Table 6.

Associations of poor muscle strength, mobility limitation, and physical activity levels with presence of COVID-19-like symptoms (0 vs 1 +) in the physical activity assessment sub-sample by age groups. Results from logistic regression models after mutually adjusting by all exposures (n = 587)

	Total sub-sample		Age (< 70 years)		Age (≥ 80 years)
	OR (95% CI)	p value	OR (95% CI)	p value	OR (95% CI)	p value
Poor muscle strength
No	Ref.	Ref.	Ref.	Ref.	Ref.	Ref.
Yes	1.5 (1.0–2.2)	0.066	1.1 (0.7–1.9)	0.625	3.2 (1.4–7.1)	0.004
Mobility limitation
No	Ref.	Ref.	Ref.	Ref.	Ref.	Ref.
Yes	0.7 (0.4–1.5)	0.389	2.0 (0.5–8.2)	0.343	0.6 (0.3–1.4)	0.264
Physical activity
Active	Ref.	Ref.	Ref.	Ref.	Ref.	Ref.
Inactive	1.0 (0.6–1.5)	0.962	1.0 (0.6–1.7)	0.942	0.9 (0.4–1.8)	0.705

Muscle strength, mobility limitation, and physical activity were analyzed together, further adjusting by age sex, education level, living alone, location where most time spent, frequency of going out, use of public transport, number of chronic cardiovascular, neuropsychiatric, and musculoskeletal diseases, COPD, asthma, and other respiratory diseases. Poor muscle strength defined as a chair stand test time below the median of the distribution (i.e., ≥ 11 s). Mobility limitation defined according to a previously suggested clinical cut-off for walking speed (i.e., < 0.8 m/s). Physical inactivity defined according to current guidelines’ definition of moderate-to-vigorous physical activity levels (i.e., < 150 min/week). Interaction with age: poor muscle strength (yes vs no) # age (≥ 80 years vs < 70 years): OR = 2.25; p = 0.077. Mobility limitation (yes vs no) # age (≥ 80 years vs < 70 years): OR = 0.26; p = 0.094. Physical activity (inactive vs active) # age (≥ 80 years vs < 70 years): OR = 0.93; p = 0.866