Running, Respiratory Infections and VO2 Max

Dedicated runners pride themselves on maintaining high levels of health and fitness. But excessive training can turn the tables on your immune system and lead to upper respiratory infections that diminish your aerobic capacity and compromise your performance. Understanding the relationship between overtraining and your immune defenses can help you train smarter for optimal performance and better health.

  1. Respiration and VO2 Max

    • Respiration is the process of inhaling to bring oxygen into your body and exhaling to rid your body of carbon dioxide. When you exercise, respiration increases in both volume and frequency to meet the oxygen demands in your muscles. The volume of oxygen you consume while running goes up proportionately with your work rate until you reach your VO2 max, the maximum amount of oxygen your body can use during exercise. According to the Centers for Disease Control and Prevention, VO2 max is the best indicator of a person’s cardiorespiratory fitness. While VO2 max is limited by genetics, aerobic training can help you achieve your genetic potential. But overtraining can have negative effects on your respiratory system.

    Immune System and Training

    • Your immune system functions to maintain equilibrium in your body by protecting it from invasive organisms. According to sports specialists at Rice University, your immune system responds to training in ways similar to other physiologic systems in your body. When you strike the right balance of training and rest, your immune system grows stronger and more effective. But overtraining can compromise your immune system and lead to an increased incidence of upper respiratory infections, or URIs.

    URIs and Training Volume and Intensity

    • The volume and intensity of your running program has a direct influence on your immune system's ability to fend off URIs. A 2010 research article by Martin et al. published in "Exercise and Sport Sciences Review" noted that prolonged intense exercise suppresses the immune system, while moderate intensity exercise bolsters your immune response and may reduce the risk and severity of URIs. A 2013 Brazilian study by Telxeira et al., published in "Oral Diseases," found that changes in salivary enzymes boosted resistance to URIs in response to moderate intensity exercise, but other salivary changes increased the risk of URIs 24 hours after a bout of strenuous exercise.

    Overtraining Syndrome

    • Hard training can improve your VO2 max and enhance your performance, provided you allow enough rest time between bouts of running for your body to recover. But an ongoing imbalance between training and rest will lead to a decline in performance, a condition known as overtraining syndrome. Overtraining syndrome is a state of ongoing physical stress to the point where regular rest is no longer adequate to allow an athlete to recover. Symptoms include fatigue, persistent muscle soreness, increased injuries and increased frequency of viral infections. Treatment for overtraining syndrome is a prolonged period of rest lasting from days to weeks, depending on the severity and duration of your symptoms.