Table 7.

Associations of poor muscle strength, mobility limitation, and physical activity with number of COVID-19-like symptoms in the total sample and by age groups. Results from linear regression models

	Total sample		Age (< 70 years)		Age (≥ 80 years)
	β (95% CI)	p value	β (95% CI)	p value	β (95% CI)	p value
Poor muscle strength (N = 904)
No	Ref.	Ref.	Ref.	Ref.	Ref.	Ref.
Yes	0.04 (− 0.2 to 0.3)	0.708	− 0.13 (− 0.5 to 0.2)	0.426	0.28 (0.04 to 0.5)	0.024
Mobility limitation (N = 904)
No	Ref.	Ref.	Ref.	Ref.	Ref.	Ref.
Yes	− 0.10 (− 0.4 to 0.2)	0.484	0.11 (− 0.7 to 0.9)	0.799	− 0.16 (− 0.4 to 0.8)	0.199
Physical activity (n = 587)
Active	Ref.	Ref.	Ref.	Ref.	Ref.	Ref.
Inactive	0.09 (− 0.2 to 0.4)	0.502	0.20 (− 0.2 to 0.6)	0.320	− 0.07 (− 0.4 to 0.3)	0.663

Models adjusted 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): β = 0.32; p = 0.130. Mobility limitation (yes vs no) # age (≥ 80 years vs < 70 years): β = − 0.44; p = 0.232. Physical activity (inactive vs active) # age (≥ 80 years vs < 70 years): β = − 0.26; p = 0.313