Sara Sjerven is a busy woman: when she’s not leading parenting workshops, she’s raising two active kids. But between her work and family commitments, she keeps one for herself: going for regular workouts.

“It preserves my sanity,” Sjerven says of her fitness regime in a phone interview with the Georgia Straight. “As a mom, it’s a break”¦.I love to feel strong, to feel athletic, to feel every muscle in my body. But I really need it emotionally.”

Sjerven, who teaches group classes like step aerobics, aims for four workouts a week. However, as we head into cold and flu season—which is all the more dreadful this year because of the swine flu—Sjerven acknowledges that being sick sometimes interferes with her goal.

“I might not go if I’m feeling really bad or exhausted,” she says. “I know that taking breaks and letting myself recuperate is important.”

For most people, though, the question of whether to exercise when they’re ill doesn’t have a straightforward answer.

Whether they hit the gym every other day, go for a run on their lunch breaks, or play in a community sports league, people rarely know whether it’s safe to work out when they have a nasty virus or if doing so would cause more harm than good.

Experts agree that people can follow one rule when deciding whether to tie up their shoelaces or stay home with their tissues.

“Generally, if it [the illness] is above the neck, it’s okay, but if it’s below the neck, it’s not okay,” says Kenneth Madden, a geriatric-medicine specialist and UBC assistant professor who researches exercise.

“The main reason is you don’t want to overexert if you have anything that causes a fever. Your body temperature increases when you do aerobic exercise, and if you add a fever, the risks are becoming overheated or heart attack.”

A chest cold is another case when it’s probably best to skip the gym.

“If you’ve got fluid on your chest, it means your respiratory system isn’t functioning as effectively as it should, and the heart will beat faster,” explains Ken Anderson, coordinator of Douglas College’s sport-science department. Add in the increased heart rate from aerobic exercise, and, once again, an intense cardio session could be dangerous.

There are exceptions to every rule, of course. Although sinusitis clearly occurs above the neck, people with the condition might find it too painful to exercise, Madden says.

But still, if you have that achy feeling all over your body that accompanies the flu along with a fever, it’s wise to get cozy at home. If you have a head cold with the sniffles, you likely won’t be doing any damage by working out—unless, that is, you have a habit of overdoing it.

“There’s a misconception that overtraining syndrome happens only in professional athletes,” Madden says. “In fact, they don’t get it that often because they have coaches watching out for that. But if you’re not in as good shape and you increase your activity too much, too fast, you can overtrain”¦.It happens to regular people who push too hard. If you find it overly draining, you need to back off.”

Light to moderate exercise, on the other hand, can even make you feel better afterward.

“Usually, exercise makes you feel energized,” Madden adds.

He points out that it’s impossible to “sweat out” a cold. However, a light workout likely won’t make your cold any worse.

Researchers at Muncie, Indiana’s Ball State University studied the effects of exercise on cold symptoms. They inoculated 50 people with a rhinovirus, then divided them into two groups: 25 of them ran, climbed stairs, and rode bikes for 40 minutes at 70 percent of their maximum heart rate; the other 25 remained sedentary except for walking short distances. According to the 2002 study published in the Journal of Internal Medicine, neither group suffered from more intense or prolonged cold symptoms.

“Some people may even feel somewhat relieved of their congestion due to a cold after a light workout, even if it is just temporarily,” says Geoff Bagshaw, group-exercise director at Denman Fitness and a personal trainer. “If you decide to proceed with exercise, you will want to back off the intensity of your workout and really just work for maintenance rather than trying to improve your fitness level.”

People who go to the gym to work out have another factor to consider to avoid getting sick: the equipment itself—specifically, the germs lurking on it.

“If people who exercise in weight rooms get sick, then go on to use barbells and dumbbells, all these people are coughing and sneezing on the equipment,” Anderson says.

Bagshaw, who teaches several group classes every day, has some advice for people who are committed to exercise and want to stay healthy: it is crucial to take care of themselves.

“I make a very conscious effort to eat healthy the majority of the time, trying to incorporate as many of the so-called super foods into my diet as possible, get enough sleep, and build in recovery days,” Bagshaw says.

“You know your body best, and it is even more important to listen to it when you are sick,” he adds. “You will know if you have the energy to work out or not. If you do attempt some exercise and feel like your symptoms are exacerbated, then ease off or discontinue your workout until you are feeling 100 percent again.

“Workout junkies often have a hard time forgoing exercise, even when they are sick. Keep in mind, though, if you have really come down with something, you aren’t doing yourself—or anyone else at the gym, for that matter—any good by working out.”

Carl Peterson, a partner at City Sports and Physiotherapy Clinics, agrees that it’s vital to pay close attention to how you’re feeling.

“You must respect the warning signs your body is sending you,” says Peterson. “Never exercise when you feel overly fatigued, nauseous, or have a fever. Always speak to your doctor regarding any health and fitness concerns. Abnormal fatigue, pain, soreness, or stiffness need to evaluated by an appropriate health care professional. Always exercise within your comfort level.”