"To breathe or not to breathe... is that the question?"...
Reviewing confusion around Covid-19 and recreational activities within gyms and fitness facilities during the 2020 pandemic (Switzerland). Questioning if governing bodies need to be more innovative during difficult times. (Evidence Based)
Maskenpflicht (German)
Das Tragen einer Maske ist in allen Innenräumen Pflicht (ausgenommen Kinder und Jugendliche unter 16 Jahren). In grossen Räumlichkeiten kann auf das Tragen einer Maske verzichtet werden, sofern genügend Platz vorhanden ist (mindestens 15 m²pro Person bei aktiven Sportarten wie Group Fitness, Dance fit, Nia, etc./ 4 m2 bei ruhigen, stationären Sportarten wie Yoga, Pilates, Gymnastik auf der Matte)
Mask requirement (Direct translation)
The wearing of a mask is compulsory in all indoor areas (except for children and young people under 16 years of age). In large rooms, it is not necessary to wear a mask if there is enough space (at least 15m² per person for active sports such as group fitness, dance fit, Nia, etc./ 4m² for quiet, stationary sports such as Yoga, Pilates, Gymnastics on the mat). The above sections regarding mask requirements within fitness facilities are direct quotations from the Swiss government dated 28/10/20
Aerosol particles and respiratory velocities
The World Health Organisation defines that COVID-19 aerosol particles can be released into the surrounding environment when the respiratory tract's lining is overcome by force 1.
This might happen through exhalation and includes but is not exclusive to talking, singing, heavy or deep breathing, coughing and sneezing 1 2. Other factors that can affect the airborne range are humidity, temperature and ventilation. Exhalation velocities are measured in meters per second (m/s), e.g. normal breathing 1 m/s, talking 5 m/s, coughing 10 m/s, and sneezing 20-50 m/s 3. Some literature has concluded that even though respiratory activities with higher velocities may spread droplets and aerosols at an increased rate within enclosed environments, regular breathing is likely responsible for a higher percentage of contagion over the course of a day when insufficient safety measures are in place, and a lack of airflow is present 4.
Reading between the lines and applying some methodology
The example provided by the Swiss government lists disciplines that include various intensities and account for a wide range of physiological parameters. Broad strokes used by governing bodies may contribute to misunderstandings, misleading training facilities that may draw inaccurate conclusions. For example, 4m² has been deemed adequate space for "mat" or "stationary" activities which are interpreted as Yoga, Pilates and Gymnastics. Presumably, this is based on the assumption that these disciplines require less metabolic conditioning and a lower respiratory rate than exercises requiring 15m² . Although this may be true compared to heavy, vigorous activity, respiratory rates may depend on numerous factors from the specific type of training to the individual's experience, anthropometrics, strength, and fitness level 5. Considering the varied levels of respiratory frequency or intensity within a sporting activity, gas exchange or "turnover of oxygen and carbon dioxide" could be regarded as a method of baselining individuals to prescribe exercise intensity 6 7.
Perhaps on a more fundamental level when equipment is lacking, something as simple as measuring heart rate might help training facilities interpret the boundaries of exertion and safety levels when exercising indoors or within specific distances 8 9 10 11 12 13 Therefore, a prescribed "maximum range" of heart rate could help determine which exercises can be carried out within particular margins of the given square meterage in a training facility.
Descriptions of various intensities or (heart rates)
To highlight the lack of distinction and to further demonstrate the ambiguity, when looking at heart rate beats per minute (BPM), various types of yoga such as "Ashtanga" can elevate the heart rate over 125BPM, especially when performing challenging poses and particularly for inexperienced or unfit individuals 14. One study examining "Power yoga" showed heart rates upward of 170BPM 15. Additionally, these activities involve increased amounts of deep breathing which may contribute further to the range of air born particles 16. Pilates has also been classed as a "quiet, stationary" exercise even though some practices can increase the heart rate upward of 135BPM 17. Gymnastics falls into the same classification, yet evidence has shown heart rate averages ranging between 137 and upward of 190BPM and over 18 19 20. Although not mentioned, resistance training guidelines with barbells or machines again are equally unclear, even though they could potentially be classified as quiet, stationary activities. Heart rates within these disciplines are less significant markers of intensity, but examples have shown a maximum heart rate of 160BPM during heavy back squatting 21. Even though high-intensity workouts might elevate the heart rate beyond the anaerobic threshold, low to medium intensity could be classified as peaking at 175BPM based on a max of 200BPM, within that range, it may be possible to fit many disciplines that do not incorporate excessive respiratory rates.
Various training zones
(Table 1.) This table shows heart rate zones as well as the duration of training for each zone 22.
An example of recommendation
Here could lie the confusion on the classification of exercises and possibly where the less knowledgeable sectors may come unstuck with unclear definitions. All of the ranges listed above might fall in or out aerobic/anaerobic or metabolic conditioning heart rate zones that have been classed as quiet and stationary along with "Yoga, Pilates and Gymnastics on the mat".The chart above shows an example that training can be classified into low medium and high intensity. At heart rates during upper limits of physical exertion, oxygen consumption and breath-rate are maximum; this could be considered HIT (high-intensity training). Low to medium intensity training shows a possible 65-92% maximum heart rate or up to 160BPM. Based on a V02 max of 200. All of the activities listed above can fit into the MIT zone on the table above. This information is an example of the huge margins that can separate disciplines mainly due to individual response to a training stimulus and the discipline itself. The implications of setting vague or ambiguous guidelines such as these create a mechanism for gyms and training centres to interpret the rules in their way, which may not help fitness facilities remain open or a pandemic situation on the whole.
The Endurance Map
(Table 2.) The endurance map taken from "High-Intensity Interval Training and Agile Periodisation" (Mladen Jovanović et al 2018 permission granted) shows physiological markers of the anaerobic threshold of a max heart rate of 200BPM this further highlights which activities based on the previous evidence that might fit into the zones of low to medium intensity. (permission by the author granted for the above images)
Masks and Training is it Safe?
Although there is limited evidence at this time, It seems clear that exercising in masks increases a heightened physiological response due to heavier breathing, restricted ventilation and sympathetic response 23 . The accumulation of moisture can also negatively affect thermoregulation's respiratory mechanisms through impaired convection, evaporation, and radiation processes 24. Masks worn during moderate to heavy exercise may decrease oxygen consumption and increase carbon dioxide concentration in small amounts, creating negative symptoms in some individuals 24. It has been proposed to rest when the heart rate exceeds 150BPM or around 70% of the age-predicted heart rate (220-age) 25 26. With this in mind, activities should be adjusted according to an individual's ability, and masks should be changed when they become too moist. In summary, healthy subjects can exercise for short to moderate aerobic and anaerobic types of training with only minor changes in physiological parameters that are not negatively significant in healthy individuals, with most studies suggesting only mild physiological effects 27. The current guidelines at the time of this article highlight that it is not compulsory to wear masks during "quiet, stationary sports such as Yoga, Pilates, Gymnastics on the mat". However, based on the varied response in respiratory rates from individuals during a wide range of disciplines, it seems the logical conclusion for everyone to wear masks indoors to help reduce further cases of COVID-19
Mask Examples
(Fig 1.) Gives an example of average changes in physiological parameters throughout the exercise test performed by 16 healthy subjects without a mask, with a surgical mask, and with N95 respirator. A, Heart rate (beats/min). B, Respiratory rate (breaths/min). C, Oxygen saturation (%). D, Rated Perceived Exertion (RPE) Scale (score). Error bars represent 95% confidence interval 24
Conclusion
Additionally, better measures categorising disciplines and giving clear information on what is safe and acceptable based on scientific evidence or propositions. More explicitly information on mask-wearing and using physiological parameters; and scales to determine intensity levels of exercise and the potential associated risks that they may bring. This could help determine the best course of action and help dispel confusion in a pandemic. The challenges presented to many industries in 2020 are unprecedented, physically, psychologically and economically. This highlights the importance of health and fitness to maintain a strong body, mind and immune system at any time.
The information provided above intends to highlight the complexity of the situation and that it is not as cut and dry as the definitions laid out by the governing bodies. Working on more comprehensive solutions and sharing information on practical approaches between facilities and encouraging populations to continue training will give confidence that the authorities are doing all they can to develop a transparent strategy toward health and fitness during critical times.
References
3. Mittal R, Ni R, Seo JH. The flow physics of COVID-19. J Fluid Mech. 2020. doi:10.1017/jfm.2020.330