Why do you get sick after working out?

And should you exercise when you’re run down?

If your exercise efforts are being frustrated by poor immunity, this post is for you.

In 1999, I rode a motorbike across Australia with my then-boyfriend, from Perth to Cairns through the desert on dirt roads.

As a personal trainer, I knew that being in top physical shape would mean a better trip. So I trained hard in the gym for eight weeks, gained about 2kg of muscle and was feeling amazing in the lead up to the trip.

About 9 days before we were due to leave on our 6-week adventure, BAM!

I got the flu. And I mean THE FLU. I was bed-ridden.

We went on the trip anyway, and I was physically pushing myself on the ride every day. I was sick for about 8 weeks – the whole trip, and then some.

Even now, if I step up my exercise, I will get a minor cold or an infection of some sort within a few days, about 70% of the time.

Let’s look at why this happens, how exercise relates to immunity, and how you can lower your risk of getting sick.

Stress and Your Immune System

If you get sick after working out, it basically boils down to the fact that you’ve put too much stress on an already-stressed body, which lowers your immunity.

In other words, exercise itself is not the main problem – pre-existing stress is the REAL problem.

Any of the following stressors can be enough to push your body into a hyper-stressed state (“fight or flight” mode).

  • you’re recovering from burnout
  • you’ve just been through a major life stress
  • you’ve have a busy few weeks at work and running on adrenaline
  • it’s an emotional time in your life
  • you have a weak digestive system
  • you have a sluggish liver
  • you’re not sleeping well
  • you’re not eating enough vegetables, or regular meals
  • you’re on multiple medications
  • you’re exposed to environmental or dietary toxins
  • you drink alcohol regularly
  • you’re constantly on edge, anxious or wired up.

How many of these are relevant for you? Just one is a big enough challenge for your body, and exercise (especially intense exercise) can be the final straw.


Oh, and there’s one more pre-existing stressor – you’re over the age of 35. Read more about that, here.

Your Body Type and Immunity 

It’s worth mentioning that certain body types are more prone to immune system issues than others.


  • Most ectomorphs, who are generally introverted, easily overwhelmed anxious types
  • Mesomorphs who are out of balance, driving themselves too hard and/or partying too hard, or
  • Entomorphs who are out of balance because they’re putting everyone first, are anxious due to overthinking things.

In any of these situations, raised stress hormones are a problem.

Do You Get Sick After Working Out? Here’s What You Can Do.

Stress puts your body into ‘fight or flight’ mode, and this increases wear and tear on your body.

That means your best solution is to do things to reduce stress, counteract that wear and tear, and get adequate rest and recovery.

Here are some things you can do.

At times of high stress:

  • Back off the intensity, duration and frequency of exercise. Try walking in nature, light weights or gentle yoga instead.  
  • Prioritise good sleep – a wind-down ritual, right temperature, bed before 10pm. 
  • Eat regular meals with plenty of green vegetables and herbs, and a little lean protein and healthy fat at EVERY meal.
  • Make sure you’re well hydrated all day, every day.
  • Switch off devices by sunset. The blue light in those screens pushes up stress hormones.
  • Take a high quality vitamin and mineral supplement to counteract the oxidative damage caused by stress. Make sure it contains adequate zinc and vitamin C in highly absorbable forms.

Other things you can do:

  • Maintain a constant body temperature. Avoid getting too hot (summer) or too cold (winter).
  • Reduce alcohol intake. It’s a metabolic poison that breaks down into a toxin called acetaldehyde.
  • Slow down on the stimulants. Coffee and chocolate push up your stress hormones.
  • Boost digestion if it’s a problem for you, using probiotics, apple cider vinegar (if tolerated) and digestive enzymes. 



If you are sick with a cold or flu, or an inflammatory condition (raised glands, hives etc), it’s also a sign that your body needs a break.

If you want to recover from illness quicker, then it’s best to reduce or stop exercise for a few days. Research indicates that exercising when you’re sick may prolong the duration of illness – and who wants that?

Some slow, pleasurable walking is probably all you need. 

What To Do When You’re Less Stressed

Life isn’t always stressful and there are times you’ll feel really good, strong and healthy. You might not get sick after working out EVERY time….just when you’re run down or stressed.

The lesson is that even when things feel good, it’s helpful to keep the stressors at bay with some daily rituals that will prevent you from getting sick. These might be:

  • A relaxing wind-down ritual at night
  • Eating plenty of vegetables with lean protein
  • Using meditation, yoga or journaling to lower stress and anxiety
  • Finding time for fun, creativity and flow to boost your resilience

A Final Word

Do you get sick after working out? The simplest and most powerful thing you can do is to listen to your body and pay attention to your needs.

Adjust the amount of rest, sleep and recovery you get each day according to what your body is telling you.

Feeling tension in your muscles? Maybe you need a massage or bath.

Feeling anxious? Take time out to unwind and have fun.

Feeling tired? Take a rest or a walk in the fresh air, and have an early night.

If you keep an eye out for early warning signs of either excess stress or impending illness, you can put your recovery strategy into place as soon as possible and stay healthy and well, no matter what’s going on in your life.

I’d love to know what works for you – let me know in the comments below.

Melanie White

Melanie White

Chief Inspiration Coach

I'm a quirky scientist and a Health and Wellness Coach who helps 35+ women to understand and eat right for their body type.