Optimizing Immunity for Performance

Last updated: 23-Aug-18

By Renee McGregor

For any individual who is physically active and trains over four times a week, let alone whether they are striving for performance, immune health is something that should not be overlooked. There is a lot of evidence that demonstrates how strenuous exercise, if not managed well through rest, recovery and nutrition can depress the immune system, hindering performance outcomes.

For this reason, the average baseline for immunity is not enough and more attention is required by runners, and particularly ultra runners, to maintain a healthy system.


Good nutritional practices are absolutely necessary for good performance and immune health. While healthy eating guidelines around consuming an increased volume of foods high in anti-oxidants are important, it also pays to think about all food groups. One of the key aspects of sports nutrition is tailoring requirements to training needs; so, as load and intensity increase then nutritional intake will also need to increase for an optimal outcome.

In addition to food intake, hydration plays a critical role in immune health. Hydration should not be ignored as it encourages the production of saliva which contains high levels of IgA; the body’s first line of defence. (Walsh NP, et al.2011).

While this is usually easy to manage during the warmer months, it can be a challenge in the winter when many runners find it more difficult to drink large quantities of water. Herbal tea, no-added-sugar squashes and flavoured waters can all help you drink to maintain hydration around and during training sessions. After exercise, milk-based recovery drinks can help rehydration as well as glycogen restoration and muscle repair. (Gleeson, 2016).

One of the most important things you should consume for good immune health as a runner, is carbohydrate. Ensuring sufficient amounts throughout the day, particularly during high intensity or volume training blocks, encourages appropriate fuelling and recovery for the body, preventing, the suppression of the immune system.

As a recommendation, aim for a third of your plate at every meal to be wholegrain, nutrient-dense carbohydrates such as sweet potato, pasta, rice etc. on training days, and a quarter plate on non-training days. In addition, leading into higher intensity and longer endurance days, take on more carb-based snacks, also during endurance training sessions that are over 90 minutes. You should aim for 30-60g of carbs an hour.

An added bonus is that these whole grains, along with beans and pulses, are prebiotics, nutrients necessary for the correct action of probiotics to encourage a positive environment for gut flora to thrive, helping to boost immune health.

While you can obtain most of the nutrition you need through your diet, there are two supplements that are worth considering, especially during the winter months and in the lead up to major races: Vitamin D and Probiotics.

Vitamin D

One of the main challenges, especially for UK-based athletes due to the limited/lack of sunshine, is to ensure you get enough Vitamin D, therefore regular monitoring is advised. Vitamin D is a very important nutrient when it comes to immune function and mood. Luckily it is very easy to supplement through the winter months.

For individuals who are highly active, a serum Vitamin D level of above 75 is recommended, anything under this should be supplemented (see monitoring below). If levels are below 50 then aim for 4000 iu a day; if levels are 50-75 then aim for 1000 iu a day (He et al, 2013; He et al, 2016).


Numerous studies have demonstrated that a 12-week course of high-strength probiotics can prevent the incidence, and reduce the severity, of upper respiratory tract infections in athletes in the lead up to, and after, a major competition (Gleeson & Thomas 2008, Cox et al 2010; Gleeson et al 2011; West et al 2011, 2014). One of the most critical times to boost your immune health is in the two weeks immediately after a race as this is when your immune system is significantly depressed.


While managing training and nutrition are critical for a healthy immune system, there are key lifestyle behaviours that can also have a big impact. It is absolutely crucial to obtain sufficient sleep each night, ideally around 8 hours. The Growth Hormone, responsible for physical repair is at its highest around 12-2am. Aiming to get to bed early enough, will ensure that you make the most of this.

To minimise sleep disruption, aim to turn off laptops and phones at least 30 minutes before your preferred sleep time, as the blue light interferes with melatonin production – a key hormone required for quality sleep (Peake JM, et al. 2017).


The best way to keep on top of your immune health is to track and monitor. Regularly monitoring the levels of Iron, Ferritin and B12, thyroid function, Vitamin D, WCC and CPK, in the blood is important to understand how the immune system is functioning, especially during high volume and/or intense training blocks.

With this knowledge, strategies can be implemented to ensure the best possible health for each athlete. Ideally, I would recommend testing at least 3-4 times a year and always after a heavy training load phase and prior to a return to training.

About the writerRenee Mcgregor is a Sports Nutritionist and Author who has worked with Paralympics GB and many GB endurance athletes.

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Global - Virtual


A virtual race which can be run at any time shown on the dates shown, on any type of terrain in any country.

Suitable for

For runners from beginners to experienced as you choose your own course and challenge based on the guidelines and options set by the virtual race organiser.

Endurance - Multi-activity


An ultra distance race including at least two of the following activities such as running, swimming, cycling, kayaking, skiing and climbing. It may also include different climatic conditions (eg ice, snow, humidity, cold water, mud or heat).

Suitable for

Experienced multi-skilled athletes who have trained for the different activities included in this event. Admission to these races may be subject to receipt of a recent medical examination certificate. Check with the race organiser regarding entry requirements and any specialist equipment required such as a wetsuit, skis or a mountain bike.



Increase of up to 2000 metres with very challenging climatic conditions (e.g. ice, snow, humidity, heat or at high altitude)

Suitable for

Very experienced long distance ultra runners (min 3 years’ experience) or are doing regular long distance running (>50 miles) with elevation and conditions shown (where possible). Admission to these races is often subject to receipt of a recent medical examination certificate. Purchase of specialist kit is often recommended for these races.



Increase of up to 2000 metres with some challenging climatic conditions (e.g. ice, snow, humidity or heat)

Suitable for

Experienced runners who have completed at least 4 ultras in last 12 months, or are doing regular long distance running (>50 miles) with elevation and conditions shown (where possible). Admission to these races may be subject to receipt of a recent medical examination certificate. Check with the race organiser regarding entry requirements.



Increase of up to 1500 metres

Suitable for

Runners who have completed several ultra distances or similar events, or are doing long distance running regularly, with elevation shown.



Increase of up to 1000 metres

Suitable for

Runners who have completed at least one ultra in last 6 months or are doing long distance running (>26 miles) regularly, with elevation shown.



Very little change < 500 metres

Suitable for

First ultra event. Runners completing a marathon or doing regular long distance running (>26 miles) in the last 6 months.