Much has been made of the cold weather expected for three of the four playoff games this weekend, particularly in Green Bay, where the projected forecast for Sunday’s 49ers-Packers game is single-digit temperatures with wind chill in the minus-20s. In addition to the usual injury risks associated with playing a collision sport, there are concerns with playing in frigid conditions. The medical personnel responsible for caring for these athletes will be on the lookout for certain factors that could signal distress associated with the cold, particularly because players may not readily identify when problems start to occur.

“The bigger concerns in these extreme cold conditions are more of the non-orthopedic medical conditions, especially the risk of frostbite,” said Dr. Matt Matava, head team physician for the St. Louis Rams and president of the NFL Physicians Society. Exposed areas such as ears, noses and fingers are at greatest risk for players, who may already have diminished sensation in the cold and may not realize they have an issue. In particular, medical staff must monitor for signs of frostbite. “If an area is not turning pink in the cold, but instead turns white, it indicates that blood is not flowing to the area,” noted Matava, adding that the staff must then take immediate measures to try to warm the area.

Packers RB Eddie Lacy will have more than just the 49ers' defense to deal with on Sunday. Lacy's asthma could pose difficulties in what is expected to be brutally cold weather in Green Bay. AP Photo/Ben Margot

It’s especially important for players to keep hands, feet and faces warm in frigid conditions. To that end, teams use hand warmer packs that are ripped open and then placed inside gloves or even shoes. Space heaters and heated benches on the sidelines are essential, along with the standard cold-weather gear such as parkas and hoods. Interestingly, it’s important for players to keep a helmet on. “Normally you lose up to 20 percent of your heat through your head,” Matava said, “so wearing a helmet actually really helps.”

Other protective measures for players include Vaseline or another petrolatum-based product on the skin, including along the arms for those who insist on going sleeveless. Gore-Tex materials underneath uniforms help wick away moisture and maintain heat. Underneath their playing gloves, some players will even wear skin-tight surgical gloves, which allow movement and add another layer of protection and heat retention.

Frostbite isn’t the only cold-weather worry. While it’s easy to imagine dehydration being an issue in hot, humid environments, Matava said it is just as big a concern in cold-weather situations, perhaps an even greater one because it may be overlooked by athletes. “In the cold, athletes lose a significant amount of water through the mist they exhale during breathing,” he said. “Metabolism is higher as the body tries to maintain body heat and the athletes need to maintain their hydration.” Water and Gatorade are obvious choices to combat hydration, but cold drinks in extreme cold aren’t particularly appealing. A solution? “Chicken broth,” Matava said. “Not only is the chicken broth warm, it has salt to help replace what is lost in sweat.”

In extreme cold, muscle strains are common. Maintaining flexibility in the cold is difficult, said Matava, especially for players who don’t play every down. Bench warmers and exercise bikes on the sideline come in handy for players during down time. Joints, especially smaller ones in the fingers, get stiff and don’t move as easily, making ball handling more challenging. Add to that the fact the football itself becomes harder in the cold and routine things such as snaps, catches and defensive batting of balls become riskier to fingers. Many players will opt to wear gloves for this reason, but the risk of fractures in the hand still goes up in cold. Matava said the ground also tends to become slicker in extreme cold and equipment managers will counter this by adjusting cleat length depending on the field conditions.

Outside of the musculoskeletal conditions, medical conditions such as asthma can become more problematic in dry, cold weather. Cold air can cause bronchospasms, exacerbating an asthmatic condition for players who have a history of this and may be more predisposed to an episode. “Teams will keep inhalers on the sideline for players who develop any wheezing or breathing issues, but staying hydrated is also a component of helping control the asthma,” Matava said.

While there is no specific data to support the notion that there is any definitive increase in orthopedic injury risk in cold weather, Matava believes there may indeed be an advantage for those players, even from a psychological standpoint, who are accustomed to training and playing in the cold.

Saturday:

Kansas City Chiefs at Indianapolis Colts, 4:35 ET: As Colts owner Jim Irsay noted on Twitter, the dome is expected to be 72 degrees at game time. Just right.

New Orleans Saints at Philadelphia Eagles, 8:10 ET: Winter storm Hercules unloaded snow early enough for the team to clear the field. The temperature is expected to be in the low 20s, with very light winds. Cold-weather precautions are important, but the lack of significant wind will help.

Sunday:

San Diego Chargers at Cincinnati Bengals, 1:05 ET: At first glance, the projected temperature of 39 degrees doesn’t seem hazardous. But the wind-chill estimate (minus-7 degrees) and the 100 percent chance of precipitation (which appears to be a likely mix of rain and snow) and the forecast looks a lot uglier. Bengals receiver A.J. Green, who had a knee injury that kept him out of practice Wednesday, is listed as probable. If the precipitation is significant, he could be affected. Cincinnati tight ends Tyler Eifert (neck) and Jermaine Gresham (hamstring), both of whom missed the regular-season finale, are listed as questionable. Both have a chance to play, but given the high rate of recurrence of hamstring injuries (nearly 30 percent), the weather conditions could be problematic for Gresham.

San Francisco 49ers at Green Bay Packers, 4:40 ET: Without a doubt, this appears to be the game most likely affected by the weather. The high is expected to be 4 degrees, with a wind chill of minus-23 degrees. Precipitation isn’t expected, but the arctic cold will be challenging. The coldest NFL game on record is the 1967 NFL Championship between the Packers and the Cowboys when the the temperature was minus-13 degrees. Those ice box-like conditions were approached only one other time at Lambeau Field, in the 2007 NFC Championship, when the reading was minus-1. As ESPN.com’s Packers reporter Rob Demovsky notes, the projected temperature for this weekend’s game is so unfamiliar, even to regular Packers fans and players, that some players are reconsidering their decision to go sleeveless and the team is offering free coffee to fans.

Packers running back Eddie Lacy, listed as probable, has played through a right ankle injury for several weeks. His ankle, however, may not be his biggest health concern. Earlier this season, the rookie acknowledged he has dealt with asthma since childhood and that the condition is exacerbated in cold weather. It was an issue for him in a late November game in which the temperature hovered around 20. He will be closely monitored by the medical staff. The cold weather could also affect 49ers cornerbacks Carlos Rogers and Eric Wright, both of whom are listed as questionable. Rogers strained his right hamstring in Week 17, and although an MRI deemed the injury non-severe, the short turnaround between games is difficult for a player at his position, even with a mild injury. Wright aggravated his hamstring during Thursday’s practice but was able to return Friday.