Participants
perspiration, knee pain, chest heaviness
Ninety volunteers were recruited through the Outpatient Clinic of Cairo University's Faculty of Physical Therapy. The sample size was calculated using the G.Power program version 3.1. From these, 70 were selected to participate according to the inclusion criteria. However, during the study, ten participants were excluded for the following reasons: seven participants refused to participate in the first session, two participants had knee pain, one participant experienced chest heaviness in the first session, and ten were excluded at the study's outset for different reasons. The study consort flow chart is represented in Fig. Study flow chart.The surgical mask group performed a controlled endurance exercise while wearing a suitable fit surgical mask with three layers of protection (n = 35). Controlled exercise performed within the symptom or exertion threshold of participants. It is based on physically experiences such as increased heart rate, increased respiration or breathing rate, increased perspiration, and muscular exhaustion that occur during physical exhaustion.The mask-less group will perform a controlled endurance exercise without wearing masks (n = 35).