Results
dizziness, breathlessness
All 72 volunteers (mean age 23.9) completed the study. Changes in oxygen saturations did not exceed the prespecified non-inferiority margin (2% difference) with any mask type compared with no mask. At the end of exercise, the estimated average difference in oxygen saturations for cloth mask was −0.07% (95% CI −0.39% to 0.25%), for surgical 0.28% (−0.04% to 0.60%) and for FFP3 −0.21% (−0.53% to 0.11%). The corresponding estimated average difference in heart rate for cloth mask was −1.20 bpm (95% CI −4.56 to 2.15), for surgical 0.36 bpm (95% CI −3.01 to 3.73) and for FFP3 0.52 bpm (95% CI −2.85 to 3.89). Wearing a face mask caused additional symptoms such as breathlessness (n=13, 18%) and dizziness (n=7, 10%). 33 participants broadly supported face mask wearing during exercise, particularly indoors, but 22 were opposed.