Every athlete and coach makes plans. 

Calendar planning, training block planning, travel planning, race planning – the list goes on.

But, one of the biggest threats to those plans? Sickness.

No one plans on missing whole sessions, days or weeks on the training track because they’re sick.

Unfortunately it happens and in many cases, more often than we’d like it to.

In the event you’re well enough to keep moving and actual sessions or days aren’t lost, training intensity will likely need to be backed off, and planned outcomes abandoned.

Listening to your body is important, so understanding what can be achieved in training when a cold, flu or otherwise takes hold is important – pushing yourself in the face of a depleted immunity will only result in prolonged sickness.

So, what does it mean for you when immunity is compromised during training?

Well, for endurance athletes aiming for high training loads – it’s a pretty simple mathematical equation – fewer sick days means more opportunity to get those base kilometres in. 

This has been documented in the Journal of Sports Science and Medicine(1) with researchers analysing the training diaries of elite endurance athletes – long distance running, cross country skiing and biathlon – for the number of both self-reported and physician-reported illnesses, as well as training sessions lost or modified. 

They concluded that “performance, especially in endurance sports, is incompatible with a high rate of infections”.

While training days lost can have a physical impact on race prep, there’s also an untold psychological impact, knowing you’ve lost chunks of time or missed key sessions can be a real knock to your confidence. 

I can certainly remember as an athlete the disappointment of waking with an undeniably sore throat or stuffy nose during my prep, and on the flip side, the calm confidence of lining up for a race after an uninterrupted, illness free training block. 

Both physical and psychological factors play out in research as we’d expect. 

A study of 33 elite Australian track and field athletes(2) and their training status and results across a 5 year period, showed the likelihood of achieving a performance goal increases 7-times in athletes who managed to complete more than 80% of planned training weeks. Training lost to injury or illness had a direct and negative effect on performance, with every session that had to be modified reducing the chances of success.  

This same principle applies to any level of athlete or active individual – consistency is key – and that measured, consistent plan also avoids the temptation of panic training if you need time off with illness, which can in turn, increase risk of injury or overload. 

So how do we achieve that consistency? Well, there’s lots of elements that come into play.

We know that exercise actually strengthens your immune system, but only to a point.

Very high volumes and intensity of training actually puts stress on your immune system – meaning serious athletes are often more susceptible to picking up colds and sniffles as their body battles to recover from session to session.

You need to ensure that your body is being supplied with all necessary nutrients – a varied diet including fresh fruits and vegetables, lean proteins and wholegrains, while limiting processed and refined foods. 

Manage your energy intake, with both very high and very low intakes compromising your immune system and increasing the risk of infection.

Find a supplement that can adequately support your diet and your body’s requirements when training is high, with micros including vitamin C, vitamin D and zinc the best bet.


  1. https://www.researchgate.net/publication/268985716_High_Training_Volumes_are_Associated_with_a_Low_Number_of_Self-Reported_Sick_Days_in_Elite_Endurance_Athletes
  2. https://www.researchgate.net/publication/291348067_Performance_success_or_failure_is_explained_by_weeks_lost_to_injury_and_illness_in_elite_Australian_Track_and_Field_athletes_a_5-year_prospective_study