SciCombinator

Discover the most talked about and latest scientific content & concepts.

Journal: International journal of sports physiology and performance

28

The present study examined the effects of 24 h travel west across 11 time-zones on subjective jet-lag and wellness responses, together with self-reported sleep and upper respiratory symptoms in eighteen professional rugby league players. Measures were obtained one or two days prior to (Pre), and two, six and eight days following travel (Post 2, 6 and 8) from Australia to the United Kingdom for the 2015 World Club Series. Compared to Pre, subjective jet-lag remained significantly elevated on Post 8 (3.1 ± 2.3); p<0.05, d>0.90), though was greatest on Post 2 (4.1 ± 1.4). Self-reported sleep onset times were significantly earlier on Post 2 compared to all other time points (p<0.05, d>0.90) and large effect sizes suggested wake times were earlier on Post 2 compared to Post 6 and 8 (d>0.90). While significantly more upper respiratory symptoms were reported on Post 6 compared to Pre (p<0.05, d>0.90), no incidence of injury and negligible changes in wellness and muscle strength and range of motion (p>0.05, d<0.90) were evident following travel. Results suggest that westward long-haul travel between Australia and the United Kingdom exacerbates subjective jet-lag and sleep responses, along with upper respiratory symptoms in professional rugby league players. Of note, the increase in self-reported upper respiratory symptoms is a reminder that the demands of long-haul travel may be an additional concern to jet-lag for travelling athletes. However, due to the lack of sport-specific performance measures, it is still unclear whether international travel interferes with training to the extent that subsequent competition performance is impaired.

Concepts: United Kingdom, Respiratory system, England, Travel, Football, Rugby league, Rugby football, Rugby League World Cup

28

This study investigated whether there is a correlation between time-trial performance and competitive performance capacity of male and female junior cross-country skiers and sought to explain sex-specific competitive performance capacity through multiple-regression modeling.

Concepts: Male, Female, Time trial

27

Recent studies have brought new insights into the evaluation of power-force-velocity profiles in both ballistic push-offs (e.g. jumps) and sprint movements. These are major physical components of performance in many sports, and the methods we developed and validated are based on data that are now rather simple to obtain in field conditions (e.g. body mass, jump height, sprint times or velocity). The promising aspect of these approaches is that they allow for a more individualized and accurate evaluation, monitoring, and training practices; the success of which are highly dependent on the correct collection, generation and interpretation of athletes' mechanical outputs. We therefore wanted to provide a practical vade mecum to sports practitioners interested in implementing these power-force-velocity profiling approaches. After providing a summary of theoretical and practical definitions for the main variables, we have first detailed how vertical profiling can be used to manage ballistic push-off performance with emphasis on the concept of optimal force-velocity profile and the associated force-velocity imbalance. Further, we have discussed these same concepts with regards to horizontal profiling in the management of sprinting performance. These sections have been illustrated by typical examples from our own practice. Finally, we have provided a practical and operational synthesis, and outlined future challenges that will help in further developing these approaches.

Concepts: Concept, Interpretation, Sprint, Jump, Jump, South Yorkshire

27

This study aimed to determine whether biomechanical characteristics such as ground contact time, swing time, stride length and frequency contribute to the exceptional running economy of East African runners.

Concepts: Music, Height, Jazz, Swing Time

27

The aim of our study was to quantify the effects of a 12-week isolated core training programme on 50-m front crawl swim time and measures of core musculature functionally relevant to swimming.

Concepts: Swimming

27

This work examines pacing among the most successful runners in the 161-km Western States Endurance Run (WSER) to determine if variations in segmental speed relate to performance, ambient temperature and calendar year.

Concepts: Western world, Western States Endurance Run

27

Recently, an adaptation to the critical power (CP) model has been published, which permits the calculation of the balance of W' remaining (W'BAL) at any time during intermittent exercise. As the model is now in use in both amateur and elite sport, the purpose of this investigation was to assess the validity of the W'BAL model in the field. Data were collected from the bicycle power meters of 8 trained triathletes. W'BAL was calculated and compared between files where subjects reported becoming prematurely exhausted during training or competition and files where the athletes successfully completed a difficult assigned task or race without becoming exhausted. Calculated W'BAL was significantly different between the two conditions (p < 0.0001). The mean W'BAL at exhaustion was 0.5 ± 1.3 kJ (95% CI = 0 - 0.9 kJ), whereas the minimum W'BAL in the non-exhausted condition was 3.6 ± 2.0 kJ (95% CI = 2.1 - 4.0 kJ). Receiver-operator characteristic (ROC) curve analysis indicated that the W'BAL model is useful for identifying the point at which athletes are in danger of becoming exhausted (area under ROC curve = 0.914 (SE: 0.05, 95% CI: 0.82 - 1.0, p < 0.0001). The W'BAL model may therefore represent a useful new development in assessing athlete fatigue state during training and racing.

Concepts: Fatigue, Receiver operating characteristic

26

To analyze the match running profile, distance travelled over successive 15 minutes of match-play, heart rates and effindex of professional soccer players with Global Positioning System (GPS) and heart rate (HR) in official competition.

Concepts: Navigation, Global Positioning System, Global navigation satellite system, GPS, Positioning system, Wide Area Augmentation System, Navigational equipment

26

There is interest in including recommendations for the replacement of the sodium lost in sweat in individualized hydration plans for athletes.

Concepts: English-language films

25

The effects of an enforced fast-start on long distance performance are controversial and seem to depend on the athlete’s capacity to delay and tolerate metabolic disruption. The aim of this study was to investigate the effects of an enforced fast-start on 10-km running performance and the influence of the some physiological and performance variables on the ability to tolerate an enforced fast-start during the running. Fifteen moderately-trained runners performed two 10-km time-trials: free-pacing (FP-TT) and fast-start (FS-TT). During FS-TT, speed during the first kilometer was 6% higher than in FP-TT. Maximal oxygen uptake (VO2max), peak velocity (PV), velocity associated with VO2max (vVO2max), ventilatory threshold, and running economy (RE) at 10 km·h-1, 12 km·h-1 and FP-TT average velocity (AV-10 km) were individually determined. There were no differences between FP-TT and FS-TT performance (45:01 ± 4:08 vs 45:11 ± 4:46 min:s, respectively, p=0.4). We observed that eight participants improved (+2.2%) their performance and were classified as positive responders (PR) and seven decreased (-3.3%) performance and were classified as negative responders (NR). Running speed was significantly higher for PR between 6 km and 9.2 km (p<0.05) during FS-TT. In addition, PR presented higher PV (p=0.02) and vVO2max (p= 0.01) than NR, suggesting the PV and vVO2max might influence the ability to tolerate a fast-start strategy. In conclusion, there was an individual response to the enforced fast-start strategy during 10-km running, and those who improved performance also presented higher vVO2max and PV, suggesting a possible association between these variables and response to the strategy adopted.

Concepts: Kilometre, Performance, Velocity, Exercise physiology, Running, Speed, VO2 max, Running in Ancient Greece