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1.
ABSTRACT

Purpose: The effect of breakfast omission on evening high-intensity exercise performance has not previously been studied. Methods: In a randomised and counterbalanced cross-over design, 10 competitive rowers (2 male, 8 female; mean?±?SD: age 21?±?2 y, height 176?±?7?cm, weight 76?±?12?kg, body fat 19.7?±?6.8%) completed two trials (individualised carbohydrate-rich breakfast (BT; 831?±?67?kcal eaten before 09:00) and no-breakfast (NBT; extended overnight fast until 12:00)). Following ad libitum afternoon food intake, participants completed a 2000-m time-trial on a rowing ergometer between 16:30 and 18:00. Appetite and energy intake were measured throughout the day, whilst power output, time, heart rate, blood lactate, blood glucose and RPE were assessed during the time trial. Results: Appetite ratings were higher throughout the morning in NBT compared with BT, but there were no differences in ratings in the afternoon. Energy intake at lunch was greater NBT compared with BT (1236?±?594 vs 836?±?303?kcal, p?<?.05), which partly compensated for breakfast omission, although overall energy intake tended to be lower in NBT compared with BT (1236?±?594 vs 1589?±?225?kcal, p?=?.08). The time taken to complete the 2000-m time trial was greater in NBT compared with BT (469.2?±?43.4 vs 465.7?±?43.3?s; p?<?.05). No differences in heart rate, blood glucose and blood lactate responses were apparent, but overall RPE was higher in NBT compared with BT (17.8?±?0.9 vs 16.7?±?0.7?au, p?<?.05). Conclusion: The omission of a carbohydrate-rich breakfast impaired evening performance during a 2000-m rowing time trial. This finding has implications for optimising evening high-intensity exercise performance.  相似文献   

2.
The aim of this study was to investigate the performance of an Olympic-Weightlifting session training at three times of the day on the performance related to biochemical responses. Nine weightlifters (21 ± 0.5 years) performed, in randomised order, on three Olympic-Weightlifting training (snatch, clean and jerk) sessions (08:00 a.m., 02:00 p. m., 06:00 p. m.). Blood samples were collected: before, 3 min and 48 h after each training session. Haematological parameters and markers of muscle injury were assessed. Resting oral temperature and rating of perceived exertion (RPE) were also assessed during each session. ANOVA showed that the performance was better (P < 0.001) at 02:00 p. m. with a less RPE (P < 0.01) compared to the morning and the evening sessions while there was higher (P < 0.05) oral temperature at 06:00 p. m. versus 08:00 a.m. and 02:00 p. m. Muscle damage changed immediately (without significant effect after 48 h) after the training sessions with lower values ??in the evening compared to the morning. In conclusion, the afternoon training is more effective than morning or evening sessions for weightlifters. Therefore, coaches and weightlifters should be advised to schedule their training session in the afternoon hour.  相似文献   

3.
Abstract

The aim of this study was to investigate the effects of sleep deprivation on autonomic and endocrine functions during the day and on exercise tolerance in the evening. Ten healthy young males completed two, 2-day control and sleep deprivation trials. For the control trial, participants were allowed normal sleep from 23:00 to 07:00 h. For the sleep deprivation trial, participants did not sleep for 34 h. Autonomic activity was measured from 19:00 h on day 1 to 16:00 h on day 2 by frequency-domain measures of heart rate variability. Endocrine function was examined by measuring adrenocorticotropic hormone and cortisol from venous blood samples collected on day 2 at 09:00, 13:00, and 17:00 h and immediately after an exercise tolerance testing. Autonomic regulation, particularly parasympathetic regulation estimated from the high-frequency component of heart rate variability analysis, was significantly higher in the sleep deprivation trial than in the control trial in the morning and afternoon of day 2. Plasma adrenocorticotropic hormone concentrations were significantly higher at 09:00 and 13:00 h of day 2 under sleep deprivation. Heart rate during exercise was significantly lower following sleep deprivation. Therefore, the effects of sleep deprivation on autonomic regulation depend on the time of the day.  相似文献   

4.
This study investigated the two different time-of-day effect on team-handball-related short-term maximal physical performances. At two different time-of-day, fifteen young female team handball players performed different physical tests: HandGrip (HG) test, Ball-Throwing Velocity (BTV) test, Modified Agility T-test (MAT) and Repeated Shuttle-Sprint and Jump Ability (RSSJA) test. Rating of perceived exertion (RPE) scale was determined following the termination of the last test. Measurements were performed at two separate testing sessions (i.e., in the morning (7:00–8:30 h) and in the early evening (17:00–18:30 h)) in a randomised and counter-balanced setting on non-consecutive days. The results showed that HG (P = 0.0013), BTV (P = 0.0027) and MAT (P < 0.001) performances were better in the evening compared with the morning. During RSSJA, both best and mean sprint times were shorter in the evening compared to the morning (P < 0.001). Moreover, during the latter test, mean jump performance was higher in the evening compared to the morning (P = 0.026). However, there was no morning–evening difference in the best jump performance during RSSJA. Likewise, jump performance decrement was not affected by the time-of-day of testing. On the other hand, RPE fluctuated, with morning nadirs and afternoon/early evening highest values. The findings suggest that in female team handball players, team-handball-related short-term maximal physical performances were better in the afternoon than in the morning.  相似文献   

5.
To determine the effect of circadian rhythm on neuromuscular responses and kinematics related to physical tennis performance, after a standardised warm-up, 13 highly competitive male tennis players were tested twice for serve velocity/accuracy (SVA), countermovement vertical jump (CMJ), isometric handgrip strength (IS), agility T-test (AGIL) and a 10-m sprint (10-m RUN). In a randomised, counter-balance order, tennis players underwent the test battery twice, either in the morning (i.e., AM; 9:00 h) and in the afternoon (i.e., PM; 16:30 h). Paired t-tests were used to analyse differences due to time-of-day in performance variables. Comparison of morning versus afternoon testing revealed that SVA (168.5 ± 6.5 vs. 175.2 ± 6.1 km · h?1; P = 0.003; effect size [ES] = 1.07), CMJ (32.2 ± 0.9 vs. 33.7 ± 1.1 cm; P = 0.018; ES = 1.46), AGIL (10.14 ± 0.1 vs. 9.91 ± 0.2 s; P = 0.007; ES = 1.23) and 10-m RUN time (1.74 ± 0.1 vs. 1.69 ± 0.1 s; P = 0.021; ES = 0.67) were significantly blunted during the morning testing. However, IS was not affected by time-of-day (P = 0.891). Thus, tennis performance may be reduced when competing in the morning in comparison to early evening. Therefore, coaches and tennis players should focus on schedule the SVA, power, speed and agility training sessions in the afternoon.  相似文献   

6.
In today’s leading football training centres, state-of-the-art performance diagnostic systems such as the “Footbonaut” allow controlled and standardized assessments of physical and mental components of agility, e.g. speed of action and ball control, that are considered to be decisive for talent identification and development. However, effects of induced physical and mental strain on performing football-specific practice patterns remain to be elucidated, particularly in youth players, and, thus, characterize the purpose of this study. 33 randomly assigned competitive football players (U14 to U16) performed a standardized Footbonaut practice pattern (i.e. 20 balls randomly drawn at 50?km/h each), prior to and immediately after either mentally demanding tasks (MDT; n?=?11; continuous Vienna Test System’s Stroop task and determination test), physically demanding tasks (PDT; n?=?11; consisted of 4?×?4?min of football-specific high-intensity intervals with 3?min of active recovery in between) or a control condition (CON; n?=?11). Continuous heart rates (HR) as well as self-perceptions of fatigue were assessed. Main findings revealed performances for speed of action (p?=?0.44; f?=?0.01) and ball control (p?=?0.15; f?=?0.03) that were not modulated in the face of induced physical and mental strain as indicated by increased HR following PDT (p?<?0.001; d?>?0.8), or in the face of increased self-perceptions of fatigue following PDT and MDT (both p?<?0.001; both d?>?0.8) compared to CON. This is in line with a suggested talent factor and previous reports on motivational trade-off aspects in youth players. However, the present study’s short-timed practice patterns make it difficult to reliably compare a measuring sensitivity to complex football-specific movement behavioural and technical proficiencies with respect to mental and physical strain of longer-lasting football games and, thus, need further investigation in favour of improving talent identification and development using the Footbonaut.  相似文献   

7.
ABSTRACT

The systematic review and meta-analysis evaluated the effect of aerobic, resistance and combined exercise on RMR (kCal·day-1) and performed a methodological assessment of indirect calorimetry protocols within the included studies. Subgroup analyses included energy/diet restriction and body composition changes. Randomized control trials (RCTs), quasi – RCTs and cohort trials featuring a physical activity intervention of any form and duration excluding single exercise bouts were included. Participant exclusions included medical conditions impacting upon RMR, the elderly (≥65 years of age) or pregnant, lactating or post-menopausal women. The review was registered in the International Prospective Register of Systematic Reviews (CRD 42,017,058,503). 1669 articles were identified; 22 were included in the qualitative analysis and 18 were meta-analysed. Exercise interventions (aerobic and resistance exercise combined) did not increase resting metabolic rate (mean difference (MD): 74.6 kCal·day-1[95% CI: ?13.01, 161.33], P = 0.10). While there was no effect of aerobic exercise on RMR (MD: 81.65 kCal·day-1[95% CI: ?57.81, 221.10], P = 0.25), resistance exercise increased RMR compared to controls (MD: 96.17 kCal·day-1[95% CI: 45.17, 147.16], P = 0.0002). This systematic review effectively synthesises the effect of exercise interventions on RMR in comparison to controls; despite heterogenous methodologies and high risk of bias within included studies.  相似文献   

8.
ABSTRACT

The optimal scheduling of Nordic Hamstring exercises (NHEs) relative to football training sessions is unknown. We examined the acute neuromuscular and performance responses to NHE undertaken either before (BT) or after (AT) simulated football training. Twelve amateur players performed six sets of five repetitions of the NHE either before or after 60 min of standardised football-specific exercise (SAFT60). Surface electromyography signals (EMG) of the hamstring muscles were recorded during both the NHE, and maximum eccentric actions of the knee flexors (0.52 rad · s–1) performed before and after the NHE programme, and at 15 min intervals during SAFT60. Ten-metre sprint times were recorded on three occasions during each 15 min SAFT60 segment. Greater eccentric hamstring fatigue following the NHE programme was observed in BT versus AT (19.8 %; very likely small effect), which was particularly apparent in the latter range of knee flexion (0–15°; 39.6%; likely moderate effect), and synonymous with hamstring EMG declines (likely small–likely moderate effects). Performing NHE BT attenuated sprint performance declines (2.0–3.2%; likely small effects), but decreased eccentric hamstring peak torque (–14.1 to –18.9%; likely small effects) during football-specific exercise. Performing NHE prior to football training reduces eccentric hamstring strength and may exacerbate hamstring injury risk.  相似文献   

9.
Abstract

In this study, we examined the effects of time-of-day-specific strength training on maximum strength and electromyography (EMG) of the knee extensors in men. After a 10-week preparatory training period (training times 17:00–19:00 h), 27 participants were randomized into a morning (07:00–09:00 h, n = 14) and an evening group (17:00–19.00 h, n = 13). Both groups then underwent 10 weeks of time-of-day-specific training. A matched control group (n = 7) completed all testing but did not train. Unilateral isometric knee extension peak torque (MVC) and one-repetition maximum half-squat were assessed before and after the preparatory training and after the time-of-day-specific training at times that were not training-specific (between 09:00 and 16:00 h). During training-specific hours, peak torque and EMG during MVC and submaximum isometric contraction at 40% MVC were assessed before and after the time-of-day-specific training. The main finding was that a significant diurnal difference (P < 0.01) in peak torque between the 07:00 and 17:00 h tests decreased after time-of-day-specific training in the morning group but not in the evening or control groups. However, the extent of this time-of-day-specific adaptation varied between individuals. Electromyography during MVC did not show any time-of-day-specific adaptation, suggesting that peripheral rather than neural adaptations are the main source of temporal specificity in strength training.  相似文献   

10.
Abstract

Although exercise training is unable to improve obesity-associated decreases in left ventricular (LV) diastolic function, as assessed using chamber function measurements, the effects on LV diastolic myocardial function, as assessed using tissue Doppler imaging (TDI), are uncertain. In 32 overweight (n = 11) or obese (n = 21), sedentary or recreationally active men and women (30–57 years), we assessed the effects of 6 weeks of exercise training either preceded (n = 16) or followed (n = 16) by a 6-week control period on TDI indices of LV diastolic function (e', e'/a' and E/e') (echocardiography). Diastolic function at baseline was comparable to that noted in overweight and obese participants from a community sample (n = 245), and 56% (n = 18) had e' values below the lower 95% CI of a lean and healthy cohort (n = 60) of the community sample. Exercise training increased peak oxygen consumption (27.4 ± 4.9 to 29.4 ± 5.8 mL · kg–1 · min–1, P = 0.0001), but had no effect on body mass index (P = 0.99). No changes in TDI indices of diastolic function were observed after exercise training in all the participants (e': P = 0.74, a': P = 0.98, e'/a': P = 0.85, E/e': P = 0.26), participants with abnormal e' values (n = 18)(e': P = 0.99, a': P = 0.96, e'/a': P = 0.91, E/e': P = 0.97) or obese participants (n = 21)(e': P = 0.67, a': P = 1.00, e'/a': P = 0.78, E/e': P = 0.11). In conclusion, exercise training, despite increasing cardiorespiratory fitness, is unable to improve obesity-associated decreases in LV diastolic myocardial function.  相似文献   

11.
The jump throw is one of the most applied techniques in handball. Therefore, analyzing its underlying performance factors is important since they may provide a basis to adjust training interventions. Currently, the coach decides what needs to be improved in order to enhance the overall performance of an athlete. The aim of this study is to break down the performance factors in jump throws and to assign athletes to subgroups. This classification should allow athletes to benefit from the resulting group-specific training contents and may support a coach in deciding about the next steps in his training program. A total of 113 male handball players (age 15 ± 0.38 years, height 184.07 ± 7.1?cm, weight 74.83 ± 9.31?kg) participated in this study. From each athlete the standing reach height (SRH), the jumping reach height achieved with a countermovement jump (JRH), the maximal ball height achieved with a handball-specific single-legged jump and straight arm (BHJ), and the ball release height achieved in a jump throw (BHT) were measured. Performance factors were derived as differences between these measurements (JRH ? SRH = UJA for unspecific jump ability, BHJ ? JRH = SJT for specific jump technique, BHT ? BHJ = STT for specific throwing technique). A hierarchical cluster analysis was used to find groups of athletes based on the derived and scaled difference measures (UJA, SJT, STT). The dendrogram shows a clear distinction of four groups of athletes. Average values within each cluster reveal (A) one group with high UJA values, (B) one with low UJA values, (C) one with high SJT but low STT, and (D) one with low SJT but high STT. These results may be interpreted with respect to consequences for training because group (B) seems to benefit most from a general strength training while the properties of group (A), (C), and (D) recommend a focus on technical aspects of performance.  相似文献   

12.
Professional competency of sport and exercise coaches has been conceptualised differently depending on the theoretical and methodical approach taken. To date, no model of professional coaching competency has been agreed upon. The aim of this study was to develop a competency model for sport coaches drawing on well-known competency models developed in the context of teacher education and to empirically assess parts of the model. We developed an initial pool of 295 multiple choice items and administered them to a sample of 531 youths (mean age: 16.2 years) directly after they had completed the German Football Association’s (Deutscher Fußball-Bund) “Junior Coach in Schule und Verein” (Junior Coach for Schools and Clubs) training programme. Results of analyses of one-, two-, five-, and six-dimensional models by means of Rasch scaling indicate that the data are best represented by either a two- or a five-dimensional model depending on the fit criteria chosen. While content knowledge and pedagogical content knowledge are presented in the two-dimensional model, the five-dimensional model allows discrimination among football-specific content knowledge, basic content knowledge of training science, basic content knowledge of first aid and pedagogical content knowledge of planning training sessions and instructional/methodological pedagogical knowledge. Further investigation should be made into the suitability of competency models developed in the context of teacher evaluation for modelling the competency of sport coaches and into the extent to which such models can be extrapolated to various sports.  相似文献   

13.
Li TL  Gleeson M 《Journal of sports sciences》2004,22(11-12):1015-1024
The purpose of this study was to establish the effect of exercise at different times of day on saliva flow rate, immunoglobulin A (sIgA) concentration and secretion rate, and alpha-amylase activity, and to establish how these parameters change following a second exercise bout performed on the same day. In a counterbalanced design, eight male volunteers participated in three experimental trials separated by at least 4 days. On the trial with afternoon exercise only, the participants cycled for 2 h at 60% VO2max starting at 14:00 h. On the other two trials, participants performed either two bouts of exercise at 60% VO2max for 2 h (the first started at 09:00 h and the second started at 14:00 h) or a separate resting trial. Unstimulated saliva samples were obtained 10 min before exercise, after 58 - 60 min and during the last 2 min of exercise, and at 1 h and 2 h after exercise. Venous blood samples were taken 5 min before exercise and immediately after exercise for both bouts. Participants remained fasted between 23:00 h on the day before the trials and 18:00 h on the day of the trial. Circadian variations were found in sIgA concentration, which decreased with time from its highest value in the early morning to its lowest value in the evening, and salivary alpha-amylase secretion rate, which increased from its lowest value in the morning to its highest value in the late afternoon. Cycling at 60% VO2max for 2 h significantly decreased saliva flow rate, increased sIgA concentration and alpha-amylase activity, but did not influence sIgA secretion rate. Performing prolonged cycling at different times of day did not differentially affect the salivary and plasma hormonal responses in the short term. Performance of a second prolonged exercise bout elicited a greater plasma stress hormone response but did not appear to compromise oral immunity acutely. These findings also suggest that, in terms of saliva secretion, sIgA and alpha-amylase responses, a 3 h rest is enough to recover from previous strenuous exercise. During such exercise, sympathetic stimulation appears to be strong enough to inhibit saliva flow rate; however, it appears that it does not increase sIgA output via transcytosis.  相似文献   

14.
In the context of strength training in rehabilitation, visual movement control can be helpful to ensure correct movements. However, there are only a few studies that deal with the effectiveness of feedback during resistance exercises. To investigate the effect of feedback during guided exercise, 18 young adults (28.8?±?5.5 years) and 12 senior citizens (67.9?±?4.1 years) were tested. Subjects performed shoulder press exercises (3 sets, 15 repetitions) with and without visual movement control in a randomized order. On day 1, the subjects trained without load, and on day 2 they trained at 50% of their single repetition maximum. Joint articulation at the elbow was recorded using elbow extension and flexion. Autocorrelation was used to determine the reproducibility of movements. Subjects achieved better reproducibility of the movement with feedback than without (χ2?=?19.73; p?<?0.001). There was no effect of the load on motion accuracy (p?>?0.05), but the age group showed a significant effect (χ2?=?6.00; p?=?0.014). The younger group shows a higher degree of movement accuracy. In summary, visual movement control is useful in guided exercises to control movement execution. In clinical setting, this may be a way to control the motion performance of guided strength exercises and to ensure purposeful muscle work. Further studies should clarify the effect of visual feedback on the movement quality in unguided strength exercises.  相似文献   

15.
Foam rolling and eccentric exercise interventions have been demonstrated to improve range of motion (ROM). However, these two modalities have not been directly compared. Twenty-three academy soccer players (age: 18 ± 1; height: 1.74 ± 0.08 m; body mass: 69.3 ± 7.5 kg) were randomly allocated to either a foam rolling (FR) or eccentric exercise intervention designed to improve dorsiflexion ROM. Participants performed the intervention daily for a duration of four weeks. Measurements of dorsiflexion ROM, isometric plantar flexion torque and drop jump reactive strength index were taken at baseline (pre-intervention) and at three subsequent time-points (30-min post, 24-hours post and 4-weeks post). A significant time x group interaction effect was observed for dorsiflexion (P = 0.036), but not for torque or reactive strength index. For dorsiflexion, there was a significant increase in both acute (30-min; P < 0.001) and chronic (4-week; P < 0.001) ROM for the eccentric group, whilst FR exhibited only an acute improvement (P < 0.001). Eccentric training would appear a more efficacious modality than foam rolling for improving dorsiflexion ROM in elite academy soccer players.  相似文献   

16.
Purpose: Acute muscle damage after exercise triggers subsequent regeneration, leading to hypertrophy and increased strength after repeated exercise. It has been debated whether acute exercise-induced muscle damage is altered under various premenopausal estrogen conditions. Acute contraction-induced muscle damage was compared during exogenous (oral contraceptive, OC), endogenous (luteal phase, HI), or low (menses, LO) estrogen in healthy young women aged 21 to 30 years old. Methods: Women (OC, n = 9; HI, n = 9; LO, n = 8; total N = 26) performed 1 neuromuscular electrical stimulation (NMES) bout. Soreness, measured via visual analog scale and the Likert Scale of Muscle Soreness for Lower Limb (LSMSLL), quadriceps strength, and plasma myoglobin (Mb), interleukin (IL)-6, IL-8, and granulocyte-colony stimulating factor were measured before and after NMES. Results: NMES performance was similar across groups. Meaningful within-group increases in Mb (effect size [ES] = 1.12) and IL-8 (ES = 0.38) occurred in LO; ES for HI and OC were trivial. ES of the between-group difference in change was moderate for Mb (LO vs. HI = 1.15) and IL-8 (LO vs. HI = 0.86; LO vs. OC = 0.73). 17-β estradiol correlated moderately and negatively with Mb relative change (r = –.52, p < .05). LO had ~5% greater strength loss than OC and HI. The mean change score for the LSMSLL 2 days post-NMES was clinically greater in LO than OC or HI. Conclusions: Acute NMES-induced indicators of muscle fiber damage and qualitative muscle soreness may be attenuated during the luteal phase or active OC pill consumption compared with the menstrual phase.  相似文献   

17.
The effect of time of day on ratings of perceived exertion (RPE) at various intensities of cycling exercise, both below and above the ventilatory threshold, was studied in 32 subjects, 18 to 35 years of age. The ventilatory threshold occurred at the same (p greater than .05) mean (+/- SD) work rate in the morning (110.6 +/- 27.0 watts) and in the afternoon (111.9 +/- 23.9 watts) and was perceived as equally strenuous (p greater than .05) in the morning (RPE = 13.8 +/- 2.4) and in the afternoon (RPE = 13.6 +/- 2.8). At intensities below the ventilatory threshold, RPE was the same (p greater than .05) in the morning and in the afternoon; above the ventilatory threshold, RPE was lower (p less than .05) in the morning. We conclude that, during incremental submaximal cycling exercise above the ventilatory threshold, a particular work rate is perceived as less strenuous in the morning than in the afternoon. About 20% of this difference in RPE is explained by lower ventilatory demands in the morning.  相似文献   

18.
The effectiveness of a nap as a recovery strategy for endurance exercise is unknown and therefore the present study investigated the effect of napping on endurance exercise performance. Eleven trained male runners completed this randomised crossover study. On two occasions, runners completed treadmill running for 30?min at 75% ?O2max in the morning, returning that evening to run for 20?min at 60% ?O2max, and then to exhaustion at 90% ?O2max. On one trial, runners had an afternoon nap approximately 90?min before the evening exercise (NAP) whilst on the other, runners did not (CON). All runners napped (20?±?10?min), but time to exhaustion (TTE) was not improved in all runners (NAP 596?±?148?s vs. CON 589?±?216?s, P?=?.83). Runners that improved TTE after the nap slept less at night than those that did not improve TTE (night-time sleep 6.4?±?0.7?h vs. 7.5?±?0.4?h, P?r2 ? =??0.76, P?=?.001). In runners that improved TTE, ratings of perceived exertion (RPE) were lower during the TTE on NAP than CON compared to runners that did not improve (?0.4?±?0.6 vs. 0?±?0, P?=?.05). Reduced exercising sense of effort (RPE) may account for the improved TTE after the nap. In conclusion, a short afternoon nap improves endurance performance in runners that obtain less than 7?h night-time sleep.  相似文献   

19.
The aim of this study was to assess the effect of time of day on physiological responses to running at the speed at the lactate threshold. After determination of the lactate threshold, using a standard incremental protocol, nine male runners (age 26.3 - 5.7 years, height 1.77 - 0.07 m, mass 73.1 - 6.5 kg, lactate threshold speed 13.6 - 1.6 km· h -1 ; mean - s ) completed a standardized 30 min run at lactate threshold speed, twice within 24 h (07:00- 09:00 h and 18:00-21:00 h). Core body temperature, heart rate, minute ventilation, oxygen uptake, carbon dioxide expired, respiratory exchange ratio and capillary blood lactate were measured at rest, after a warm-up and at 10, 20 and 30 min during the run. In addition, the rating of perceived exertion was reported every 10 min during the run. Significant diurnal variation was observed only for body temperature (36.9 - 0.9°C vs 37.3 - 0.3°C) and respiratory exchange ratio at rest (0.86 - 0.01 vs 0.89 - 0.07) ( P ? 0.05). Diurnal variation persisted for body temperature throughout the warm-up (37.1 - 0.2°C vs 37.5 - 0.3°C) and during exercise (36.2 - 0.6°C vs 38.6 - 0.4°C), but only during the warm-up for the respiratory exchange ratio (0.85 - 0.05 vs 0.87 - 0.02) ( P ? 0.05). The rating of perceived exertion was significantly elevated during the morning trial (12.7 - 0.9 vs 11.9 - 1.2) ( P ? 0.05). These findings suggest that, despite the diurnal variation in body temperature, other physiological responses to running at lactate threshold speed are largely unaffected. However, a longer warm-up may be required in morning trials because of a slower increase in body temperature, which could have an impact on ventilation responses and ratings of perceived exertion.  相似文献   

20.
The aim of this investigation is to assess the effectiveness of a 6-week balance training (BT) protocol, integrated in regular training sessions, on postural sway of young female volleyball players (n = 26, age 13.0 ± 0.2 years) divided into two groups (intervention and control; 13 per group). Trials were performed for bipedal and unipedal stance conditions before and after the BT protocol, using a pressure platform to collect center-of-pressure (COP) time series that were processed to calculate sway area, COP path length, and maximum displacement range in anteroposterior and mediolateral directions. The intervention group exhibited smaller sway areas in eyes closed conditions (intervention = 42.76 mm2, control = 67.60 mm2; p < 0.05) and Romberg quotients (intervention = 1.11 mm, control = 1.82 mm) in bipedal stance, while all the other parameters were unaffected. BT also reduced sway area (intervention = 122.70 mm2, control = 187.18 mm2) and anteroposterior COP displacements (intervention = 20.18 mm, control = 22.38 mm) of the non-dominant limb for single-leg stance. No significant change was found for the dominant limb. Although it is possible to hypothesize a beneficial effect of BT on young athletes, further investigations are required to clarify its actual effect on balance performance with respect to normal volleyball training.  相似文献   

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