What you need to know about cold weather and your health

WATCH ABOVE: Dr. Samir Gupta explains how cold weather can affect your body.

TORONTO – Does cold weather help people catch colds? A new study from Yale University suggests the cold air could make your body more susceptible to the cold virus.

The study found that the cold virus reproduces better in cooler temperatures.

“We found that the innate immune response to the rhinovirus is impaired at the lower body temperature compared to the core body temperature,” lead author, Dr. Akiko Iwasaki of the university’s School of Medicine, told the Yale News. “In general, the lower the temperature, it seems the lower the innate immune response to viruses.”

But cold air doesn’t cause colds – what causes a cold is exposure to a virus.  One thing that’s been known for some time now, is that viruses replicate a lot faster in conditions in the nasal cavity compared to the lung. The nasal cavity is a little bit colder at around 33 degrees Celsius versus the lung which is 37 degrees Celsius, and people have long suspected that enhanced replication may be related to the lower temperature.

So in this study, they took cells from the airways of mice, infected those cells with rhinovirus (the cause of the common cold), and incubated them at either 33 degrees Celsius or 37 degrees Celsius to mimic the conditions of the nose and lungs, respectively. They found that at 33 degrees, the cells had a reduced immune response to the virus, allowing it to replicate more quickly.

Although the study was done on mice, if we extrapolate it to humans, it might explain why viruses tend to infect our nasal cavities and cause colds as opposed to infecting our lungs and causing pneumonia – because the higher temperature in the lungs allows for better immunity.

Now because this study was conducted on mouse cells and because the “low” temperature was a balmy 33 degrees Celcius, it doesn’t yet prove the theory that exposure to severe winter weather might turn down the immune system and make humans generally more susceptible to colds.

Five ways cold air can affect your body

Moderate cold weather can improve cardiovascular performance

We know that a lot of people like to run and bike in the cold, and a 2007 study in the journal Medicine and Science in Sports and Exercise suggests that the body takes up more oxygen and the heart pumps more efficiently in temperatures just above freezing. This might be why studies also show that marathoners have better race times in the cold weather.

Cold weather might lead to fewer injuries among athletes

There was an interesting study published in 2003 that looked at injuries in about 6,000 NFL games over a 10 year period, and found that athletes were significantly less likely to have ankle and knee sprains and ACL injuries if they played in the cold weather.  This might have something to do with the cooling effect on the joints and joint fluids, but cold weather also reduces friction with the playing surface, which might be a more important factor.

Cold can trigger asthma attacks

Cold air is a known trigger for asthma attacks, and something I see commonly is patients who tend to flare if they combine cold air exposure with exercise.

Cold can cause COPD to flare

Patients with chronic obstructive pulmonary disease (COPD) tend to have more flares when the temperature drops, according to a 2013 study published in PLoS One. A 1998 study published in Chest also suggests patients actually feel more short of breath in the cold air, and a 1999 study in the ERJ suggested that their lung function also drops in cold weather.

Triggering Angina

Studies have long shown that patients with what’s called cold-induced angina can get attacks with cold air exposure, but according to a 2010 study published in the Canadian Journal of Cardiology, exercise at -20 degrees causes an increased strain on the heart in any patient with coronary disease.

People who have heart disease need to be really careful if they’re contemplating doing some shoveling in the winter storm ahead.