There are obviously different levels and kinds of sickness so it really depends on how sick you actually are. It also depends on what sort of workout you plan to do, for example, weight lifting, running, playing a sport and so on.
Cold or Flu Symptoms
If you just have a bit of a cold then there should be no reason why you can’t hit the gym like you normally would. However if things are a bit more serious like suffering from a fever then it is recommended to avoid the gym and rest. Fevers cause our body temperatures to rise and it can also cause dehydration, working out will only increase these symptoms, possibly making us even more sick. If you have a fever just rest and keep hydrated until the fever has passed.
It can be difficult for some of us to give the gym a miss, it becomes additive, a habit that is hard to break, however when sickness strikes sometimes we need to rest our bodies.
Sometimes a compromise will be the best solution, for example you may be feeling well enough to have a light workout. Your body may not be able to cope with your usual level of workout intensity, so a light workout may be suitable. You could reduce your workout time, use lighter than normal weights or go for a walk instead of the usual run.
If your sickness is effecting your breathing, bad chesty cough or a swollen or sore throat for example, then you should definitely give it a miss until the symptom subside.
Another reason to give the gym a miss would be because gyms are full of hot sweaty people which means they are full of germs. Your immune system may be weaker than normal because your body is fighting off your current illness. This may mean you are more susceptible to those germs which again could make your condition worse or lengthen the recovery process. It also poses a risk to your fellow gym members as you could be passing on your germs to them.
Personally I hate to miss a workout, but I was recently struck down by a cold with a fever and I didn’t exercise until those fever symptoms went.
I would recommend contacting your doctor if you are concerned, everybody’s situation and physical condition is different. Professional and personal advice is always recommended.