Should you work out when you're sick? It depends on your symptoms

Getting sick can throw off your fitness routine, and for those who love working out, that's a big bummer. It's tempting for fitness enthusiasts to continue their usual routine even while battling a cold, but certain symptoms indicate that you should allow your body to recuperate before exercising again. While regular exercise may actually boost your immune function, exercising once you're already sick isn't known to help (and it may hurt).

Note: If you feel sick, you should not work out in a gym, fitness studio or any area where you'll be in proximity to other people. Even if you only have minor symptoms, it's safest to work out at home, or go for a walk in a lightly populated area. With that in mind, here's when it's safe to exercise and when you should rest. 

Related: Exercising outside during self quarantine: The do's and don'ts

Exercising when sick: The rule of thumb

Many people follow the "above the neck" rule for exercising when sick. This guideline stipulates that if your symptoms are localized to your head (like sinus congestion), instead of widespread (like a fever), it's probably safe for you to exercise, although you may want to stay away from intense exercise until you feel well.

Though there's no real scientific evidence that shows whether the "above the neck" helps or hurts cold-like symptoms, it's a safe piece of advice that experts have been giving for years. As the Mayo Clinic says, "Let your body be your guide." If you feel too sick to exercise -- regardless of where your symptoms lie -- don't exercise.

You can safely exercise with these symptoms

If you don't feel too shabby overall, a light (key word: light) workout, such as a walk or yoga flow, may provide a much-needed respite from your symptoms. Though you can't exactly "sweat out" an illness, some research shows that moderate physical activity could shorten the length of time you have symptoms.

If you have these mild symptoms, you can safely opt for a light workout: 

• Mild headache
• Nasal congestion
• Minor sore throat
• Minor cough
• Earache (unless you're being treated for an ear infection)

You should rest if you have these symptoms

If you're experiencing symptoms of the flu or severe symptoms in general, it's probably best to give your body some time to rest and recover. Your body is already working very hard to fight off whatever's bringing you under the weather, and exercising adds unnecessary stress -- and may undermine the efforts of your immune system. 

Working out while you have the following symptoms can make things worse:

• Fever
• Chills
• Body aches
• Bad headache or migraine
• Persistent, severe cough or productive cough (one that clears mucus)
• Chest congestion
• Nausea, vomiting or an upset stomach 
• Diarrhea
• Decreased appetite or thirst
• Weakness and fatigue
• Muscle aches
• High heart rate at rest
• Chest tightness

Tips for working out while sick 

If you decide to exercise when you're sick, it's best to avoid intense activities that might result in overexertion. Instead of strenuous exercise such as sprinting, jumping, interval training or heavy weightlifting, opt for light exercise such as walking, easy biking or yoga. 

Also make sure to drink plenty of water and electrolytes to maintain fluid balance, eat nutritious pre- and post-workout meals and get plenty of sleep. 

Most importantly, don't ignore what your body tells you. If you pick up on any warning signs once you start your workout -- even if you felt OK before starting -- reduce the intensity further or stop altogether. It may feel frustrating to be thrown off your exercise routine, but you'll be happy when you come back well-rested and stronger than before.