Background The role of portable high-efficiency particulate air (HEPA) filters for supplemental aerosol mitigation during exercise testing is unknown and might be relevant during COVID-19 pandemic. Research Question What is the effect of portable HEPA filtering on aerosol concentration during exercise testing and its efficiency in reducing room clearance time in a clinical exercise testing laboratory? Study Design and Methods Subjects were six healthy volunteers aged 20 to 56 years. In the first experiment, exercise was performed in a small tent with controlled airflow with the use of a stationary cycle, portable HEPA filter with fume hood, and particle counter to document aerosol concentration. Subjects performed a four-stage maximal exercise test that lasted 12 min plus 5 min of pretest quiet breathing and 3 min of active recovery. First, they exercised without mitigation then with portable HEPA filter running. In a separate experiment, room aerosol clearance time was measured in a clinical exercise testing laboratory by filling it with artificially generated aerosols and measuring time to 99.9% aerosol clearance with heating, ventilation, and air conditioning (HVAC) only or HVAC plus portable HEPA filter running. Results In the exercise experiment, particle concentrations reached 1,722 ± 1,484/L vs 96 ± 124/L ( P < .04) for all particles (>0.3 μm), 1,339 ± 1,281/L vs 76 ± 104/L ( P < .05) for smaller particles (0.3 to 1.0 μm), and 333 ± 209/L vs 17 ± 19/L ( P < .01) for larger particles (1.0 to 5.0 μm) at the end of the protocol in a comparison of mitigation vs portable HEPA filter. Use of a portable HEPA filter in a clinical exercise laboratory clearance experiment reduced aerosol clearance time 47% vs HVAC alone. Interpretation The portable HEPA filter reduced the concentration of aerosols generated during exercise testing by 96% ± 2% for all particle sizes and reduced aerosol room clearance time in clinical exercise testing laboratories. Portable HEPA filters therefore might be useful in clinical exercise testing laboratories to reduce the risk of COVID-19 transmission.

Background Characterization of aerosol generation during exercise can inform the development of safety recommendations in the face of COVID-19. Research Question Does exercise at various intensities produce aerosols in significant quantities? Study Design and Methods In this experimental study, subjects were eight healthy volunteers (six men, two women) who were 20 to 63 years old. The 20-minute test protocol of 5 minutes rest, four 3-minute stages of exercise at 25%, 50%, 75%, and 100% of age-predicted heart rate reserve, and 3 minutes active recovery was performed in a clean, controlled environment. Aerosols were measured by four particle counters that were place to surround the subject. Results Age averaged 41 ± 14 years. Peak heart rate was 173 ± 17 beat/min (97% predicted); peak maximal oxygen uptake was 33.9 ± 7.5 mL/kg/min; and peak respiratory exchange ratio was 1.22 ± 0.10. Maximal ventilation averaged 120 ± 23 L/min, while cumulative ventilation reached 990 ± 192 L. Concentrations increased exponentially from start to 20 minutes (geometric mean ± geometric SD particles/liter): Fluke >0.3 μm = 66 ± 1.8 → 1605 ± 3.8; 0.3-1.0 μm = 35 ± 2.2 → 1095 ± 4.6; Fluke 1.0-5.0 μm = 21 ± 2.0 → 358 ± 2.3; P-Trak anterior = 637 ± 2.3 → 5148 ± 3.0; P-Trak side = 708 ± 2.7 → 6844 ± 2.7; P-Track back = 519 ± 3.1 → 5853 ± 2.8. All increases were significant at a probability value of <.05. Exercise at or above 50% of predicted heart rate reserve showed statistically significant increases in aerosol concentration. Interpretation Our data suggest exercise testing is an aerosol-generating procedure and, by extension, other activities that involve exercise intensities at or above 50% of predicted heart rate reserve. Results can guide recommendations for safety of exercise testing and other indoor exercise activities.

Background: Data on the occurrence of syncope and presyncope with hemodynamic instability during graded exercise test (GXT) are limited. Methods: We reviewed the Mayo Integrated Stress Center database for non-imaging GXTs performed between January 2006 and December 2010 and registered syncopic/presyncopic episodes. Electronic medical records were reviewed for clinical information, outcomes, and mortality. SAS was used to provide background statistics. Results: During the study period, a total of 40,715 GXTs were performed on 33,885 unique patients, including 16,306 (40.0%) GXTs on patients with known cardiovascular disease (CVD). High risk for cardiac syncope is defined as prior cardiac arrest/ventricular tachycardia, ischemic cardiomyopathy, implanted defibrillator, history of atrial fibrillation, sotalol, amiodarone, LQTS, HOCM, aortic stenosis was identified in 3263 patients (6.0%), while risk factors for non-cardiac syncope (POTS, history of dizziness/spells/syncope, rest SBP < 100 mmHg, age ≥ 80 years, female age < 30 years, beta blocker use) were found in 15,925 patients (39.1%). Despite the presence of so many patients at risk, only 8 episodes of syncope occurred (0.020% per test; 0.023% per individual patient). Another 5 episodes of near-syncope with documented hypotension were aborted by the quick action of the testing staff (0.012% per test; 0.015% per individual patient). Only 1 patient (a 71yo M with severeCAD) required electrical cardioversion for ventricular fibrillation. None of the other patients, including all 6 women, presented with tachyarrhythmias. There were no deaths and no significant musculoskeletal trauma. Conclusion: Despite many patients with risk factors for cardiac and non-cardiac syncope in the cohort, syncope, and near-syncope with hemodynamic instability were very rare findings on guideline-directed GXTs.