During the winter months, many people catch a cold or flu. For athletes, this can be a dilemma: should you stick to your training plan even when you’re not feeling well? In this article, you'll find out whether it’s wise to train when you have a cold or flu and how to resume your workouts responsibly.
Cold and flu: differences and symptoms
Although people often confuse the flu with a cold, they are different infections with distinct symptoms.
- Cold: Usually a mild infection caused by various viruses. Symptoms include a sore throat, sneezing, a blocked nose, coughing, headaches, fatigue, and sometimes a slight fever.
- Flu: Caused by the influenza virus and often more severe. Symptoms include fever, chills, muscle aches, and a general feeling of illness.
Both conditions usually improve after 5 to 7 days. Full recovery can take 10 to 14 days, although setbacks may occur.
Exercising with flu or fever: not a good idea
If you have flu or fever, exercising is dangerous. A fever means your body is actively fighting an infection. Training can interfere with this process and may even lead to serious complications such as myocarditis (inflammation of the heart muscle).
Advice for flu or fever:
- Rest for at least 1 to 3 days after your symptoms have gone.
- Start with a short, easy workout to test how your body responds.
- If this goes well, gradually resume your normal training schedule.
If you've had flu or fever and start feeling better, your body still needs a few days to fully recover. Resuming training too soon increases the risk of a relapse and prolongs the recovery process, meaning you could miss even more sessions.
Exercising with a cold: the ‘neck check’
If you have a cold, you can use the so-called ‘neck check’ to determine whether it’s safe to train:
- Symptoms above the neck (such as a blocked nose or sore throat without fever): Light training is possible.
- Symptoms below the neck (such as coughing, muscle aches, or fever): Avoid exercise.
Always listen to your body. If you don’t feel well, take a rest day, even if your symptoms are mild. Consult your coach/trainer about adjusting your training plan if necessary.
Why rest is important
It’s not a good idea to resume training too soon after being ill. If you’re not fully recovered, your training effectiveness is low, and you’re at higher risk of overtraining. Additionally, an untreated or lingering cold can impact your performance for weeks. Illness also weakens your immune system, making you more susceptible to new infections. This can create a snowball effect, where you keep getting sick repeatedly.
Tip: Use a sports watch to measure your Heart Rate Variability (HRV). This can give insight into how well you’ve recovered. A low HRV may indicate fatigue or illness. HRV might even help predict a cold, though more scientific research is needed1.
Is it bad to miss a few training sessions?
There’s no need to panic if you miss a few training days. Missing some sessions has little impact on your long-term goals:
- 3-5 days of rest: No significant changes in fitness.
- One week of rest: Slight decline in fitness, but temporary.
- 10 days or more of rest: VO2max starts to decline gradually2.
If you are unable to train for more than 10 days, consult your coach. It may be beneficial to repeat the last 1-2 weeks of your training plan.
Important: Your performance depends mainly on the total number of training days and their quality. If you are ill, it is better to recover fully before resuming training rather than staying fatigued for longer or falling ill again.
Protect yourself from infections: tips for a strong immune system
During the winter months, the risk of infections such as colds, flu, and even coronavirus is higher. It is best to prevent illness where possible, and by making the right choices, you can strengthen your immune system and reduce the risk of getting sick.
Here are some practical tips:
- Wash your hands regularly: Use water and soap, especially after touching public surfaces or being in contact with ill people.
- Avoid crowded places: Try to stay away from large gatherings.
- Limit contact with sick people: Keep your distance from those who are coughing or sneezing and avoid shaking hands.
- Eat healthily: Ensure you eat enough and follow a diet rich in fruit and vegetables to boost your immunity.
- Get enough sleep: Sufficient sleep strengthens your immune system.
- Manage stress: Chronic stress can weaken your immunity, so make time for relaxation.
By incorporating these habits into your daily routine, you not only protect yourself from infections but also improve your overall health and athletic performance.
Conclusion
Exercising while ill, especially with flu or fever, is not a good idea and can even be dangerous. Your body needs rest to recover, and returning to training too soon can slow down your recovery or lead to complications. With a mild cold, you may sometimes continue training cautiously, but only if symptoms remain above the neck and you still feel well.
The most important thing is to listen to your body and adjust your training according to how you feel. A few days of rest has little impact on your long-term goals and can even prevent you from being sidelined for longer. Take the time to recover fully and gradually resume your training. This way, you not only improve your performance but also ensure a sustainable and healthy sporting career.
1. Hellard, P., Guimaraes, F., Avalos, M., Houel, N., Hausswirth, C., & Toussaint, J. F. (2011). Modeling the association between HR variability and illness in elite swimmers. Medicine and science in sports and exercise, 43(6), 1063–1070. https://doi.org/10.1249/MSS.0b013e318204de1c
2. Mujika, I., & Padilla, S. (2001). Cardiorespiratory and metabolic characteristics of detraining in humans. Medicine and science in sports and exercise, 33(3), 413–421. https://doi.org/10.1097/00005768-200103000-00013
