Is running in the cold good or bad for you? Well, an interesting study published in PLoS ONE suggests it can be a mixed bag.
First, some good news for those looking for excuses not to head out in the cold. The researchers found that going straight out and exercising in cold conditions reduced the body’s natural immune functionality, making you less resistant to illness.
The flip side to this was that the researchers found that runners whose warm-up ritual involved some low-intensity shivering actually got a boost to their immune system after exercise. As Runners World points out, this means you can actually be pretty grateful for the time spent shivering in the cold waiting for a marathon to start: it might well be doing your immune system a favor.
The study followed nine male participants exercise on treadmills at two different temperatures, wearing shorts and tee-shirts. Blood samples were taken to measure each man’s immunological and endocrine changes.
The pre-run shivering was induced by having participants sit in a cold chamber for 40 minutes to two hours before hitting the treadmill. They reckon the boost to the immune system is from increased norepinephrine induced by this period – it’s a neurotransmitter which makes up part of the ‘fight-or-flight’ response. They did stress, however, that the boost can only be claimed for ‘low level’ shivering – more extreme forms of cold would likely have a different response.
An interesting side-note to the research. In an email to Runners World, the paper’s author Dr. Dominique Gagnon explained that colder runners used more fat, which should preserve the muscle’s limited glycogen stores. “Plainly said, sugar is your fast easy-go-to fuel during exercise but it is present in much lower quantity than fat. Therefore if you can enhance the use of fat as fuel, you are saving some of the sugar for later and can prevent early fatigue during exercise. In [an] ideal world, we would only use fat and consequently could run for weeks,” she wrote.