In order to curb the rapid increase in new coronavirus infections, on 28 October 2020 the Federal Government and the federal states agreed on a second “Lockdown Light” which came into force on 2 November 2020. Due to the new measures, institutions and facilities associated with leisure activities were closed. These include gyms and similar facilities as well as recreational and amateur sports facilities.
A project launched by the Associate Professorship of Exercise Biology headed by Prof. Dr. Henning Wackerhage and Dr. Martin Schönfelder has now become especially relevant for these sectors. The research project “ExDrop: droplet and aerosol production during intensive physical exercise & implications for the risk of SARS-CoV-2 infection” is funded by the Federal Institute of Sports Science (BISp) with two posts over a period of one and a half years. Further project partners include Prof. Dr. Christian Kähler and Dr. Rainer Hain from the Institute of Fluid Mechanics and Aerodynamics at the University of the German Armed Forces in Munich, and Prof. Dr. Giorgio Buonanno from the University of Cassino/Italy.
Based on the “Concept for the reopening of fitness studios after the peak of the COVID 19 pandemic” drawn up in May 2020, the Associate Professorship of Exercise Biology recommended wearing masks in fitness studios and avoiding high-intensity physical activity. “The great unknown at that time was how many droplets and aerosols are produced, for example, when a high-intensity HIIT training session is completed,” says Prof. Wackerhage, explaining the initial situation.
According to Wackerhage, the respiratory minute volume can rise from five to ten litres per minute when resting to over 100 litres per minute for untrained athletes and over 200 litres per minute for endurance athletes which can become a significant risk factor during sport. Furthermore, weight training can also lead to strained breathing. “It is essential to emphasize that increased and altered breathing during sporting activities is an additional problem,” says Prof. Wackerhage. “This is because people infected with the coronavirus release more droplets and aerosols into their environment during intensive exercise and, also, presumably, during strained breathing."
“ExDrop” will now be applied to measure how many droplets and aerosols are produced in enclosed spaces and subsequently transported through the air during high-intensity exercise. These measurements in various exposure situations are simulated alongside mathematical models to obtain experimental data on droplet and aerosol production during sport and to quantify potential infection risks.
The two experiments consist of a gradually increasing bicycle ergometer exercise load and a strength test. Four men and four women between the ages of 18 and 40 were recruited for each of the two scenarios to also investigate any possible gender-specific effects.
The measurements will be used to determine the sizes and diameters of emitted droplets and aerosols as well as their respective frequencies.
The third step is to simulate the influence of exercise intensity on the risk of infection. The quantum emission rate of SARS-CoV-2-infected persons at different exercise intensities and during strength training will be calculated based on the measured data. A quantum refers to the amount of coronavirus in droplets or aerosol that is sufficient to infect a person.
“In this case, we have deliberately put together a multidisciplinary team to be able to predict the level of infection risk during sporting activities more precisely,” explains Prof. Wackerhage. “Because, this issue is not only highly relevant for fitness studios, but also for school sports, competitive sports or even the entire field of club sports! If the extent of the risks is known, measures such as those currently being adopted by the Federal Government can be defined in a far more specific manner."
“It is particularly important to be able to measure these risks when assessing lockdowns,” adds Dr. Martin Schönfelder, Research Associate at the Associate Professorship of Exercise Biology. “Currently, gyms and all other facilities have been closed without any clear indication of the actual infection risks. For example, if the measurements and calculations were to demonstrate that the risk is lower than has currently been assumed, then it would be possible to adopt more targeted protective measures that are specifically adapted to the infection risks involved. The aim of our research is to develop scientifically sound advice relevant to the practice of sports on the basis of our results."
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Contact:
Prof. Dr. Henning Wackerhage
Associate Professorship of Exercise Biology
Georg-Brauchle Ring 60/62
80992 Munich
Phone: 089 289 24480
E-mail: Henning.Wackerhage(at)tum.de
Dr. Martin Schönfelder
Associate Professorship of Exercise Biology
Georg-Brauchle Ring 60/62
80992 Munich
phone: 089 289 24410
e-mail: Martin.Schoenfelder(at)tum.de
Text: Romy Schwaiger
Photos: Associate Professorship of Exercise Biology