Face Masks whilst ExeRcIsing Trial (MERIT): a crossover randomised controlled study

Conference:

SAPC ASM 2022 - UCLan

Talk Code:

1D.5

Presenter:

Nicholas Jones

Twitter:

@drnrjones

Co-authors:

Nicholas Jones, Seren Marsh, Jason Oke, Kurosh Nikbin, Jonathan Bowley, FD Richard Hobbs and Trisha Greenhalgh

Author institutions:

University of Oxford Nuffield Department of Primary Care Health Sciences, Jesus College University of Oxford, Kings College London, University of Nottingham

Problem

Physical exertion is a high-risk activity for emission of aerosols, including the SARS-CoV-2 virus, but there is controversy around whether facemasks are safe and acceptable when exercising. We aimed to determine the safety and tolerability of healthy young adults wearing different types of facemask during moderate-to-high intensity exercise.

Approach

We conducted a crossover randomised controlled study, comparing a surgical, cloth and FFP3 mask to no mask during 15 minutes of exercise separated by 5 minutes rest. Participants were students aged 18-35 years, who exercised at least three times per week and had no pre-existing health conditions that restricted their activity. In a non-inferiority analysis, the primary outcome was changes in oxygen saturations (non-inferiority margin=2%). Secondary outcomes included changes in heart rate (non-inferiority margin=7bpm), mask comfort and perceived impact on exercise.

Findings

72 individuals (mean age 23.1 years) completed the study. Changes in oxygen saturations and heart rate did not exceed the pre-specified non-inferiority margin with any mask type compared to no mask. At the end of exercise the estimated average difference in oxygen saturations for the cloth mask was -0.07% (95%CI -0.39 to 0.25), for the surgical 0.28% (95%CI -0.04 to 0.60) and for the FFP3 -0.21% (95%CI -0.53 to 0.11). The corresponding estimated average difference in heart rate for the cloth mask was -1.20bpm (95%CI -4.56 to 2.15), for the surgical 0.36bpm (95%CI -3.01 to 3.73) and for the FFP3 0.52bpm (95%CI -2.85 to 3.89). The cloth mask was felt to be most difficult to exercise in by 56.3% of participants (n-=40) and the FFP3 mask by 38% (n=27). Wearing a facemask caused additional symptoms such as breathlessness (n=13, 18.1%), dizziness (n=7, 9.7%) and fatigue (n=6, 8.3%). 33 participants broadly supported facemask wearing during exercise, particularly indoors, 18 would agree to this if it were mandated and 22 were opposed.

Consequences

Exercising at moderate-to-high intensity wearing a facemask appears to be safe in healthy, young adults. Some students would be opposed to the mandatory wearing of facemasks for exercise but there was most support for wearing a surgical facemask during indoor exercise if needed to reduce the spread of COVID-19.

Submitted by:

Nicholas Jones

Funding acknowledgement:

Buff provided the cloth face masks for the study free of charge. NJ's is supported by a Wellcome Trust Doctoral Research Fellowship (grant number 203921/Z/16/Z). FDRH acknowledges support from the NIHR School for Primary Care Research, NIHR ARC Oxford and Thames Valley, and the NIHR Oxford BRC TG’s research is supported by Oxford NIHR Biomedical Research Centre (grant no BRC-1215-20008).