Apart from rare circumstances like this weekend, Israel’s winter shouldn’t prevent you from taking a run outside, cycling along a bike path or getting together with the gang for a neighborhood soccer match. To make sure that we do it correctly, without getting sick or risk getting injured, we’ve consulted with Muli Epstein, a physiologist and adviser at the Ribstein Center for Research, Sport Medicine and Physiotherapy at the Wingate Institute for Physical Education and Sports near Netanya.
Winter sports activity boosts the immune system and also provides a great chance to shed extra kilograms, but does it increase the chances of getting sick? The answer is a bit complicated.
“Studies have shown that exposure to cold air encourages white blood cell activity that temporarily suppresses and harms the activity of the immune system, as a result of increased concentrations of the hormone cortisole, which is secreted in response to sudden exposure to cold and that harms the immune system,” says Epstein. “That’s at least partially why feeling cold during training increases our chances of getting sick but overheating doesn’t involve a similar risk.
“On the other hand, regular exposure to cold enables the immune system to get used to the new climatic conditions and in the process boosts immunity. It’s important to note that we’re talking here about moderate exposure and not the kind of cold that would cause the body to lose substantial heat [hypothermia]. Researchers have discovered that controlled and continuous exposure to cold improves the functioning of certain proteins in the immune system. Therefore, training over time in cold weather conditions or in cold water dulls the response of the suppressor cells. In other words, people who exercise regularly in these conditions curb the decline in immune system functioning following the exercise compared to people who are exposed to cold on an irregular basis,” Epstein said.
So does that mean that anyone who has not regularly exercised up to now is therefore taking a risk by starting to exercise in winter weather?
“Sudden exposure to cold, especially for those in poor physical shape who don’t exercise − and/or in situations in which the immune system is compromised (due to fatigue, poor nutrition, emotional stress, dehydration or illness) − is liable to increase the risk of getting ill, particularly if the person is exposed to illness-causing viruses. Anyone who decides to start exercising outside has to be sure to follow a few basic rules: Choose appropriate clothing and avoid staying in the wind and cold after finishing the activity when your clothing and hair are wet.”
Why is the winter season a great time for people who want to lose weight?
“The human body functions at its best in a rather narrow range of temperatures. The moment we feel cold, the body increases the rate at which [bodily] substances are exchanged to prevent a drop in its core temperature. When we feel cold we start to shiver, and that’s the result of rapid contraction and relaxation of muscles. The role of our shivering is the produce heat to maintain our body’s core temperature. Involving our muscle system to maintain temperature requires expenditure of energy, and as a result we ‘waste’ more energy than we do when we’re at rest and things are comfortable. The energy sources we use to boost metabolic heat production are carbohydrates and fat.”
Are there risks involved in exercising in winter conditions?
“In cold weather, muscles tend to get pulled more and be stiffer, especially when our skin is exposed to the cold air. That’s why the chance of injury increases in the cold, especially among athletes who have to perform strenuous activity and sprints. Our muscles perform better when they’re warm, and that, of course, is one of the reasons why we should do warm-up exercises before undertaking sports activities. In addition, it’s important to pay attention to the fact that in cold weather our sensation of thirst becomes less sensitive. Therefore it doesn’t take long to lose a lot of fluids and become dehydrated. There is a decline in the body’s ability to perform and a lessening of the body’s ability to maintain its temperature. We should be careful to consume liquids and not let the weather obscure the need to drink. It’s very helpful to drink hot liquids that contribute to the body’s sensation of warmth.”
Are there outside temperatures or extreme conditions in which we should avoid sports activity?
“Particularly stormy weather is not the ideal time to engage in physical activity, especially if you don’t need to do so. Because our country doesn’t have many stormy days, it’s better to restrain ourselves or choose a window of opportunity in which the weather is improved somewhat. If you are used to regular outdoor physical activity and the weather isn’t conducive, choose an indoor activity.”