Acute viral respiratory infections have proven to be a major health threat, even after the Corona Virus Disease 2019 (COVID-19) pandemic. We aimed to check whether the presence or absence of an acute respiratory infection such as COVID-19 can influence the physical activity of older hospitalised patients. We cross-sectionally studied patients aged ≥60 years, hospitalized during the pandemic in the non-COVID-19 and COVID-19 ward at the University Hospital, Kraków, Poland. Using activPAL3 technology, we assessed physical activity for 24 h upon admission and discharge. In addition, we applied the sarcopenia screening tool (SARC-F); measured the hand grip strength and calf circumference; and assessed the Modified Early Warning Score (MEWS), age-adjusted Charlson Index, SpO2%, and length of stay (LoS). Data were analysed using SAS 9.4. The mean (min, max) age of the 31 (58% women, eight with COVID-19) consecutive patients was 79.0 (62, 101, respectively) years. The daily time (activPAL3, median [p5, p95], in hours) spent sitting or reclining was 23.7 [17.2, 24] upon admission and 23.5 [17.8, 24] at discharge. The time spent standing was 0.23 [0.0, 5.0] upon admission and 0.4 [0.0, 4.6] at discharge. The corresponding values for walking were 0.0 [0.0, 0.4] and 0.1 [0.0, 0.5]. SARC-F, admission hand grip strength, calf circumference, and LoS were correlated with physical activity upon admission and discharge (all < 0.04). For every unit increase in SARC-F, there was a 0.07 h shorter walking time upon discharge. None of the above results differed between patients with and without COVID-19. The level of physical activity in older patients hospitalised during the pandemic was low, and was dependent on muscular function upon admission but not on COVID-19 status. This has ramifications for scenarios other than pandemic clinical scenarios.