Jet lag impairs performance of Major League Baseball players

A new Northwestern University study of how jet lag affects MLB players traveling across just a few time zones finds that when people, in this case Major League Baseball players, travel in a way that misaligns their internal 24-hour clock with the natural environment and its cycle of sunlight, they suffer negative consequences.

"Jet lag does impair the performance of Major League Baseball players," said Dr. Ravi Allada, a circadian rhythms expert who led the study. "The negative effects of jet lag we found are subtle, but they are detectable and significant. And they happen on both offense and defense and for both home and away teams, often in surprising ways."

In a study of data spanning 20 years and including more than 40,000 games, the researchers identified these effects of jet lag on player and team performance:

• The offense of jet-lagged home teams is much more affected than that of jet-lagged away teams. Surprisingly, in terms of offensive performance, jet lag from eastward travel had significant negative effects on home teams (after returning from a road trip) and much less of an effect on away teams.
• Negative effects on offense are related to base running. The negative effects on the home team's offense were related to base running, such as stolen bases, number of doubles and triples, and hitting into more double plays.
• Both home and away teams suffer on defense, specifically by giving up more home runs. With defensive performance, strong effects of eastward jet lag were found for both home and away teams, primarily with jet-lagged pitchers allowing more home runs. "The effects are sufficiently large to erase the home field advantage," Allada said. Besides home runs allowed, few other effects were seen on pitching or defense.
• There is a difference between traveling east and traveling west. Most significant jet-lag effects were generally stronger for eastward than westward travel. "This is a strong argument that the effect is due to the circadian clock, not the travel itself," Allada said.

The study, "How Jet Lag Impairs Major League Baseball Performance," will be published the week of Jan. 23 in the journal Proceedings of the National Academy of Sciences (PNAS).

Allada and his team, Alex Song (first author) and Thomas Severini, used an unprecedented amount of MLB data (from 1992 to 2011), which gave the researchers the statistical power to identify the effects of jet lag on offensive and defensive performance metrics. The researchers considered if teams were traveling east or west; if the team was home or away; and the team itself.

They also looked at the number of hours players would be jet-lagged, based on the number of time zones traveled across, to determine which games were "jet-lag games" and which were not. (The human body clock can roughly shift about an hour each day as it synchronizes to the new environment.) If players were shifted two or three hours from their internal clocks, the researchers defined them as jet-lagged.

What does all this data analysis mean going forward? With MLB spring training less than a month away, Allada has some advice based on his research.

"If I were a baseball manager and my team was traveling across time zones -- either to home or away -- I would send my first starting pitcher a day or two ahead, so he could adjust his clock to the local environment," Allada said.

Allada provides an example from the 2016 National League Championship Series illustrating the potential impact of jet lag on player performance. In game 2, Los Angeles Dodgers' ace Clayton Kershaw shut out the Chicago Cubs, giving up only two hits, but game 6 was a different story.
"For game 6, the teams had returned to Chicago from LA, and this time the Cubs scored five runs off of Kershaw, including two home runs," Allada said. "While it's speculation, our research would suggest that jet lag was a contributing factor in Kershaw's performance."

More sprints in top-class football necessitates new and individualized training routines

Today's top-class football is characterised by more short sprints than in the past. In English Premier League, high-intensity running has increased by 50% in the last 10 years, presenting new challenges to the players in terms of fatigue resistance and ability to recover quickly. The change has also resulted in greater variation in the tempo of matches, and this new pattern calls for revised training routines. This is the conclusion of new research from the University of Gothenburg and the University of Southern Denmark.

The study in question is based on an extensive amount of data. A research team, consisting of Dan Fransson and Magni Mohr, exercise physiology researchers at the Department of Food and Nutrition, and Sport Science, University of Gothenburg, and Professor Peter Krustrup from the University of Southern Denmark, watched 62 football matches played 2010-2012 and made 1 105 observations of 473 players from 24 different Premier League teams.

The results show that, compared with in the past, modern top-class football is characterised by more high-intensity sprints followed by a substantially lower tempo. Repeated bouts of high-intensity running for 1-5 minutes are followed by a historically low intensity for up to 5 minutes. Thus, a player's activity level during a match tends to alternate between two extremes, compared with the traditionally more steady match tempo.

Training Should Be Adapted to the New Pattern

The analysis points to significant differences in fatigue and recovery patterns among players. Some players can exhibit four times as much high-intensity running as others in one and the same match.

'This indicates that in order for players to maximise their potential and avoid injuries, they need more individualised training depending on position played. All players shouldn't train in the same way,' says Fransson.

Central defenders stand out from the other playing positions. These are the only players whose running did not decrease after the most intense 1-2-minute periods.

'The reason for this is simply that central defenders face the lowest demands of all players except goalkeepers when it comes to high-intensity running. They have the longest recovery periods between the intense phases of a football match,' says Fransson.

Could better eye training help reduce concussion in women's soccer?

With the ever-growing popularity of women's soccer, attention to sports-related concussions is also a growing concern, as the act of heading the ball is thought to contribute to increased incidence of concussion. 

"Current evidence shows that high school female soccer players incur a higher concussion rate than males," says Joe Clark, PhD, professor in the Department of Neurology and Rehabilitation Medicine at the University of Cincinnati College of Medicine. "While this is often attributed to gender differences in physical build or neck muscle strength, our study suggested that there might be other behaviors such as field awareness that are contributing factors that result in these higher concussion rates."

Researchers working with Clark observed that in photographs of female soccer players during play, the players often had their eyes closed while heading the ball. They wanted to quantify whether female athletes closed their eyes more frequently than male counterparts, as a first step toward determining if less visual awareness might expose players to a higher risk of injury. Their results of the first part of this study are have been published in the online version of Medical Hypotheses.

Through an analysis of Google images of soccer headers by both male and female players in active game play, 100 images of each gender were reviewed and categorized. Some images showed more than one athlete participating in the header, what some people may call a 50-50 ball.

Of 170 females identified in the photos, 90.6 percent of them were shown to have their eyes closed during play. By comparison, 79 percent of male players had their eyes closed, of the 170 male athletes evaluated in the photos. 

These findings indicated that female players were more likely to close their eyes at the act of heading the ball, versus males. Vision training methods in other concussion-prone sports like football work to train the athletes to use visual tactics to be aware of the ball and aware of other players prior to a hit something the researchers refer to as "eye discipline." 

It is felt that better eye discipline may account for the difference in concussion rates between males and females. "In other studies, vision training has successfully reduced the rates of concussion in college football athletes; overall lack of visual awareness in a contact sport may increase the risks of concussion. Therefore vision training and better eye discipline may decrease concussion rates." 

Clark, who works with high school and college-level athletes on vision training techniques to improve their awareness in avoiding hits on the field, says that with practice, athletes can learn to play safer. "The startle reflex, or blinking or closing one's eyes upon a perceived risk, can be suppressed through training and coaching. So it is possible that training to improve eye discipline and maintain control of ball handling, may help mitigate concussions in soccer players heading the ball," he says.

Hagar Elgendy, a medical student at the UC College of Medicine, and a co-author of the study, has been involved with the sports medicine research at UC for the past few years. "Concussion in sport has gained much attention recently. It was exciting and interesting to be involved in this project and to propose a hypothesis for the greater concussion incidence in the high school athletic setting for females over males." Elgendy, along with her sister, Hanna Elgendy, worked to obtain and analyze the Google images for the study.

Clark says, "We hope to follow up with larger future studies as to whether eyes closed upon impact correlate with higher rates of concussion, to validate this hypothesis."

Top-level football refs are better at spotting fouls because of enhanced visual perception

Top-level professional football referees have enhanced visual perception, which means that they are better at spotting foul play and issuing the correct disciplinary action than lower-level referees, according to new research published in the journal Cognitive Research.

The researchers, from Belgium and the UK, had 39 football referees from the top and lower leagues in Belgium watch staged videos of fouls being committed from the point-of-view of a referee on the football pitch. Eye-tracking technology was used to assess their visual-search behaviour - that is the location that the referees' eyes fixated on and for how long.

Professor Werner Helsen, co-lead author from the University of Leuven in Belgium, said: "Our results show that elite referees have visual-search behaviour patterns that make them better at assessing foul play situations in football compared to lower league referees. When watching open play fouls being committed, elite referees spend more time fixating on the body part involved in the foul than other areas, suggesting that they are focusing on and interpreting the most crucial information within their visual display."

Visual-search behaviour is a primary skill utilised by professional athletes that enables them to coordinate perceptual-cognitive function with motor skills. Referees also rely heavily on visual-search behaviour in order to rapidly translate what they see into a correct decision based on the rules of the game. When asked to state if they thought the open-play foul committed deserved a disciplinary sanction (no card, yellow card or red card), elite referees made the correct decision with an accuracy of 61%, compared to 45% amongst lower level referees.

Dr Jochim Spitz, co-lead author, said: "Visual-search behaviour is an in-built cognitive function that can be improved through training and development. Understanding what it is exactly that makes elite referees able to make better decisions than lower-level referees could help devise training programmes specifically aimed at improving visual-search behaviour."

The video clips used in this study were filmed with the help of competitive football players who were tasked with simulating a variety of foul play scenarios including fouls in open play and from corner kicks. The action was filmed from approximately 10 meters away to mimic the proximity of a referee to the game in a real life situation. In order to make the simulations as natural as possible, no specific instructions were given to the players related to the type of foul that should be executed. A total of 20 videos were made, 10 open-play situations and 10 corner-kick situations, out of which three showed no foul play.

In the open-play and corner-kick scenarios, there was no difference between the numbers of locations that the referees focused on when watching the videos but, importantly, the elite referees did spend more time fixating on the contact zone between the attacker and the defender than the non-elite referees. Analysing the data collected from incorrect decisions made by referees, it was concluded that the fixation time plays an important role translating perceived incidents into a correct interpretation according to the 'Laws of the Game'.

Professor Werner Helsen added: "We can speculate from our results that the level of experience in elite referees is translated into long-term memory which allows their visual-search behaviour to be driven by acquired knowledge. Sub-elite referees on the other hand have less experience and seem to apply a more random control of visual fixation".

Example videos of foul play situations watched by the referees are available here: https://goo.gl/tXpNrW

Heading a football can significantly affect a player's brain function

Heading a football can significantly affect a player's brain function and memory for 24 hours, a study has found.

Researchers said they had identified "small but significant changes in brain function" after players headed the ball 20 times.

Memory performance was reduced by between 41% and 67% in the 24 hours after routine heading practice.

One of the study's authors suggested football should be avoided ahead of important events like exams.

The University of Stirling study was published in EBioMedicine.

It is the first to detect direct changes in the brain after players were exposed to everyday head impacts, as opposed to clinical brain injuries like concussion.

Researchers fired footballs from a machine designed to simulate the pace and power of a corner kick and asked a group of football players to head a ball 20 times.

The players' brain function and memory were tested before and after the exercise...

Complete article:http://www.bbc.com/news/uk-scotland-37714830?utm_source=nl-atlantic-daily-102416

Heavy hitters: Obesity rate soars among professional baseball players

CREDIT: CHRISTIE CLANCY/PENN STATE

Major League Baseball players have become overwhelmingly overweight and obese during the last quarter century, say health researchers.

David E. Conroy, Penn State professor of kinesiology, and colleagues looked at 145 years of data on professional baseball players' body mass. The researchers found that the athletes' weight held steady for over 100 years, with the majority of them weighing in at what is considered "normal," -- i.e., with a body mass index (BMI) between 18.5 and 24.9.

However, around 1991 the average player's BMI began to rise, and over the last 25 years nearly 80 percent of players fall into the overweight or obese category with a BMI above 25. Obesity in the general U.S. population began to rise in the mid-1970s, according to the Centers for Disease Control and Prevention.

"Research exists that shows how having extra weight can help with certain aspects of baseball," said Conroy, also professor of human development and family studies. "The more force a batter can put into the ball, the further it will travel."

The researchers used the publicly available Lahman Baseball Database, where players' height, weight and age are recorded for their debut year in Major League Baseball. The data were self-reported, however Conroy points to the trend of players' increasing weight as informative -- and cause for some concern.

Conroy and colleagues report their findings today (Sept. 28) in Obesity Research and Clinical Practice.

"The data are observational, and raise more questions than they answer," cautioned Conroy. "BMI can be misleading, because it doesn't take body composition into account. What kind of pounds are the players adding? Are they mostly muscle or fat?"

The rise coincides with baseball's steroid era, and steroids are known to cause weight gain in some. But the rise also lines up with advances in sports science and nutrition, which have enabled athletes to better train and fuel, helping them build muscle and endurance -- which could lead to weight gain as well.

"These trends warrant further attention because of the potential for adverse long-term health consequences in this population and those who perceive them as role models for health and human performance," the researchers wrote.

Referees add more extra time when the big teams are losing

Football (soccer) enthusiasts suspected it, but now statistics is confirming it. After analysing all the matches of the Spanish league "La Liga" from the 2014-2015 season, two experts in sports science have found that the greater the difference on the scoreboard, the less stoppage time is added to the end of the game. When the score is tighter, however, referees tend to add more stoppage time when the team in the higher division is losing.

The stoppage time added by the referee following the obligatory 90 minutes of a football match is used to compensate for time lost due to substitutions, injuries, expulsions and other incidents that arise during the game, but it seems as though other factors also play a role according to a new study.
Researchers Carlos Lago, from the University of Vigo (Spain), and Maite Gómez, from the European University of Madrid, have confirmed that referees favour the big teams by reducing the extra time when these teams are ahead on the scoreboard. In contrast, and according to an article published in the journal 'Perceptual and motor skills', referees slightly draw out the match when the big teams are losing.
To carry out the study the authors relied on data from the 380 matches played in the Spanish league during the 2014-2015 season. They then took several variables into account -such as the difference in goals on the scoreboard, the playing level of each team, the number of red and yellow cards, player substitutions, the average number of assists and fouls committed- to see if any of them had an influence on the amount of stoppage time.
After applying a statistical method (called linear regression and widely used to identify relationships between variables), it was observed that the greater the difference on the scoreboard, the less stoppage time was given by the referee. In very tight matches, nevertheless, refs tend to add more seconds when the team in the higher division is losing, and fewer seconds when they are winning. The number of red cards and fouls also cause an increase in extra time.
"The typical complaint from less powerful teams regarding how referees treat big teams better might make sense," explains Carlos Lago, "as their decisions tend to benefit the higher‑ranked teams when the scoreboard is against them. Furthermore, the more important the difference between the clubs, the greater the advantage." As the inequality between the teams decreases, because either two big teams or two small teams are playing against each other, this statistical trend disappears.
A bias that also favours local teams
Previous studies had already demonstrated that pressure from local fans also has an influence on referees when it comes to adding on more or less time. In the Spanish league, specifically, referees add 112 more seconds when the home team is losing by one goal or winning with a minimal difference.
This bias in favour of local teams was also found at football matches of the Bundesliga (Germany), Serie A (Italy), Premier League (United Kingdom), Major League Soccer (USA and Canada) and of the Campeonato Brasileiro (Brazil) leagues.
According to Lago, "what is most troubling is that the partiality of some referees for local teams and big clubs seems to have a name and surname, meaning that refs with less experience are more affected by the noise around them; there are also referees who are more or less home-biased and show a greater or lesser tendency to benefit the big teams in specific situations."
The expert in sports science concludes with some recommendations: "improve referee training and prevent subjectivity in their decisions to the extent possible, which at present have not proven to be malicious, but simply human. Additionally, technology could also help, although referee bias can decrease if they are simply aware of the role they play in the outcome of the matches."

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