Table 1 Study inclusion and exclusion criteria

i) Aged 50–85 years

ii) COVID-19 vaccinated, i.e. at least two doses of the NHS-approved vaccine

iii) COVID group: PCR- or LFT-confirmed COVID-19 diagnosis between 28 days post-infection and < 18 months from initial visit

iv) Non-COVID group: never received a positive COVID-19 diagnostic test using PCR or LFT and during periods when testing was not available

v) Did not have symptoms that could have been COVID-19

i) Known chronic respiratory or cardiovascular conditions, i.e. COPD, emphysema, pulmonary hypertension, coronary artery disease

ii) Severe hypertension (systolic blood pressure > 180 mmHg, diastolic blood pressure > 120 mmHg)

iii) Acute or chronic neurological impairment or progressive neurological disease

iv) Use of medication known to directly affect cardiac function (i.e. beta-blockers)

v) Current smoker

vi) Body mass index > 35 kg/m²

vii) Previously ventilated during COVID-19 infection

viii) Exceeding current physical activity guidelines defined by the WHO