The J Curve - the relationship between exercise and your immune system

Want to keep your immune system as strong as possible?

Are you highly active? Watch out for the J CURVE! 

Here registered nutritionist Sophie Heath tells us why we shouldn't overdo our workouts! 

There is no doubt that exercise is good for our health: Do the right amount of and it can improve your immune system and risk of infection. But is there a risk of compromising this by too much exercise?

I try to maintain a good balance in my life, ensuring I have a full recovery day once a week, and do lower intensity forms of activity like yoga a couple of times per week. But this winter I’ve been particularly susceptible to the common cold and it’s got me thinking about something I learned when studying nutrition and sports science at University – the J-shaped curve. It might be that the reason I’ve not been able to shift a cold quite so quickly is because I have been over-training:  I’ve got over-excited, taken my training too far and it’s effected my immune system.

The J shaped curve (as shown in the image) plots the relationship between exercise and immunity moving from sedentary to excessive exercisers. It’s a culmination of multiple observations and studies that have determined the link between increased exercise and improved immune function.  But equally, if you are someone who commonly performs very high volumes and intensities of exercise, and perhaps is at risk of overtraining, your immune system can become weaker than if you were sedentary. This increases your risk of picking up infections (URTI stands for Upper Respiratory Tract Infections if you didn’t know!).  Critically, it seems the Kate Percy's mantra of ‘everything in moderation’ is never a truer word spoken when it comes to exercise and keeping fighting fit!

How do you find the right balance and maintain a training intensity that’s good for your health? Here’s my top 3 tips to help reduce the risk of overdoing it:

1. Nutrition – of course! If your training is particularly intense, you need to make sure you aren’t stressing it even more by eating the wrong amount and type of foods. Ensure you are eating enough energy – not having the right amount of calories or carbohydrates can increase your stress hormones which is detrimental to immune health. Secondly the quality of your diet should be top notch – meaning limited processed junk and plenty of fruit and veg. Your 5+-a-day contains so many crucial vitamins, minerals and other compounds that have both antioxidant and anti-inflammatory effects, and are immune boosting too.
2. R&R. I know it’s difficult when you have specific goals in mind, but many of us massively underestimate the importance of recovery time. This doesn’t mean we have to sit on the sofa all day. Why not take one day a week where you focus on a very light session, or even just get outdoors for a walk. Stretching on these days is a great idea too … which brings me onto my last point …
3. Yoga! I’m such a yoga fan. It has so many benefits. I believe it is the perfect way of tuning into your body to see what aches, what feels good, how energised you are etc. This way we get time to listen to our bodies and judge whether we need to tone it down. It is of course great for stretching (helping to reduce the risk of injury) and switching off mentally too (which can help with sleep) – what’s not to love?

So make sure you tune in to your body, get the required rest and fuel it sufficiently and nutritiously to help reduce the risk of getting run down and poorly.

Sophie Heath, Nutritionist