INDOOR ENDURANCE EXERCISE PROVOKES HIGHER AEROSOL PARTICLE EMISSION AND POSES A HIGHER RISK OF INFECTION THAN RESISTANCE EXERCISE

INTRODUCTION: Pathogens such as severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2), influenza, and rhinoviruses are transmitted by airborne aerosol respiratory particles that are exhaled by infectious subjects. We have previously reported that the emission of aerosol particles increases on average 132-fold from rest to maximal endurance exercise [1]. The aims of this study are to first measure aerosol particle emission during an isokinetic resistance exercise at 80% of the maximal voluntary contraction until exhaustion, second to compare aerosol particle emission during a typical spinning class session versus a three-set resistance training session. Finally, we then used this data to calculate the risk of infection during endurance and resistance exercise sessions with different mitigation strategies. METHODS: We recruited 24 healthy participants (age: 21 to 37 years): eight of them for the endurance training session, eight for a resistance training, and eight for an isokinetic resistance training. In each training setting, we included four women and four men. The BMI of the participants ranged between 20.7 kg/m2 and 37 kg/m2 in the resistance exercise groups due to high muscle mass. In the endurance exercise group, the BMI ranged from 20.7 kg/m2 to 26.5 kg/m2. To measure ventilation and particle emission we coupled a spiroergometry device (Metalyzer; Cortex Medical™) with a particle counter (Palas Promo 3000 with Welas 2300 sensor, Palas GmbH) in a closed system. All measurements were performed in a clean air tent with reduced aerosol particle concentration (<150 particles/L compared to >30,000 particles/L in the ambient air). The airspace in the tent was flooded with cleaned air (H14 filter quality), and subjects directly inhale filtered air. RESULTS: During a set of isokinetic resistance exercise, aerosol particle emission increased 10-fold from 5,400 ± 1,200 particles/min at rest to 59,000 ± 69,900 particles/min during a set of resistance exercise