Diet, your immune system and the J-curve

Kate Percy is one of our experts in the Run Mummy Run Community Run Club in association with ASICSThese blogs are exclusive to RMR CRC members for a few months before being made public, so if you do want to get expert advice on your running, as well as a training sessions, expert Q&As, access to exclusive kit and much more, join the club today! In this post, Kate gives us some really important advice on how to balance our running and training without overdoing it and compromising our immune systems. She shares her top tips around getting adequate rest and eating good nutritious foods. 

There’s no doubt that running is good for our health. Do the right amount and it can improve your immune system and lower your risk of infection. But is there a risk of compromising this by overdoing it?

Suddenly we’re into winter time! Not only do we have Covid to cope with, but now we’re all out seeing each other again having been stuck in our little bubbles for so long we’re even more susceptible to all the bugs and viruses out there. The colds, the flu, the sick bugs we seemed to have been protected from last year. This got me thinking about the immune system and how we can give it a helping hand by eating well and not overtraining.

The J-shaped curve

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.  There’s a fine line between a good amount of exercise and going over the top! If you’re someone who commonly performs very high volumes and intensities of exercise, and perhaps is at risk of overtraining, your immune system can become even 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.

Top tips for finding your balance

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

1. Nutrition

Quantity: 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. Running takes a lot out of you, so you need to ensure you’re eating enough energy. A deficit in calories or carbohydrates can increase your stress hormones which is detrimental to immune health.

Quality: Think about the quality of your diet. How much processed foods are you eating each week? How much fruit and veg, eggs, wholegrains? 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.

Balance and variety:  Your body needs balance, so think about the balance of carbs, protein and fats on your plate and don’t play about with cutting one particular food group. Most foods consist of a complex combination of nutrients, so the more variety you eat, the better variety of nutrients you’ll get. Ideally around one third of your diet should come from foods rich in slow-release, unrefined

foods which are rich in carbohydrate, such as wholegrain bread, wholewheat pasta, wholewheat cereal, oats and brown rice, around one third from fruit and vegetables, and the rest from foods rich in protein, such as beans, pulses, fish, eggs and meat and fat.

Timing: Listen to your body. Hunger pangs an hour after a run probably mean your body is crying out for you to replenish glycogen stores, so eat when you are hungry to maintain your energy levels and keep your muscles healthy. Don’t grab just anything though because you feel you deserve it; choose nutritious, fresh, natural snacks.

Immune-friendly post-run snacks

    • Boiled egg and wholemeal soldiers
    • Wholegrain toast and nut butter
    • Yoghurt and fruit
    • Banana pancakes
    • Ham and cheese pancake (try my new delicious savoury pancake mix!)
    • Apple, handful of dried fruit and peanut butter
    • Baked potato and baked beans or tuna
    • Bowl of homemade soup and a hunk of bread – try my Feelgood Pumpkin Soup!
    • Kate Percy’s Go Bites (the hazelnut + cacao ones are great for recovery as they contain rice protein)

Of course, with our busy lifestyles processed foods are virtually impossible to avoid, and that’s fine in moderation, but when you do eat them, check the label for hidden sugars and salt.

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. Support that with a day of eating really well to top up your energy levels (ie don’t spend your recovery days not eating because you’re not running and not as hungry).

Stretching on these days is a great idea too! Which brings me onto my last point…

3. Yoga or Pilates!

I’m a fan since lockdown! 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.

About Kate

Hello everyone! It’s a great privilege to have been invited by Run Mummy Run to inspire you with all things food and nutrition! In everything I do, whether it’s my food products, cookbooks or educational resources, my mission is to help you discover what I call #enerjoy through what you eat; that’s great taste, good energy, vitality and happiness. I hope you enjoy my tips and recipes over the coming year. And I hope they bring you #enerjoy!

For more information on Kate Percy’s cookbookshealthy snack products (Kate Percy’s Go Bites) and free nutrition resources, check out or join @katepercys on Instagram, Twitter or Facebook.

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