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I will outline the results of two scientific experiments that sought to investigate these issues.
Both studies examined the effect of one of two types of masks (surgical and FFP2/N95) on exercise capacity and parameters during a graded refusal test on a bicycle ergometer, compared to performing the exercise without a mask. In both experiments, each subject performed 3 trials (without mask, in surgical mask, in FFP2/N95 mask) in a randomized order at least 24 or 48 hours apart. The generated power, multiple cardiorespiratory parameters, as well as subjective parameters like comfort and perceived exertion rate were studied.
Below are 2 figures with the results of one of the experiments, conducted by researchers from Israel [1].
Figure 1. Average changes in physiological parameters during a graded exercise test performed by 16 subjects without masks, in surgical masks and in N95 type masks.
A - Heart rate (strokes/min). B - Respiratory rate (breaths/min). C - Blood oxygen saturation (%). D - Rate of perceived exertion (scale of 1-10).
As can be seen, none of the above parameters changed significantly when the effort was performed in a mask, regardless of its type. The apparent differences in Figure C are due to the very high Y-axis cutoff; in fact, the maximum differences are less than 1 percentage point.
Fig. 2. The value of the partial pressure of CO2 in exhaled air (end-expiratory CO2) during graded exercise without a mask and in two different types of masks: (surgical) and N95
The value of CO2 partial pressure showed significant differences at some levels of exercise severity, especially between performing exercise without a mask and performing exercise with a mask type FFP2 / N95
The main conclusion of this experiment was that healthy, young people can safely perform heavy exercise in both types of masks (surgical and FFP2/N95).
In the second experiment, researchers from Leipzig [2] measured a larger number of parameters, especially respiratory. The basic results can be seen in Figure 3.
Fig. 3. The effect of performing exercise in a surgical mask (sm), in a FFP2/N95 mask (ffpm) compared to exercise performed without a mask on: relative maximal power (Pmax/kg), relative maximal oxygen utilization (VO2Max/kg), ventilation (VE) and general discomfort.
The results showed a marked decrease in exercise capacity, a deterioration in respiratory parameters a decrease in comfort. In the case of FFP2 / N95 masks, this effect was much more pronounced than in the case of exercise in a surgical mask. The conclusion of the German researchers was that among young people, ventilation, cardiorespiratory capacity and comfort were reduced by exercise in surgical masks and clearly impaired in FFP2 / N95 masks.
So we have two similarly conducted experiments, with different final results and different conclusions. The differences may be partly due to methodological details. In the German study, exertion subjects had spirometric rubber masks additionally applied to the masks whose effects were studied, which was not the case in the Israeli study. On the other hand - the subjects, described as performing exertion without a mask, also had spirometric masks on during the German study.
Anyway - no conclusion states that intense exertion in a mask can pose any danger. It may deteriorate (or not) the ability, comfort, increase the load on the respiratory muscles, but for healthy people it will not be dangerous, and in the case of ordinary surgical masks the problems mentioned will be minimal.
Paradoxically, there are special masks on the market - so-called altitute simulating masks, which were designed to simulate altitude training precisely by making breathing more difficult. Of course, there can be no talk of any simulation of altitude training here, because the physiological mechanism of such training is completely different, but such masks (as well as special mouthpieces that increase respiratory resistance) have been used in sports for years as a part of respiratory muscle training.
Literature:
1. Epstein, D., Korytny, A., Isenberg, Y. et al.
Return to training in the COVID-19 era: The physiological effects of face masks during exercise.
Scand. J. Med. Sci. Sports. 2020;00:1–6.
DOI: 10.1111/sms.13832
2. Fikenzer, S., Uhe, T., Lavall, D. et al.
Effects of surgical and FFP2/N95 face masks on cardiopulmonary exercise capacity.
Clin Res Cardiol (2020).
DOI: 10.1007/s00392-020-01704-y
