec to an “optimal” level (38.5°C), resulting in increased muscle temperatures (T_m), would offset diurnal variation in repeated sprint (RS) performance in a causal manner. Twelve trained males underwent five sessions [age (mean ± SD) 21.0 ± 2.3 years, maximal oxygen consumption (V?O₂max) 60.0 ± 4.4 mL.kg^–1 min^–1, height 1.79 ± 0.06 m, body mass 78.2 ± 11.8 kg]. These included control morning (M, 07:30 h) and evening (E, 17:30 h) sessions (5-min warm-up), and three further sessions consisting of a warm-up morning trial (M_E, in 39–40°C water) until T_rec reached evening levels; two “optimal” trials in the morning and evening (M_38.5 and E_38.5, in 39–40°C water) respectively, until T_rec reached 38.5°C. All sessions included 3 × 3-s task-specific warm-up sprints, thereafter 10 × 3-s RS with 30-s recoveries were performed a non-motorised treadmill. T_rec and T_m measurements were taken at the start of the protocol and following the warm-up periods. Values for T_rec and T_m at rest were higher in the evening compared to morning values (0.48°C and 0.69°C, p < 0.0005). RS performance was lower (7.8–8.3%) in the M for distance covered (DC; p = 0.002), average power (AP; p = 0.029) and average velocity (AV; p = 0.002). Increasing T_rec in the morning to evening values or optimal values (38.5°C) did not increase RS performance to evening levels (p = 1.000). However, increasing T_rec in the evening to “optimal” level through a passive warm-up significantly reduced DC (p = 0.008), AP (p < 0.0005) and AV (p = 0.007) to values found in the M condition (6.0–6.9%). Diurnal variation in T_rec and T_m is not wholly accountable for time-of-day oscillations in RS performance on a non-motorised treadmill; the exact mechanism(s) for a causal link between central temperature and human performance are still unclear and require more research.     

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.     

Daily Changes in the Competence for Photo- and Gravitropic Response by Potato Plantlets

Competence for phototropic (PT) and gravitropic (GT) bending by potato plantlets grown in vitro manifests regular daily changes indicating possible involvement of circadian regulation. Unilateral stimulation of plantlets with blue light at dawn resulted in moderate PT response regarding both attained curvature and long lag phase. The PT response was the strongest between 8:00 and 12:00 h. Throughout the afternoon and in the evening, bending rate and maximal PT curvature declined significantly until 23:00 h. The GT response was fastest and strongest for plantlets stimulated early in the morning and late in the evening. During the rest of the day, GT competence did not change much apart from a minimum at 15:00. In conditions comprising either prolonged day or prolonged night, plantlets appeared to maintain rhythmicity of competence for PT and GT at least in the short-term. Introduction of a dark period prior to the tropic stimulation at 11:00 h when both PT and GT responses were strong resulted in the opposite effect: PT was depressed, and GT was enhanced. There was a time threshold of 60 min for the duration of the dark period so the plants can sense interruption in the daylight. Levels of relative expression of a PHOT2 gene indicate rhythmic daily changes. The PHOT2 gene was present at high levels during morning hours and late in the evening. As the mid-day and the afternoon hours approached, PHOT2 expression decreased and reached a daily minimum at 17:00 h. We believe that our data offer strong support for the conclusion that there is an involvement of circadian rhythms in control of both PT and GT.     

Opuntia ficus-indica juice supplementation: what role it plays on diurnal variation of short-term maximal exercise?

The aim of this study was to investigate the effect of natural Opuntia ficus-indica juice (OFIJ) supplementation on anaerobic performance at two times of day. Twenty-two healthy male subjects (20.91 ± 1.22; 21.00 ± 0.84 years) divided into two groups: Experimental group (EG: n = 11) and a control group (CG: n = 11) performed two tests-sessions (30-s of Wingate test (i.e. Peak power (PP), Mean power (MP)), Sargent jump test (SJT), sprint 10 m), before and after natural OFIJ supplementation at 07:00 h and 17:00 h. T-test showed that the OFIJ has a potent antioxidant capacity for capturing free radicals following the 22-diphenyl-1-picrylhydrazyl (DPPH^●) test (p < 0.05). Likewise, the ANOVA revealed that anaerobic performances were significantly higher at 17:00 h compared to 07:00 h around the peak of the temperature (p < 0.05) in both EG and CG before supplementation. Moreover, OFIJ lead an improvement of performances with (+2.09% at 07:00 h vs.+9.36% 17:00 h) for PP, (+11.29% at 07:00 h vs.+11.77% 17:00 h) for MP, (+9.42% at 07:00 h vs.+7.63% 17:00 h) for SJT in EG. The RPE scores on response to the Wingate test decrease after OFIJ supplementation (p < 0.01). For the sprint values, a significant improvement was after OFIJ (?7.10% at 07:00 h vs. ?6.45% 17:00 h). However, no change was observed for CG after supplementation. In conclusion, the natural OFIJ supplementation for two weeks appears to ameliorate the performance upon two times of day with great improvement observed in the evening during short-term maximal exercise given the higher muscle damage, inflammatory, and oxidative responses at this time of day. Thus, it’s necessary that athletes, coaches, and medical staff consider the positive effects of Opuntia ficus-indica to improve anaerobic performance.     

Bright-light exposure during daytime sleeping affects nocturnal melatonin secretion after simulated night work

The guidelines for night and shift workers recommend that after night work, they should sleep in a dark environment during the daytime. However, staying in a dark environment during the daytime reduces nocturnal melatonin secretion and delays its onset. Daytime bright-light exposure after night work is important for melatonin synthesis the subsequent night and for maintaining the circadian rhythms. However, it is not clear whether daytime sleeping after night work should be in a dim- or a bright-light environment for maintaining melatonin secretion. The aim of this study, therefore, was to evaluate the effect of bright-light exposure during daytime sleeping on nocturnal melatonin secretion after simulated night work. Twelve healthy male subjects, aged 24.8 ± 4.6 (mean ± SD), participated in 3-day sessions under two experimental conditions, bright light or dim light, in a random order. On the first day, the subjects entered the experimental room at 16:00 and saliva samples were collected every hour between 18:00 and 00:00 under dim-light conditions. Between 00:00 and 08:00, they participated in tasks that simulated night work. At 10:00 the next morning, they slept for 6 hours under either a bright-light condition (>3000 lx) or a dim-light condition (<50 lx). In the evening, saliva samples were collected as on the first day. The saliva samples were analyzed for melatonin concentration. Activity and sleep times were recorded by a wrist device worn throughout the experiment. In the statistical analysis, the time courses of melatonin concentration were compared between the two conditions by three-way repeated measurements ANOVA (light condition, day and time of day). The change in dim light melatonin onset (ΔDLMO) between the first and second days, and daytime and nocturnal sleep parameters after the simulated night work were compared between the light conditions using paired t-tests. The ANOVA results indicated a significant interaction (light condition and3 day) (p = .006). Post hoc tests indicated that in the dim-light condition, the melatonin concentration was significantly lower on the second day than on the first day (p = .046); however, in the bright-light condition, there was no significant difference in the melatonin concentration between the days (p = .560). There was a significant difference in ΔDLMO between the conditions (p = .015): DLMO after sleeping was advanced by 11.1 ± 17.4 min under bright-light conditions but delayed for 7.2 ± 13.6 min after sleeping under dim-light conditions. No significant differences were found in any sleep parameter. Our study demonstrated that daytime sleeping under bright-light conditions after night work could not reduce late evening melatonin secretion until midnight or delay the phase of melatonin secretion without decreasing the quality of the daytime sleeping. Thus, these results suggested that, to enhance melatonin secretion and to maintain their conventional sleep–wake cycle, after night work, shift workers should sleep during the daytime under bright-light conditions rather than dim-light conditions.     

The effect of time of day and recovery type after a football game on muscle damage and performance in anaerobic tests on young soccer players

The purpose of this study was to investigate the effect of time of day and different modalities of recovery (active vs. passive recovery) after intermittent exercise in young soccer players. In randomized order, 16 boys participated in the study, divided into two groups: passive recovery (PRG, n?=?8) and active recovery (ARG, n?=?8). Both groups performed tests at 07:00 and 17:00 h. The results showed that performance in the Sargent jump test (SJT), 10-m sprint, and agility were higher in the evening (17:00 h), around the presumed peak of body temperature. SJT and agility performance decreased after the match. The better performance in SJT and agility were found in ARG rather than PRG (p?p?p?p?p?p?相似文献   

Daily rhythms in activity and mRNA abundance of enzymes involved in glucose and lipid metabolism in liver of rainbow trout,Oncorhynchus mykiss. Influence of light and food availability

ABSTRACT

We have investigated the magnitude of diurnal variation in back squat and bench press performance using the MuscleLab force velocity transducer. Thirty resistance-trained males (mean ± SD: age 21.7 ± 1.4 years; body mass 80.5 ± 4.5 kg; height 1.79 ± 0.06 m) underwent two sessions at different times of day: morning (M, 07:30 h) and evening (E, 17:30 h). Each session included a period when rectal temperature (T_rec) was measured at rest, a 5-min standardized 150 W warm-up on a cycle ergometer, then defined programme of bench press (at 20, 40 and 60 kg) and back squat (at 30, 50 and 70 kg) exercises. A linear encoder was attached to an Olympic bar used for the exercises and average force (AF), peak velocity (PV) and time-to-peak velocity (tPV) were measured (MuscleLab software; MuscleLab Technology, Langesund, Norway) during the concentric phase of the movements. Values for T_rec at rest were higher in the evening compared to morning values (0.48°C, P < 0.0005). Daily variations were apparent for both bench press and back squat performance for AF (1.9 and 2.5%), PV (8.3 and 12.7%) and tPV (?16.6 and ?9.8%; where a negative number indicates a decrease in the variable from morning to evening). There was a main effect for load where AF and tPV increased and PV decreased from the lightest load to the heaviest for both bench press and back squat (47.1 and 80.2%; 31.7 and 57.7%; ?42.1 and ?73.9%; P < 0.0005 where a negative number indicates a decrease in the variable with increasing load). An interaction was found only for tPV, such that the tPV occurs earlier in the evening than the morning at the highest loads (60 and 70 kg) for both bench press and back squat, respectively (mean difference of 0.32 and 0.62 s). In summary, diurnal variation in back squat and bench press was shown; and the tPV in complex multi-joint movements occurs earlier during the concentric phase of exercise when back squat or bench press is performed in the evening compared to the morning. This difference can be detected using a low cost, portable and widely available commercial instrument and enables translation of past laboratory/tightly controlled experimental research in to main-stream coaching practice.     

Association of the melatonin circadian rhythms with clock 3111T/C gene polymorphism in Caucasian and Asian menopausal women with insomnia

A comparative analysis of melatonin circadian rhythms in Caucasian (incoming population) and Asian (indigenous population) menopausal women with/without sleep disorders depending on the genotype of Clock 3111T/C gene polymorphism was realized.The melatonin level in the saliva was determined four times a day (6:00–7:00, 12:00–13:00, 18:00–19:00, 23:00–00:00 h). The Caucasian women—carriers of the TT-genotype with insomnia as compared to control group—had a higher morning melatonin level and a lower night melatonin level. The Asian women with TT-genotype and insomnia had a lower levels of melatonin as compared to control at daytime, evening and night. A significantly higher melatonin level in the early morning hours was detected in the Caucasian women—carriers of the TT-genotype with insomnia as compared to group womencarriers of the minor 3111C-allele. There were no statistically significant differences in the circadian rhythms of melatonin in the Asian women depending on the genotype of the Clock 3111T/C polymorphism. An assumption with respect to the protective role of the minor allele 3111C in the development of insomnia associated with the displacement of melatonin circadian rhythms in the representatives of the incoming population was made.