The convincing theory that hard training reduces immunity to disease and thus has a negative impact on performance was challenged in an Australian study of male and female professional floats. It became clear that one training season did not increase the concentration of immunoglobulin in saliva and, moreover, that respiratory tract infection had no notable impact on competition performance.
It has been proven in previous studies that the training of highly trained athletes causes changes in the immunity of the mucous membranes. In particular, by lowering the secretory immunoglobulin IgA and IgM. The researchers involved in this study were interested in supporting these earlier findings. Their concern was not to find out if these changes led to parallel changes in the incidence of disease, or if these diseases in turn had any impact on competitive performance. A guess that has not yet been experimentally verified.
The study looked at members of the 1998 National Swimming National Team during their four-month preparation for the Commonwealth Games (CG) held in Kuala Lumpur, Malaisen that same year. The crew consisted of 41 swimmers aged 15-27 years; they were observed between May and August, while a control group of 25 coaches and other employees were subjected to the same conditions, of course without training.
At the beginning of the study, one week after the National Swimming Championships in Melbourne, all team members delivered saliva samples for immunoassay. After 15 weeks of training, they were retested 17 days before the start of the games. Episodes of respiratory illnesses and infections were identified and recorded by the team physicians during the 6-week recovery period before and during the CG swimming competitions. The competition performance of the swimmers in the national title fights (May) and the CG (September) was measured and compared with regard to the disease history and the immune status, which was evident by the concentration of immunoglobulins.
In the CG, the Australian team has won a total of 48 medals (24xGold) and was thus the leading nation of swimming competitions in the CG. Compared to the national championships, where they reached 945 points, they scored in the CG 947 international points.
The incidence of individual disease episodes during the recovery and competition period of the CG was considerable. Overall, 42% of the participants were affected, but the symptoms were mostly mild. Only three swimmers were ultimately ill during the competition week and all were healthy enough to compete in their respective competitions.
Despite intensive training by the swimmers between May and August, there were no significant changes in the concentration of IgA and IgG in saliva. Only small differences of IgM in saliva were noted, but this was not consistent with previous studies. In addition, there were no clear differences in immune markers between healthy and sick swimmers. However, the same comparison of sick and healthy coaches and co-workers showed that the ill control group members had significantly lower IgG in May than the healthy ones. In August, the sick control group members had a significantly lower mean IgA salivary concentration; about one-third less compared to the level of healthy control group members.
This was an unexpected result, as the researchers had suggested that the highly trained athletes would be more prone to lower immunity and disease than the relatively more sedentary control group. "The onset of RTI and the lower mucosal immunity suggest that the regulation of effective immunity depends on psychological factors and lifestyle, rather than physiological factors. The higher age of the control group may also be a determining factor "A number of studies have pointed to a link between psychological stress and the onset of disease - after all, training at a high level can be very stressful. The results of this study suggest that lifestyle and self-management programs should be geared not only to coaches and officials, but also to the athletes themselves.
Did illness have any influence on the performance of the swimmers? The healthy swimmers outperformed the sick swimmers with an average international score (IPS) of 955 and 937. Scientifically, this difference means no statistical difference. But in the everyday world, it would be enough to move a swimmer's position from first, second, or third to a lower or no medal rank (fourth to eighth).
The researchers concluded that further studies needed to be made to further clarify the association between disease and competitive performance in professional athletes. (1)
Vitamin C for biathletes
According to a small study on Austrian biathletes, the intake of high doses of vitamin C after hard training does not compensate the impaired immune function again. The study was carried out during the strenuous "Schockel Classic" in Graz, which consists of 16.5 km uphill cycling and 2 km uphill, with a total elevation difference of 1100 m. Six male athletes took high doses of vitamin C (2 g per day) for 4 weeks before a race, while 4 other athletes did not take any dietary supplements and thus served as a control group. Blood samples were taken 15 minutes before and immediately after the biathlon race. The times of the participants were between 1h 7min and 2h 23min.
The researchers were most anxious to study the effects of vitamin C on the function of neutrophils. Neutrophils are the white blood cells that respond most quickly to the ingress of foreign bodies such as viruses or bacteria. Although neutrophils in the blood are actually elevated after exercise, inhibition of neutrophil function is considered a factor responsible for increasing the susceptibility of athletes to higher respiratory tract infections (URTIs).
Vitamin C treatment is intended to improve neutrophil function in patients who have recurrent boils (bumps caused by bacteria in the skin) and to avoid URTI in patients after hard training.
Analysis of blood samples after a race showed evidence of inhibited neutrophil function in all athletes. There was no difference between those taking vitamin C and the control group.
Increased blood levels of the stress hormones norepinephrine and epinephrine, which were shown to inhibit neutrophil function in laboratory tests, were found in all athletes. Conversely, they were attributed to neutrophil function, regardless of whether athletes took vitamin C or not.
"Our findings do not support the idea that taking vitamin C compensates for neutrophilic imbalances after a hard workout." Proof of its efficacy comes from studies in humans who already have an inhibited neutrophil function. "Since none of the athletes in our study showed any biotrophic neutrophil inhibition, this may explain why vitamin C treatment has no effect. Therefore, without an existing inhibited neutrophil function, athletes without vitamin C intake can not be recommended to compensate for the inhibited neutrophil function of exercise. "
Another argument against the revenue of high doses of vitamin C results from a new US study published in Science. She ratifies previous UK findings that taking high doses of vitamin C (500 mg / day) results in the production of "genotoxin", which can damage the DNA.