ENDURANCE TRAINING vs IMMUNITY

ENDURANCE TRAINING vs IMMUNITY - What every triathlete should know. As a triathlete, you already know the demands that endurance training places on your body. Balancing swimming, cycling, and running often requires hours of rigorous training sessions. While these efforts build cardiovascular fitness, muscular strength, and mental resilience, the relationship between exercise and your immune system is more complex. Scientific research suggests that moderate exercise lasting up to one hour can boost immune function, but prolonged sessions exceeding two hours may compromise it. This article dives into the nuances of exercise and immunity for triathletes, exploring the role of neutrophils, the risks of overtraining, and how carbohydrates can help safeguard your immune system during prolonged efforts.

Training for a triathlon puts unique stress on your immune system. While moderate exercise enhances immune surveillance (Immune system’s ability to search for pathogens and other nasty’s) and improves your body’s ability to fight off infections, long duration or high intensity workouts can temporarily suppress your immune defences. Striking the right balance between training intensity, duration, and recovery is key for staying healthy throughout the season.

During moderate exercise, your body mobilizes immune cells, including neutrophils, natural killer (NK) cells, and T-cells, which circulate more effectively to detect and eliminate pathogens. Neutrophils, in particular, are critical for immune defence, as they engulf and destroy harmful bacteria and debris through a process called phagocytosis. For triathletes, these temporary immune benefits can help reduce the risk of infections and support overall health.

However, prolonged, or intense workouts lasting more than two hours can create immune suppression, leaving you more vulnerable to upper respiratory tract infections (URTIs) and other illnesses.

Triathletes often engage in training sessions that extend well beyond the optimal one-hour window for immune enhancement. When training surpasses two hours, the body experiences a cascade of physiological changes that can suppress immune function.

Prolonged exercise triggers the release of stress hormones like cortisol and adrenaline. Elevated cortisol levels suppress neutrophil activity and lymphocyte proliferation, impairing the body’s ability to fight infections. During prolonged efforts, immune cells are redistributed to peripheral tissues, such as muscles, where they support recovery. This redistribution leaves fewer immune cells in circulation, temporarily reducing immune surveillance. Endurance exercise generates reactive oxygen species (ROS), which can cause oxidative damage to immune cells if not adequately counteracted by antioxidants. Long sessions elevate inflammatory cytokines like interleukin-6 (IL-6) and tumour necrosis factor-alpha (TNF), potentially overwhelming the immune systems regulatory mechanisms.

These factors can result in a temporary drop in immune function during the post-exercise recovery period, particularly if adequate rest and nutrition are not prioritised. For triathletes, proper nutrition is essential not only for performance but also for immune health. Carbohydrates play a pivotal role in mitigating the immune-suppressing effects of prolonged exercise. Consuming carbohydrates during exercise helps maintain blood glucose levels, reducing the need for cortisol to mobilise energy. Lower cortisol levels translate to less immune suppression. Research shows that carbohydrate intake during exercise can preserve neutrophil activity, helping these cells to continue their pathogen fighting roles even during prolonged efforts. Carbohydrates help stabilise inflammatory responses by attenuating the release of IL-6 and other cytokines during exercise. To protect your immune system during training, aim to consume a minimum of 60 grams of carbohydrates per hour during sessions lasting longer than one hour. This can come from sports drinks, energy gels, or natural options like bananas or dates.

To ensure your training supports both performance and immunity, triathletes should adopt a holistic approach to their regimen. Whenever possible, keep your sessions under two hours, particularly during base-building periods. If longer sessions are necessary, structure them with breaks and incorporate carbohydrates throughout. Rest is as critical as training for triathletes. Schedule regular recovery days and prioritise sleep, as inadequate recovery can prolong immune suppression. Ensure you fuel adequately before, during, and after training sessions. Consuming protein and carbohydrates post-workout will help to replenish glycogen stores and supports immune recovery. Include antioxidant rich foods in your diet, such as berries, spinach, and nuts, to counteract oxidative stress caused by endurance training. Pay attention to signs of overtraining, including persistent fatigue, increased susceptibility to illness, and performance plateaus. Adjust your training load as needed to maintain balance. Proper hydration supports immune function by promoting lymphatic circulation and cellular health. Dehydration exacerbates stress on the immune system during prolonged exercise.

As a triathlete, maintaining a strong immune system is critical to ensuring consistent training and peak performance on race day. While moderate exercise up to one hour enhances immune function, prolonged sessions beyond two hours can suppress it, leaving you vulnerable to illness. By incorporating carbohydrates into your fuelling strategy, balancing training intensity and duration, and prioritising recovery, you can minimise the risks of immune suppression and stay healthy throughout your training cycle. With these strategies in place, you will be better equipped to tackle the demands of triathlon training while protecting your immune system.