Q: In this task, you are given a text of many news articles seperated by special token "|||||". Your task is to summarize them.
Cold weather during National Football League games doubled the risk of concussion for players in the 2012-13 and 2013-14 seasons, researchers at the University of Toronto have found. 
  
 NFL players were also 50 per cent more likely to suffer ankle injuries on game days when the temperature dipped below 10 C than when it was 21 or warmer. 
  
 The study is the first to show a link between cold weather and increased risk of injuries in pro football, said Dr. David Lawrence, lead author of the report published Thursday in the Orthopaedic Journal of Sports Medicine. 
  
 Nevertheless, he cautioned against concluding that colder weather is hazardous to players, saying it would be premature to set game-day temperature guidelines to prevent injuries. 
  
 “Additional research that either replicates or refutes these findings needs to be done before we take that next step,” said Lawrence, a clinical fellow in sports medicine at the University of Toronto and St. Michael’s Hospital. 
  
 Pro football is arguably the roughest of all major pro sports. Previous research by Lawrence found the overall risk of injury in the NFL was about three times higher than in professional rugby, and 25 times higher than in the NHL. 
  
 In this latest study, Lawrence and colleagues set out to identify risk factors for the five most common locations of injury in NFL players: knee, ankle, hamstring, shoulder and head (concussion). 
  
 The impetus for the research was to evaluate how the NFL’s proposal to expand its geographic borders might affect players’ injury risks. Changes in the NFL would require teams to travel greater distances to countries with different climates and altitudes, across a broader range of time zones. 
  
 In their analysis, however, the researchers found no relationship between injury risk and a change in time zone prior to a game, distance travelled to a game or how late in the season the game was played. Nor did factors such as the game’s importance, outcome or altitude seem to affect injury risk. 
  
 The researchers did find that shoulder injuries increased about 40 per cent when teams played on grass instead of synthetic turf. Players may be more likely to lose their footing on grass, which tends to be more uneven, Lawrence said. He added that newer forms of synthetic turf have improved shock-absorbing properties and may help soften direct impacts to shoulders. 
  
 The association between cold weather and injuries is more difficult to explain, he said. Lawrence speculated that, in warmer weather, athletes may mistake the symptoms of concussion for heat stroke and fail to report them. In colder weather, athletes may be more likely to use hand-warmers, hot drinks and warm coats on the sidelines, and therefore have more interaction with training staff who recognize symptoms of concussion. He added that playing surfaces and sports equipment may become less elastic at colder temperatures, increasing the force to the head during impact. “But that hasn’t been proven,” he said. 
  
 There may be a physiological explanation for why cold weather may increase the risk of concussions, said Dr. Will Panenka, a neurologist and psychiatrist at the University of British Columbia who specializes in traumatic brain injury. In colder temperatures, “your whole body is more tense and you might not fall the right way,” he said. “Your neck may not be as amenable to stretching, so the impact is more to your head.” 
  
 Lawrence and colleagues are conducting a follow-up study using a larger data set over five years to see whether the link between cold weather and increased risk of injury for NFL players remains. “If that does turn out to be a true finding,” he said, the data could be relevant to rugby, soccer or “any outdoor sports that are played in different temperatures.” 
  
 Report Typo/Error ||||| THURSDAY, March 31, 2016 -- NFL players are more likely to suffer concussions and ankle injuries during games played on colder days, a new study finds. 
  
 Canadian researchers analyzed data on the five most common injuries that occurred during two National Football League seasons between 2012 and 2014. 
  
 Players had twice the risk of concussion and a 1.5 times higher risk of ankle injuries when the temperature was 50 degrees Fahrenheit (10 degrees Celsius) or colder, compared to games played in 70 degrees (21 degrees Celsius), the findings showed. 
  
 The researchers also found that players were 1.36 times more likely to suffer shoulder injuries during games played on natural grass instead of synthetic turf. 
  
 "There has been a lot of discussion recently about the significant risk of injury in the NFL and general player safety, particularly regarding concussions," said lead study author Dr. David Lawrence, a clinical fellow at St. Michael's Hospital in Toronto. 
  
 "The first step in improving player safety and lowering that risk is to identify the factors affecting injury rates. Once we can answer those questions, we can begin to modify player exposure," he said in a hospital news release. 
  
 "There is limited research looking at the external risk factors for injuries in the NFL," Lawrence said. "Given this is one of the first studies to look at these variables, we can only speculate at this time on the underlying causes for the associations we observed with specific injuries on game days." 
  
 For example, equipment may have less give at colder temperatures, which may increase the force of impact, the researchers suggested. Players may be more likely to report injuries during colder games because they tend to have more contact with athletic staff when it's colder. It's also possible that in warmer weather, players may mistake concussion symptoms for heat-related illness. 
  
 "Our findings contribute to the growing body of evidence surrounding this topic, but further research is needed," Lawrence said. 
  
 "Applying this information may help inform future injury prevention strategies in the NFL, or other professional sports, and highlight the effects of these seemingly small external factors," he added. 
  
 The study was published in the March 31 issue of the Orthopaedic Journal of Sports Medicine. 
  
 The American Academy of Family Physicians has more on concussion. 
  
 Copyright © 2016 HealthDay. All rights reserved. 
  
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A:
Amid the furor over concussions in the NFL, a new study finds that players are at a higher risk for the injuries during games played when it's colder out. Researchers looked at injury report data from all 32 NFL teams for the 2012-13 and the 2013-14 regular seasons, and found that during games played in temperatures of 50 degrees Fahrenheit or lower, players had double the risk of concussions compared to those in games played at around 70 degrees or warmer. There was also a 1.5 times higher risk of ankle injuries in the colder games, and a 1.36 times higher rate of shoulder injuries for players in games on natural grass (as opposed to synthetic turf), UPI reports. The Canadian researchers say this is the first study to show such a link with the weather, notes the Toronto Globe and Mail. The study did not identify why the higher risk exists, but "at colder temperatures, materials and equipment in the playing environment have a lower elastic potential, and that may increase the impact forces that are transmitted during the game and increase forces to the head," the lead author says. It's also possible that concussions are simply under-reported for games at warmer temperatures, since players might incorrectly believe they are simply dehydrated or overheated. During colder games, athletic staff might be more quick to realize concussion symptoms, because they are interacting with players more often to keep them warm on the sidelines. As for the ankle injuries, the lead author says it's possible bodily reflexes don't work as well in the cold, making injuries more likely. (A new report on the NFL's concussion research is quite damning.)