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1.
ABSTRACT

The effects of acute ingestion of nitrate on short-duration repeated sprint performance (RSP) are unclear. This study investigated the effect of acute ingestion of beetroot juice on a test of RSP in team sport athletes. Sixteen male team sport athletes undertook four trials using a 40 m maximum shuttle run test (MST), which incorporates 10 × 40 m shuttle sprints with 30 s between the start of each sprint. Two familiarisation trials, followed by nitrate-rich beetroot juice (BR; ~6 mmol nitrate) and nitrate-depleted beetroot juice (PLA; ~0.0034 mmol nitrate) trials were completed in a randomised, double-blind manner. Ingestion of beetroot juice 3 h prior to exercise elevated plasma nitrate concentrations ~6-fold in BR (BR, 413 ± 56 μM; PLA, 69 ± 30 μM; P < 0.001). RSP, assessed by sprint performance decrement (Sdec; %), did not differ (P = 0.337) between BR (5.31 ± 2.49%) and PLA (5.71 ± 2.61%). There was no difference between trials for total sprint time (P = 0.806), fastest sprint (P = 0.341), slowest sprint (P = 0.787), or post-exercise blood lactate concentration (BR, 11.8 ± 2.5 mM; PLA, 12.2 ± 2.3 mM; P = 0.109). Therefore, acute ingestion of beetroot juice did not improve a test of short-duration RSP in team sport athletes.  相似文献   

2.
The insulin response following carbohydrate ingestion enhances creatine transport into muscle. Cinnamon extract is promoted to have insulin-like effects, therefore this study examined if creatine co-ingestion with carbohydrates or cinnamon extract improved anaerobic capacity, muscular strength, and muscular endurance. Active young males (n?=?25; 23.7?±?2.5?y) were stratified into 3 groups: (1) creatine only (CRE); (2) creatine+ 70?g carbohydrate (CHO); or (3) creatine+ 500?mg cinnamon extract (CIN), based on anaerobic capacity (peak power·kg?1) and muscular strength at baseline. Three weeks of supplementation consisted of a 5?d loading phase (20?g/d) and a 16?d maintenance phase (5?g/d). Pre- and post-supplementation measures included a 30-s Wingate and a 30-s maximal running test (on a self-propelled treadmill) for anaerobic capacity. Muscular strength was measured as the one-repetition maximum 1-RM for chest, back, quadriceps, hamstrings, and leg press. Additional sets of the number of repetitions performed at 60% 1-RM until fatigue measured muscular endurance. All three groups significantly improved Wingate relative peak power (CRE: 15.4% P?=?.004; CHO: 14.6% P?=?.004; CIN: 15.7%, P?=?.003), and muscular strength for chest (CRE: 6.6% P?P?P?P?P?P?P?=?.013; CHO: 10.0% P?=?.007; CIN: 17.3% P?P?=?.021) and CIN (15.5%, P?相似文献   

3.
Scientific information about the effects of caffeine intake on combat sport performance is scarce and controversial. The aim of this study was to investigate the effectiveness of caffeine to improve Brazilian Jiu-jitsu (BJJ)-specific muscular performance. Fourteen male and elite BJJ athletes (29.2?±?3.3?years; 71.3?±?9.1?kg) participated in a randomized double-blind, placebo-controlled and crossover experiment. In two different sessions, BJJ athletes ingested 3?mg?kg?1 of caffeine or a placebo. After 60?min, they performed a handgrip maximal force test, a countermovement jump, a maximal static lift test and bench-press tests consisting of one-repetition maximum, power-load, and repetitions to failure. In comparison to the placebo, the ingestion of the caffeine increased: hand grip force in both hands (50.9?±?2.9 vs. 53.3?±?3.1?kg; respectively p?p?=?.02), and time recorded in the maximal static lift test (54.4?±?13.4 vs. 59.2?±?11.9?s; p?p?=?.02), maximal power obtained during the power-load test (750.5?±?154.7 vs. 826.9?±?163.7?W; p?p?=?.04). In conclusion, the pre-exercise ingestion of 3?mg?kg?1 of caffeine increased dynamic and isometric muscular force, power, and endurance strength in elite BJJ athletes. Thus, caffeine might be an effective ergogenic aid to improve physical performance in BJJ.  相似文献   

4.
Aim: Recent meta-analyses of the literature confirmed the association between the RR+RX genotype of the ACTN3 R577X polymorphism and elite sprint/power athletic status in Europeans but not in Asians and Africans, while the association between the R577X genotype and elite endurance athlete status is less convincing. The aim of the present study was to investigate the association between the ACTN3 R577X genotype and elite athlete status in a large Asian (Japanese) cohort of track and field athletes. Methods: One-thousand fifty-seven Japanese track and field athletes (627 sprint/power athletes and 430 endurance athletes) and 810 Japanese controls were genotyped for the ACTN3 R577X polymorphism (rs1815739) by using the TaqMan® SNP Genotyping Assay. Results: Elite sprint/power athletes had a higher frequency of the RR+RX genotype than the controls (OR: 1.59, 95% CI: 1.16–2.18; P?=?.003). A significant linear correlation was found between the RR?+?RX genotype and athlete status (i.e. regional?P?=?.001 for trend) and long-distance runners (regional: 65%, national: 72%, international: 82%; P?=?.030 for trend). Conclusions: The data obtained for this large Asian (Japanese) cohort of track and field athletes served to confirm the association between the RR?+?RX genotype of the ACTN3 R577X polymorphism and elite sprint/power athlete status and also the association between the ACTN3 RR?+?RX genotype and long-distance running athletic status.  相似文献   

5.
The effects of pomegranate extract (PE) supplementation were evaluated on high-intensity exercise performance, blood flow, vessel diameter, oxygen saturation (SPO2), heart rate (HR), and blood pressure (BP). In a randomized, crossover design, nineteen recreationally resistance-trained participants were randomly assigned to PE (1000?mg) or placebo (PL), which were consumed 30?min prior to a repeated sprint ability (RSA) test and repetitions to fatigue (RTF) on bench and leg press. The RSA consisted of ten six-second sprints on a friction-loaded cycle ergometer with 30?s recovery. Brachial artery blood flow and vessel diameter were assessed by ultrasound. Blood flow, vessel diameter, SPO2, HR, and BP were assessed at baseline, 30?min post ingestion, immediately post exercise (IPost), and 30?min post exercise (30minPost). With PE, blood flow significantly increased IPost RSA (mean difference?=?18.49?mL?min?1; P?<?.05), and IPost and 30minPost RTF (P?<?.05) according to confidence intervals (CI). Vessel diameter increased significantly 30minPost RSA according to CI and resulted in a significant interaction IPost and 30minPost RTF (P?<?.05). With PE, according to CI, average and peak power output increased significantly in sprint 5 of the RSA (P?<?.05). There was no significant difference between PE and PL for bench (P?=?.25) or leg press (P?=?.15) repetitions. Acute PE supplementation enhanced vessel diameter and blood flow, suggesting possible exercise performance enhancement from increased delivery of substrates and oxygen. The acute timing and capsule form of PE may be advantageous to athletic populations due to ergogenic effects, taste, and convenience.  相似文献   

6.
Purpose: The goal of this study was to determine the effects of repeated-sprint training in hypoxia induced by voluntary hypoventilation at low lung volume (VHL) on running repeated-sprint ability (RSA) in team-sport players.

Methods: Twenty-one highly trained rugby players performed, over a 4-week period, seven sessions of repeated 40-m sprints either with VHL (RSH-VHL, n?=?11) or with normal breathing (RSN, n?=?10). Before (Pre-) and after training (Post-), performance was assessed with an RSA test (40-m all-out sprints with a departure every 30?s) until task failure (85% of the reference velocity assessed in an isolated sprint).

Results: The number of sprints completed during the RSA test was significantly increased after the training period in RSH-VHL (9.1?±?2.8 vs. 14.9?±?5.3; +64%; p?p?=?.74). Maximal velocity was not different between Pre- and Post- in both groups whereas the mean velocity decreased in RSN and remained unchanged in RSH-VHL. The mean SpO2 recorded over an entire training session was lower in RSH-VHL than in RSN (90.1?±?1.4 vs. 95.5?±?0.5%, p?Conclusion: RSH-VHL appears to be an effective strategy to produce a hypoxic stress and to improve running RSA in team-sport players.  相似文献   

7.
So far, the relationship between wind and athletics performance has been studied mainly for 100 m sprint, based on simulation of biomechanical models, requiring several assumptions. In this study, this relationship is quantified empirically for all five horizontal jump and sprint events where wind is measured, with freely available competition results. After systematic scraping several elite and sub-elite results sites, the obtained results (n?=?150,169) were filtered and matched to athletes. A quadratic mixed effects model with athlete and season as random effects was applied to express the influence of wind velocity on performance in each event. Whether this effect differs with performance level was investigated by applying the model on subgroups based on performance level. In the fitted quadratic model, the linear coefficients were significant (p?p?p?=?.138). A 2.0?m?s?1 tail wind provides an average advantage of 0.125, 0.140 and 0.146?s for the 100, 200 and 100/110 m hurdles, respectively, and an advantage of 0.058 and 0.102 m for long jump and triple jump, respectively. Performance level had a significant effect on the wind influence only for 100 m (p??1 tail wind than elite athletes (～10?s). Practical formulas are presented for each event. These can easily be used correct results for wind speed, allowing better talent scouting and championship selection. This study demonstrates the efficacy of answering scientific questions empirically, through freely available data.  相似文献   

8.
Citrulline-malate (CM) is a precursor to nitric-oxide (NO) in the NO synthase (NOS) pathway and is suggested to increase exercise performance in younger individuals. With age, NO production decreases and augmented NO production may provide beneficial effects on sports performance among masters athletes (MAs). Purpose: To examine the effects of acute CM supplementation on grip strength, vertical power, and anaerobic cycling performance in female, MA tennis players. Methods: Seventeen female MA (51?±?9 years) completed two double-blind, randomized trials consuming CM (12?g dextrose?+?8?g CM) and placebo (PLA) (12?g dextrose). One hour after consumption, subjects completed grip strength, vertical power, and Wingate anaerobic cycling assessments in respective order. Maximal and average grip strength, peak and average vertical power, anaerobic capacity, peak power, explosive power, and ability to sustain anaerobic power were calculated from the tests. Results: When consuming CM, participants exhibited greater maximal (p?=?.042) and average (p?=?.045) grip strength compared to PLA. No differences existed between trials for peak (p?=?.51) or average (p?=?.51) vertical power. For the Wingate, peak power (p?p?p?Conclusions: These data suggest that consuming CM before competition has the potential to improve tennis match-play performance in masters tennis athletes. However, this study utilized a controlled laboratory environment and research evaluating direct application to on-court performance is warranted.  相似文献   

9.
To ensure that elite adolescent athletes meet their unique training, growth and maturation demands, it is imperative to have access to valid measures of energy intake. Contemporary methods demand close attention-to-detail, meaning that athletes often do not fully adhere to real-time protocols. This study represents the first investigation of a real-time dietary assessment designed using a comprehensive behaviour change framework (COM-B). In a crossover design, 12 elite adolescent male rugby players recorded their energy intake via an estimated food diary (est-FD) and photography-based mobile assessment (‘Snap-n-Send’), combined with a 24-h dietary recall interview. Two 4-day assessment periods were divided into three separate recording environments: 96?h free-living and researcher-observed; 72?h free-living and 10?h researcher-observed. Assessment periods were one month apart. All foods and beverages were provided and weighed by the research team to quantify actual intakes. ‘Snap-n-Send’ reported a small mean bias for under-reporting across 96?h (?0.75?MJ?day?1; 95% confidence interval [CI] for bias?=??5.7% to ?2.2%, p?<?.001), 72?h (?0.76?MJ?day?1; 95% CI for bias?=??5.6% to ?2.1%, p?=?.004) and 10?h (?0.72?MJ?day?1; 95% CI for bias?=??8.1% to ?0.1%; p?=?.067) environments. The est-FD reported a moderate mean bias for under-reporting across 96?h (?2.89?MJ?day?1; 95% CI for bias?=??17.9% to ?10.2%; p?<?.001), 72?h (?2.88?MJ?day?1; 95% CI for bias?=??17.9% to ?10.1%; p?<?.001) and 10?h (?2.52?MJ?day?1;?26.1% to ?5.3%; p?=?.023) environments. Results evidence the ability of ‘Snap-n-Send’ to accurately assess the diet of elite adolescent athletes, signalling the exciting promise of this comprehensive and theoretical behavioural approach within valid dietary assessment.  相似文献   

10.
Attenuated performance during intense exercise with limited endogenous carbohydrate (CHO) is well documented. Therefore, this study examined whether caffeine (CAF) mouth rinsing would augment performance during repeated sprint cycling in participants with reduced endogenous CHO. Eight recreationally active males (aged 23?±?2?yr, body mass 84?±?4?kg, stature 178?±?7?cm) participated in this randomized, single-blind, repeated-measures crossover investigation. Following familiarization, participants attended two separate evening glycogen depletion sessions. The following morning, participants completed five, 6?s sprints on a cycle ergometer (separated by 24?s active recovery), with mouth rinsing either (1) a placebo solution or (2) a 2% CAF solution. During a fifth visit, participants completed the sprints without prior glycogen depletion. Repeated-measures ANOVA identified significant main effect of condition (CAF, placebo, and control [P?P?P?P?P?P?相似文献   

11.
Abstract

It is a common requirement in tournament scenarios for athletes to compete multiple times in a relatively short time period, with insufficient recovery time not allowing full restoration of physical performance. This study aimed to develop a greater understanding of the physiological stress experienced by athletes in a tournament scenario, and how a commonly used recovery strategy, cold water immersion (CWI), might influence these markers. Twenty-one trained male games players (age 19?±?2; body mass 78.0?±?8.8?kg) were randomised into a CWI group (n?=?11) or a control group (n?=?10). To simulate a tournament, participants completed the Loughborough Intermittent Shuttle Test (LIST) on three occasions in five days. Recovery was assessed at specific time points using markers of sprint performance, muscle function, muscle soreness and biochemical markers of damage (creatine kinase, CK), inflammation (IL-6 and C-Reactive Protein) and oxidative stress (lipid hydroperoxides and activity of 6 lipid-soluble antioxidants). The simulated tournament was associated with perturbations in some, but not all, markers of physiological stress and recovery. Cold water immersion was associated with improved recovery of sprint speed 24?h after the final LIST (ES?=?0.83?±?0.59; p?=?.034) and attenuated the efflux of CK pre- and post-LIST 3 (p?<?.01). The tournament scenario resulted in an escalation of physiological stress that, in the main, cold water immersion was ineffective at managing. These data suggest that CWI is not harmful, and provides limited benefits in attenuating the deleterious effects experienced during tournament scenarios.  相似文献   

12.
Caffeine and coffee are widely used among active individuals to enhance performance. The purpose of the current study was to compare the effects of acute coffee (COF) and caffeine anhydrous (CAF) intake on strength and sprint performance. Fifty-four resistance-trained males completed strength testing, consisting of one-rep max (1RM) and repetitions to fatigue (RTF) at 80% of 1RM for leg press (LP) and bench press (BP). Participants then completed five, 10-second cycle ergometer sprints separated by one minute of rest. Peak power (PP) and total work (TW) were recorded for each sprint. At least 48 hours later, participants returned and ingested a beverage containing CAF (300?mg flat dose; yielding 3–5?mg/kg bodyweight), COF (8.9?g; 303?mg caffeine), or placebo (PLA; 3.8?g non-caloric flavouring) 30 minutes before testing. LP 1RM was improved more by COF than CAF (p?=?.04), but not PLA (p?=?.99). Significant interactions were not observed for BP 1RM, BP RTF, or LP RTF (p?>?.05). There were no sprint?×?treatment interactions for PP or TW (p?>?.05). 95% confidence intervals revealed a significant improvement in sprint 1 TW for CAF, but not COF or PLA. For PLA, significant reductions were observed in sprint 4 PP, sprint 2 TW, sprint 4 TW, and average TW; significant reductions were not observed with CAF or COF. Neither COF nor CAF improved strength outcomes more than PLA, while both groups attenuated sprint power reductions to a similar degree. Coffee and caffeine anhydrous may be considered suitable pre-exercise caffeine sources for high-intensity exercise.  相似文献   

13.
Abstract

This study investigated the effects of upper-body repeated-sprint training in hypoxia vs. in normoxia on world-level male rugby union players’ repeated-sprint ability (RSA) during an international competition period. Thirty-six players belonging to an international rugby union male national team performed over a 2-week period four sessions of double poling repeated-sprints (consisting of 3 × eight 10-s sprints with 20-s passive recovery) either in normobaric hypoxia (RSH, simulated altitude 3000 m, n?=?18) or in normoxia (RSN, 300 m; n?=?18). At pre- and post-training intervention, RSA was evaluated using a double-poling repeated-sprint test (6 × 10-s maximal sprint with 20-s passive recovery) performed in normoxia. Significant interaction effects (P?<?0.05) between condition and time were found for RSA-related parameters. Compared to Pre-, peak power significantly improved at post- in RSH (423?±?52 vs. 465?±?69 W, P?=?0.002, η²=0.12) but not in RSN (395?±?65 vs. 397?±?57 W). Averaged mean power was also significantly enhanced from pre- to post-intervention in RSH (351?±?41 vs. 388?±?53 W, P?<?0.001, η²=0.15), while it remained unchanged in RSN (327?±?49 vs. 327?±?43 W). No significant change in sprint decrement (P?=?0.151, η²?=?0.02) was observed in RSH (?17?±?2% vs. ?16?±?3%) nor RSN (?17?±?2% vs. ?18?±?4%). This study showed that only four upper-body RSH sessions were beneficial in enhancing repeated power production in international rugby union players. Although the improvement from RSA to game behaviour remains unclear, this finding appears of practical relevance since only a short preparation window is available prior to international games.  相似文献   

14.
This investigation examined the effect of beetroot juice (BR) supplementation, a source of dietary nitrate (NO3?), on cycling time-trial (TT) performance and thermoregulation in the heat. In a double-blind, repeated-measures design, 12 male cyclists (age 26.6 ± 4.4 years, VO2peak 65.8 ± 5.5 mL.kg?1.min?1) completed four cycling TTs (14 kJ.kg?1) in hot (35°C, 48% relative humidity) and euthermic (21°C, 52%) conditions, following 3 days supplementation with BR (6.5 mmol NO3? for 2 days and 13 mmol NO3? on the final day), or NO3–depleted placebo (PLA). Salivary NO3? and nitrite, core (Tc) and mean skin temperature (Tsk) were measured. Salivary NO3? and nitrite increased significantly post-BR supplementation (p < 0.001). Average TT completion time (mm:ss) in hot conditions was 56:50 ± 05:08 with BR, compared with 58:30 ± 04:48 with PLA (p = 0.178). In euthermic conditions, average completion time was 53:09 ± 04:35 with BR, compared with 54:01 ± 04:05 with PLA (p = 0.380). The TT performance decreased (p < 0.001), and Tc (p < 0.001) and Tsk (p < 0.001) were higher in hot compared with euthermic conditions. In summary, BR supplementation has no significant effect on cycling TT performance in the heat.  相似文献   

15.
Abstract

Strength training and positive energy intake are the most important factors related to lean body mass (LBM) gain. Most studies investigating weight-gain interventions are based recreationally active subjects and less is known about optimal weight-gain protocols in elite athletes. The purpose of this study was to evaluate the effect of nutritional guidance in an 8- to 12-week weight-gain period in elite athletes. Thirty-nine elite athletes were randomised to either a ‘nutritional counseling group’ (NCG, n=21, 19.1±2.9 years, 70.9±8.9 kg) or ‘ad libitum group’ (ALG, n=18, 19.6±2.7 years, 75.0±5.9 kg). All athletes continued their sport-specific training which included an additional four strength-training sessions per week. NCG followed a meal plan providing a positive energy balance, while the ALG athletes had an ad libitum energy intake. Body weight (BW), body composition, one repetition maximum (1RM), 40 m sprint and counter movement jump (CMJ) were measured pre- and post-intervention. Energy intake was higher in the NCG than in the ALG (3585±601 vs. 2964±884 kcal) and consequently BW increased more in NCG than in ALG (3.9±0.6% vs. 1.5±0.4%). Fat mass (FM) increased more in NCG than in ALG (15±4 vs. 3±3%), but gain in LBM was not different between groups. All 1RM results improved in both groups (6–12%), whereas 40 m sprint and CMJ remained unchanged, except for a significant decrease in 40 m sprint for the athletes in NCG. Athletes with nutritional guidance increased BW more, however, excess energy intake in a weight-gain protocol should be considered carefully due to undesirable increases in body fat.  相似文献   

16.
Abstract

The aim of this study was to analyse the pacing strategies adopted by elite male and female marathon runners when setting every world record since 1998. For data analysis, the total distance of the marathon was divided into eight sections of 5?km and a final section of 2.195?km, and the relative average speed of each section was calculated individually. Female athletes maintained similar speeds in the first and second half of the marathon (ES?=?0.22, small effect, p?=?0.705), whereas male athletes increased their speed as the marathon progressed (ES?=?1.18, moderate effect, p?=?0.011). However, no differences were observed between men and women in either the first (ES?=?0.56, small effect, p?=?0.290), or in the second half of the marathon (ES?=?0.60, moderate effect, p?=?0.266). When comparing the women’s world records (1998–2003) vs. men’s records (1998–2018) by sections, we observed differences at the beginning of the race (second section, ES?=?0.89, moderate effect) and at the end (last section, ES?=?0.87, moderate effect). The pace variations during the race were similar between male athletes and that of women with male pacemakers (1.53%?±?0.60 vs. 1.68%?±?0.84, respectively). However, a trend towards higher pace variations during the race in the female records with female pacemakers was observed (2.28%?±?0.95). This study shows how male and female marathon records in the last 20 years have been set using different pacing strategies. While men used a negative strategy (faster finishing), women used a less uniform pacing strategy.  相似文献   

17.
The effects of sodium phosphate and caffeine supplementation were assessed on repeated-sprint ability. Using a randomised, double-blind, Latin-square design, 12 female, team-sport players participated in four trials: (1) sodium phosphate and caffeine, (2) sodium phosphate and placebo (for caffeine), (3) caffeine and placebo (for sodium phosphate) and (4) placebo (for sodium phosphate and caffeine), with ~21 days separating each trial. After each trial, participants performed a simulated team-game circuit (4 × 15 min quarters) with 6 × 20-m repeated-sprints performed once before (Set 1), at half-time (Set 2), and after end (Set 3). Total sprint times were faster after sodium phosphate and caffeine supplementation compared with placebo (Set 1: P = 0.003; Set 2: d = ?0.51; Set 3: P < 0.001; overall: P = 0.020), caffeine (Set 3: P = 0.004; overall: P = 0.033) and sodium phosphate (Set 3: d = ?0.67). Furthermore, total sprint times were faster after sodium phosphate supplementation compared with placebo (Set 1: d = ?0.52; Set 3: d = ?0.58). Best sprint results were faster after sodium phosphate and caffeine supplementation compared with placebo (Set 3: P = 0.007, d = ?0.90) and caffeine (Set 3: P = 0.024, d = ?0.73). Best sprint times were also faster after sodium phosphate supplementation compared with placebo (d = ?0.54 to ?0.61 for all sets). Sodium phosphate and combined sodium phosphate and caffeine loading improved repeated-sprint ability.  相似文献   

18.
This study aimed to analyse fatigue-induced changes in mechanical sprinting properties during a specific repeated-sprint test in elite rugby sevens athletes. Twenty elite rugby sevens players performed ten 40?m sprints on a 30?s cycle with participant’s running back and forth in a marked lane. Radar was used to assess maximal overground sprint performance over each 40?m. Macroscopic mechanical properties (maximal horizontal force (F0), maximal horizontal power (Pmax), maximal ratio of horizontal force (RFpeak), decrease in the ratio of horizontal-to-total force (DRF), total force and maximal sprinting velocity (v0)) were drawn from horizontal force velocity relationships, using a validated method applied to the speed–time data. Fatigue-induced changes were analysed comparing the first sprint to an average of 2nd-4th, 5th-7th and 8th-10th. Repeated-sprint ability (RSA) testing induced substantial changes in the maximal velocity component, with a decrease (–15%) in v0 (effect size (ES)?=?–2.46 to –4.98), and to a lower extent (–5.9%) in the maximal force component F0 (ES?=?–0.59). DRF moderately decreased (14%; ES=–0.76–1.11), and RFpeak largely decreased in the later sprints (ES?=?–0.32 to –1.27). Fatigue observed in this RSA test appeared to have a greater effect on the technical ability to produce horizontal force at high velocities, likely due to an alteration in the ability to maintain horizontally oriented force application when velocity increases rather than during the initial acceleration phase, but also the overall force production capacity. The ability to maintain forward-oriented force at high velocities is of central importance for identifying fatigue and monitoring load.  相似文献   

19.
Background: Prolonged strenuous exercise has a profound effect on cardiac function. The right heart may be more susceptible to this imposition; yet, right-sided chest leads have not been utilised in this setting. Methods: Thirty highly trained athletes at the 2014 Western States 100-mile Endurance Run from Squaw Valley to Auburn, California (body mass 68?±?12?kg, age 45?±?10?years, 57?±?15?miles per week) were recruited for the study. Pre- and post-race, a right-sided 12-lead ECG was obtained and data were extracted for P, R and S waves, J point, ST segment and T wave amplitude. Data were compared using Students T-test and statistical significance set as P?Results: There was a significant increase in P wave amplitude (29%) and QTc interval (4%) pre- to post-race from standard 12-lead ECG. From the right-sided12-lead ECG, a 23% (P?=?.01) and 38% (P?=?.03) increase in J point amplitude in V1R and V2R and a 22% (P?=?.05) increase in ST segment integral in V2R and V3R were evident. T wave inversion was evident in leads V2R–V6R in 50–90% of athletes, respectively. Close examination revealed marked heterogeneity in individual ECGs. Conclusions: Completion of a 100-mile ultra-marathon resulted in significant changes in the right-sided ECG alongside more marked responses in specific individuals. P wave, ST segment and T wave changes post-race are indicative of acute exercise-induced right heart electrical adaptation.  相似文献   

20.
This study examined the effects of beetroot juice on the repeated bout effect (RBE) to eccentric exercise. Twenty-nine recreationally active males performed two bouts of 100-drop jumps, separated by 14–21 days. Using a double-blind, independent groups design, participants consumed either a higher dose beetroot juice (H-BT; 250 ml, n = 10), a lower dose beetroot juice (L-BT; 125 ml, n = 9) or an isocaloric placebo (PLA; 250 ml, n = 10) for 3 days after bout 1; no drinks were consumed after bout 2. Maximal isometric voluntary contraction (MIVC), countermovement jump (CMJ), pressure-pain threshold (PPT) and creatine kinase (CK) were measured pre, post, 24, 48 and 72 h following both bouts. In bout 2, CMJ and MIVC recovered quicker and CK activity was attenuated (versus bout 1) (P < 0.05) in all groups, demonstrating an RBE. At 24 h post bout 1, MIVC was 84.1 ± 16.1, 83.6 ± 11.6, 79.7 ± 15.1% relative to baseline values in the H-BT, L-BT and PLA groups, respectively; at 24 h post bout 2, MIVC recovered to 90.7 ± 13.7, 92.9 ± 6.9, 87.8 ± 6.9, in the H-BT, L-BT and PLA groups, respectively. These findings suggest that supplementation with antioxidant-rich beetroot juice does not adversely affect acute adaptations to a bout of eccentric exercise.  相似文献   

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