Pacing profiles and tactical behaviors of elite runners

The pacing behaviors used by elite athletes differ among individual sports,necessitating the study of sport-specific pacing profiles.Additionally,pacing behaviors adopted by elite runners differ depending on race distance.An“all-out”strategy,characterized by initial rapid acceleration and reduction in speed in the later stages,is observed during 100 m and 200 m events;400 m runners also display positive pacing patterns,which is characterized by a reduction in speed throughout the race.Similarly,800 m runners typically adopt a positive pacing strategy during paced“meet”races.However,during championship races,depending on the tactical approaches used by dominant athletes,pacing can be either positive or negative(characterized by an increase in speed throughout).A U-shaped pacing strategy(characterized by a faster start and end than during the middle part of the race)is evident during world record performances at meet races in 1500 m,5000 m,and 10,000 m events.Although a parabolic J-shaped pacing profile(in which the start is faster than the middle part of the race but is slower than the endspurt)can be observed during championship 1500 m races,a negative pacing strategy with microvariations of pace is adopted by 5000 m and 10,000 m runners in championship races.Major cross country and marathon championship races are characterized by a positive pacing strategy;whereas a U-shaped pacing strategy,which is the result of a fast endspurt,is adopted by 3000 m steeplechasers and half marathoners.In contrast,recent world record marathon performances have been characterized by even pacing,which emphasizes the differences between championship and meet races at distances longer than 800 m.Studies reviewed suggest further recommendations for athletes.Throughout the whole race,800 m runners should avoid running wide on the bends.In turn,during major championship events,1500 m,5000 m,and 10,000 m runners should try to run close to the inside of the track as much as possible during the decisive stages of the race when the speed is high.Staying within the leading positions during the last lap is recommended to optimize finishing position during 1500 m and 5000 m major championship races.Athletes with more modest aims than winning a medal at major championships are advised to adopt a realistic pace during the initial stages of long-distance races and stay within a pack of runners.Coaches of elite athletes should take into account the observed difference in pacing profiles adopted in meet races vs.those used in championship races:fast times achieved during races with the help of one or more pacemakers are not necessarily replicated in winner-takes-all championship races,where pace varies substantially.Although existing studies examining pacing characteristics in elite runners through an observational approach provide highly ecologically valid performance data,they provide little information regarding the underpinning mechanisms that explain the behaviors shown.Therefore,further research is needed in order to make a meaningful impact on the discipline.Researchers should design and conduct interventions that enable athletes to carefully choose strategies that are not influenced by poor decisions made by other competitors,allowing these athletes to develop more optimal and successful behaviors.

Radius model of convex vertical curve of freeway based on attachment coefficient

A longitudinal slope brake model was established for the radius calculation of vertical curve of freeway through analyzing the dynamics of brake-running of vehicles running on the longitudinal slope road section. To satisfy the requirement of sight distance, a relation model was established for the attachment coefficient and the convex vertical curve radius. Using MATLAB simulation technique, the convex vertical curve radius at different attachment conditions was calculated accurately and a three-dimensional figure was drawn to describe the relation between the adhesive coefficient, the driving velocity and the radius of vertical curve. The correlation between the convex vertical curve radius and the adhesive coefficient was further analyzed and compared with National Technical Standards. The suggested radius of vertical curve was then put forward to provide a theoretical platform for the security design of the convex vertical curve.

Does Acute Improvement in Muscle Recovery with Curcumin Supplementation Translate to Long-Term Training?

Dietary polyphenols,such as curcumin,green tea catechins,and pomegranate extract,may have the ability to enhance the effectiveness of long-term training programs by managing training-induced inflammation.Enhanced recovery may translate to increased capacity to train and perform more effectively.The dietary polyphenol curcumin has been reported to block the action of COX-2 and NF-kB signaling and would allow for increased capacity to train leading to heightened adaptations and the potential for ergogenic outcomes.These actions are very similar to the targeted actions of non-steroidal anti-inflammatory drugs(NSAIDs),but without the side-effects of NSAIDs.This review will compare and contrast the known effects of cur-cumin and identify common design elements between existing studies.Through this critical review of the existing literature it is our goal to establish a set of best practices that could be applied to an athletic population that is interested in using oral curcumin supplementation as a recovery agent.