Bangor University Study Shows Stress Before Marathon Increases Illness Risk

How Stress and Anxiety Affect Runners’ Immunity

Marathon training is often framed around physical conditioning and nutrition, but the latest research from Bangor University highlights a less visible factor that can tip the balance – mental stress. A study involving 406 runners measured their stress, anxiety and mood levels in the weeks leading up to a race and collected saliva samples before and after the run. The results point to a clear link: runners who reported higher anxiety and negative mood states experienced a reduction in mucosal immunity, the first line of defense against respiratory pathogens. Those same runners were more likely to develop cold‑like symptoms within two weeks after the marathon.

What the Science Says

Two experiments underpin the finding. In the first, participants completed validated psychological questionnaires and provided saliva samples. Immune markers such as immunoglobulin A – a key protein that keeps viruses out of the upper respiratory tract – dropped significantly in individuals with elevated stress scores. In the second study, 45 adults were placed on a treadmill for an hour while their pre‑ and post‑run saliva was analyzed. Again, those with higher reported anxiety had a 30% greater decline in mucosal immunity compared to their lower‑anxiety counterparts. The study noted a less definitive effect in women, suggesting hormonal cycles and other variables might modulate the response.

The underlying mechanism involves the hypothalamic‑pituitary‑adrenal (HPA) axis and the sympathetic nervous system, both of which mediate the body’s response to stress. When these systems fire repeatedly – from intense training on top of psychological tension – they can dampen immune activity, creating a window of vulnerability to infection.

Integrating Stress Management into Marathon Prep

Running a marathon underprepared stress can create a hostile environment for the body. However, the evidence also reinforces a broader truth: routine physical activity still lowers the risk of serious diseases, including seasonal flu, even when brief bouts of stress are present. The key is to mitigate mental strain before, during, and after each training session.

Pre‑Race Strategies

• Plan Logistically: Map out travel routes, registration steps, and race day equipment in advance. Set aside extra time for unexpected delays to avoid last‑minute scrambling.
• Night‑Before Check‑Ins: Arrive at the start location a day earlier if possible. Familiarising yourself with the course reduces uncertainty during the actual run.
• Set “If‑Then” Scenarios: Identify potential hurdles (e.g., heat, equipment failure, a surge of runners) and decide beforehand how you’ll react.
• Practice Relaxation Techniques: Integrate diaphragmatic breathing, progressive muscle relaxation, or brief mindfulness sessions into daily splits. Studies confirm these methods lower heart rate and cortisol levels, easing the mental load before a big race.

Training‑Day Tactics

• Warm‑Up Gradually: Start with a light jog and dynamic stretches. A steady transition into the main effort — rather than an abrupt surge — helps control adrenaline spikes.
• Hydration and Fuel: Maintain fluid intake and consume easily digestible carbohydrates in the hour leading up to the start. Solid nutrition stabilises blood sugar and keeps nervous energy from translating into mental agitation.
• Restorative Practices: Post‑race, allow yourself a cooldown comprising slow walking, stretching, and a short seated meditation. These actions signal the nervous system to enter recovery mode quickly.

Post‑Race Recovery

After crossing the finish line, the body still navigates a five‑ to seven‑day window when immunity is suppressed. Follow these best‑practice guidelines:

• Get at least seven hours of sleep each night. Adequate rest restores immune balances and supports hormonal regulation.
• Adopt a diet rich in fruits, vegetables, lean protein and healthy fats; micronutrients such as zinc and vitamin C strengthen mucosal barriers.
• Implement a light recovery week every second or third training cycle. Restorative runs or cross‑training reduce cumulative physiological stress.
• Avoid training until the body resolves any lingering soreness or injury.

Key Takeaways for Runners and Coaches

1. Elevated pre‑race anxiety and mood disturbances predict a higher risk of post‑marathon respiratory illness.
2. Both psychological and physical stressors share common pathways that can suppress immune function; mitigating one can strengthen the other.
3. Standard training benefits largely outweigh the short‑term rise in emotional tension, but strategic stress management is essential for optimal performance and recovery.
4. Practical measures — planning, rest, nutrition, and relaxation — can reduce the influence of mental stress on immune markers.

By acknowledging the psychological component of marathon training, athletes can better design programs that protect their health, preserve performance, and reduce the likelihood of falling ill after a race.

Next Steps for Marathoners

If you’re preparing for your next big race, consider integrating a stress‑screening questionnaire into your training log. Track mood and anxiety scores weekly and use the data to tweak pacing, rest days, or relaxation practice. In doing so, you’ll not only protect your immune system but also gain deeper insight into how your mind and body respond to the demands of long‑distance running.

Want to evaluate how well your training plan aligns with stress‑management principles? Schedule a free training assessment today and receive a personalized action plan that balances intensity with recovery.

Curious about how these findings could shape your future training? Explore our advanced marathon coaching program and get expert guidance tailored to your goals.

Have additional questions or need support during your preparation? Write to our athletic department and we’ll connect you with a specialist.

By staying proactive about mental wellness, you’ll finish stronger, stay healthier and enjoy the full benefits of marathon training.