The confinement situation we are currently leaving behind, as it has been reported by multiple media sources, supposed a threat to the immune system. The lack of contact with the outdoors and hours of sunlight, a deficit of fresh food, an inevitably sedentary lifestyle, in addition to possible sleeping problems, states of anxiety and depression, are direct causes leading to lowering the immune system.
The immune system is a complex set of relationships and interconnections, especially between the hormonal systems and the nervous system. Its optimal operation responds to balance and harmony. Achieving that balance depends on very relative and variable principles. Professional athletes face a paradoxical situation on this subject. Physical exercise activates immunity. Variables known so far are that exercise increases white blood cells, short, intense exercise increases lymphocytes, and prolonged exercise increases neutrophils. Nevertheless, in high competition, moments and situations of high cortisol levels and phases of immunosuppression can take place.
After highly intense training or exhausting exercises, a decrease in immunity of up to 24 hours is common. They are transitory changes, returning to normal afterwards, but they make up what is referred to as an “open window” of opportunity for infections of all kinds. Infections in the respiratory tract in high-performance stages are frequent. Moreover, an increase in intestinal permeability due to great physical effort can allow the entry of bacterial endotoxins into the blood circulation.
In order to prevent the weakening of the immune system, athletes are recommended to control the training load and progressively increase their intensity to no more than 5 or 10% weekly. It is preferable to perform more regular shorter training sessions than fewer, but longer sessions. The intense and prolonged effort is the one that has the most effect. Furthermore, during exercise, physiological changes such as the increase of body temperature and the decrease of oxygen saturation can also affect immunity.
It is also important to always implement recovery workouts immediately after the hardest sessions, and it is advisable to introduce recovery weeks every two or three intensive ones. Likewise, it is essential to stay hydrated during training. This is important because it helps to keep the flow of saliva, in which proteins with antimicrobial properties are found. It is also necessary to take carbohydrates after exhaustion in order to regulate cortisol, a temporary immunosuppressive factor. If after the session urine is dark, it means that more water must be replaced due to the weight lost during exercise. At least, until its colour is lighter.
Emotional and stress factors are also closely linked to immune system changes. However, stress can only be measured as the level of anxiety that a person suffers according to their own perception, this is due to the causes that produce stress do not affect everyone equally. There are those who do not get upset in the face of great adversity and, at the same time, others who can feel unsettled due to a small detail that they feel is beyond their control.
Additionally, physical stress, combined with a lack of sleep and other kinds of disadvantages, can give the feeling that the athlete does not control the situation. The feeling of lack of control is the stress factor. In this aspect, it is normal for all kinds of stress that the athlete may suffer (both psychosocial and physical) to be monitored and to have control over their state of mind to help by enabling anxiety control tools if necessary.
In elite sports, long-distance travel and high-competition stress and anxiety cause the “open window” phenomenon to be longer and more frequent. In the face of this risk, the emotional response was given to the different situations of mental exhaustion and stress that an athlete encounters influences the neuroendocrine response.
Traditionally, attempts have been made to recommend athletes an environment in which they can avoid any unnecessary life stress. Many athletes train in situations of complete isolation. Nevertheless, it is impossible to establish scales and catalogues on the social and emotional concerns for athletes who have different origins, cultural and socio-economic backgrounds. It is ideal to provide the athletes’ tools so that they can learn to manage stress and come out strengthened and adapted to the highest physical and mental demand.
Sleeping problems are also common in the elite. Research has found that they have worse sleep patterns than non-athletes. It has been shown that sleeping less than seven hours a day decreases the antibody response. The possibilities of contracting a rhinovirus, the most common human pathogens and those responsible for the common cold, are four to five times higher without regular sleep.
The most frequent recommendations for athletes are to establish sleeping routines. Always sleep more than seven hours on a regular basis; not sleeping less one day and trying to make up for the hours the next day. Lost sleep can’t be compensated. However, naps or periods of sleep of no more than 30 or 45 minutes can indeed be beneficial. Of course, it is essential to ensure good darkness in the room and, once in bed, stay away from screens.
The most complex field is that of nutrition. Traditionally, it is known that foods rich in Vitamin C, Vitamin D and zinc are the ones that strengthen the immune system the most, and probiotics tend to be recommended for athletes who make continuous journeys, but the administration of a standard diet is not possible. It always depends on many factors related to the professional’s profile and their sports discipline.
Broadly speaking, the margins with which nutritionists work are based on striking a balance between energy intake and expenditure and avoiding extreme diets. Good nutritional quality is achieved with high contributions of phytonutrients that ensure healthy levels of micronutrients. Then, depending on each professional’s particular situation, nutritionists assess whether the incorporation of supplements is necessary to strengthen the immune system. Many times, as a precaution, depending on their schedule, for example.
A normal and healthy diet would include having fish a minimum of four times a week, two of them oily fish, and caloric intake with a fat content of 25-35%, depending on the athlete’s goals and their kind of training. If the most common disease behind the “open window” of immunity after tough training is treated, quercetin, for example, found in apples and onions, reduces upper respiratory tract infections.
During this current situation, the athlete’s biggest concern is to find themselves in a state of detraining. When a reduction in physical activity is produced, whether due to an illness, an injury, or holidays, which affects the athlete’s anatomical and physiological adaptation, it leads to cardiorespiratory, muscular, and metabolic changes. If the interruption is more than four weeks long, it is considered long-term detraining. With only a few days of detraining, it has already been detected that plasma and blood volume, as well as hormonal changes, can be reduced.
Nowadays, sports immunology is a subject of sports science. It is not scientifically clear yet why prolonged exhausting exertion can alter the immune system. The most recent studies show that there may not be a destruction of immune cells, but a concentration of them in sensitive places, for instance, during exercise, the lungs area. What is indeed certain is that the benefits of physical exercise for the body outweigh any negative effects it may have.
Recommendations to maintain immune health in athletes – European Journal of Sport Science
Exercise, training, and the immune system – Sport Medicine, Training and Rehabilitation
Nutritional strategies to counter stress to the immune system in athletes, with special reference to football – Journal of Sport Sciences
Immune function and exercise – European Journal of Sport Science
Debunking the Myth of Exercise-Induced Immune Suppression: Redefining the Impact of Exercise on Immunological Health Across the Lifespan – Frontiers in immunology
How to reboost your immune system – Harvard Health Publishing
The immune system in sport: getting the balance right– British Journal of Sports Medicine
Cambios fisiológicos debidos al desentrenamiento – Apunts. Medicina de l’Esport