Weeks, sometimes months of training are behind you. Your season highlight is within reach, and then your throat starts to feel scratchy. Right now? We explain what this means for your planned race.
Why right before your season goal?
It feels like bad luck: just when you scale back your training to be ready for the race, you get sick. In fact, it’s not just chance, because besides bad luck there’s also an explanation for the increased risk of illness.
Every long, intense training session weakens the body’s mucosal defences for a few hours up to a few days, for example because the concentration of antibodies in saliva drops and certain immune cells temporarily work less effectively. If this happens during an intense training phase, where one hard session follows the next, this weakened phase often persists before it can fully recover, and the drop in immune defence adds up over time. This is known as the open window phenomenon.
The pre-race phase is particularly vulnerable because it’s often preceded by the most intense training weeks. The cumulative deficit from the open window phenomenon is therefore relatively large at the start of the taper phase, and it takes a few days for the open window to close again.
Train or take a complete break?
The most important decision-making aid comes from sports medicine and is as simple as it is memorable: the so-called neck check, originally described by sports physician Randy Eichner and since adopted by major sports medicine associations.
Symptoms above the neck, such as a runny nose, a slightly scratchy throat or sneezing, generally don’t rule out careful, moderate training.
Symptoms below the neck, such as a productive cough, tightness in the chest, fever, aching limbs or gastrointestinal complaints, are a clear stop signal. In this case, the rule is: take a break, no matter how little training is actually left.
This simple distinction doesn’t replace an individual medical assessment, but it gives you initial guidance when you’re unsure.
How much fitness does a cold cost me?
This is often where the biggest worry comes in: “If I don’t train, I’ll lose all my preparation.” Research paints a more nuanced picture than is often assumed.
In the first week of a complete training break, endurance performance is largely maintained. Only after about two weeks do several studies show a slight, measurable decline in VO₂max (4 to 5%). For the few taper sessions you miss because of a cold, this means: the first few days hardly cost any noticeable race fitness, but this would change with a longer, forced break lasting several weeks.
That leaves the question of when it makes sense to get back into training. Sports medicine guidelines state that you should have at least three consecutive symptom-free days before resuming training. An additional warning sign is an elevated resting temperature (plus 0.5 to 1 degree) or an elevated resting heart rate (plus 10 beats per minute), even without noticeable fever. And even once you’re symptom-free, your performance usually isn’t fully back yet; this usually takes an additional 2 to 4 days. Realistically, this means: wait three days, then allow for a few more days with noticeably reduced fitness, and only after that will you be back at your usual level.
When is caution really needed?
As relaxed as you can be about an ordinary cold, there’s one thing that leaves no room for manoeuvre: fever.
With a febrile infection, the risk of inflammation of the heart muscle (myocarditis) increases under intense physical exertion. That’s why sports medicine associations recommend strict, complete rest in case of fever until it subsides, combined with caution in the first days of illness even without noticeable fever, as some infections only show up with a delay. If symptoms persist or are unclear, getting a medical check-up is always the safest option.
Conclusion
A cold shortly before your season highlight is more common than you might think. With the neck check as a basis for your decision, the knowledge of how little a short break actually costs, and a clear red line when it comes to fever, you can assess the situation calmly and in an informed way, instead of deciding on gut feeling.
This article does not replace medical advice. If you have persistent, severe or unclear symptoms, especially fever, chest pain or shortness of breath, please see a doctor before you continue training or start a race.
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