One of the most frustrating things for an endurance athlete is getting sick. You have a training plan. You're good to go. Your body fails you.
Sometimes you can train right through it, and you actually feel better. Sometimes, training is just going to make you feel worse. So, how do you know which is which?
I'm no expert, but I'm going to list some of the things I consider when I'm sick.
1. Is it above or below the neck?
This is one of the most common rules you'll see quoted when talking about training through illness. If it is just a head cold, chances are you're okay to train. In my experience, sometimes training makes me feel better. It's like it clears out the sinuses. If it's in your chest, you have to consider it a bit more. Just post nasal drip? I'm often still okay. A deeper cough or chest thing? Not necessarily.
2. How's your energy?
Now, when I'm sick, my energy is at least somewhat sapped. This is where I try to consider whether I actually have no energy or just feel like I have no energy. In the last week, most days, I've been wiped out by walking across the room. That's a good sign that I don't have a run in me. On the flipside, sometimes it's when I start getting active that I feel better. If you're really not sure, one test is to just give it a shot. In my experience, I usually start feeling good about 5 minutes in. Or I feel like I'm going to die when I've barely started.
3. Can you keep down food?
Food is fuel. In order to train you have to take in fuel. If your stomach is treating you in such a way that you can't eat or can't keep it down, you can't train. Period.
4. Do you have a fever?
If you have a temperature, it probably means your body is fighting an infection of some type off. The temperature itself isn't the primary indicator, but if it's there, you likely don't have much training in you anyways.
Whether it's right to train while sick is an entirely subjective thing. You have to listen to your body, the same as you do when you get that niggle in your knee or your ankle starts twinging. If you do decide to train through, it might be wise to adjust the intensity. I'd lie if I didn't admit that where I am in my training plan has an effect as well. If I was peaking for my half ironman race right now, I might have fought through this and trained anyways (and possibly paid the price by staying sick for longer).
So, what about you? How do you decide whether to train while sick?