Background: Measurement of indoor physical activity at home in older adults who have difficulty performing outdoor activities is a key to documenting baseline physical activity levels to guide physical activity interventions aimed at reducing the rate of decline in mobility.
Purpose: The purpose of this study was to describe indoor life-space mobility at home (LSH) and examine the association between LSH and mobility-related physical functions in older adults who have difficulty performing outdoor activities.
Methods: The participants were 20 community-dwelling older adults (mean age [SD], 76.6 [5.1] years) receiving home-care rehabilitation. Participants were assessed for LSH and physical function related to mobility. Assessments included isometric knee extensor strength, the Timed Up and Go (TUG) Test, functional status (a 13-item Motor subscale of Functional Independence Measure, the Tokyo Metropolitan Institute of Gerontology Index of Competence, and outdoor life-space mobility (life-space assessment [LSA]). Life-space mobility at home documented how far and how often participants moved from a bedroom to 4 destinations (entrance, dining room, bathroom, and toilet) at home with or without assistance during the week prior to the assessment.
Results: Reliability of LSH was high (intraclass correlation coefficient [ICC] (1,1) = 0.80, ICC (1,2) = 0.89). Simple bivariate correlations showed a significant relationship between LSH and isometric knee extensor strength (rs = 0.59, P = .01) and TUG Test (rs = −0.74 P = .01). Life-space mobility at home showed moderate correlations with the Functional Independence Measure (rs = 0.58, P = .01) and Tokyo Metropolitan Institute of Gerontology Index of Competence (rs = 0.49, P = .03), but no significant correlation with the LSA (rs = 0.33, P = .17).
Discussion: Regarding intrarater reliability, the ICCs for measuring the LSH indicated high reproducibility. The results suggest that the LSA mainly reflects outdoor life-space mobility and activity rather than indoor life-space whereas the LSH reflects indoor life-space mobility and is considered an indicator of a major decline in indoor activities and physical abilities.
Conclusions: The LSH concept can measure with high reliability and concurrent or discriminant validity, and it is a different concept from outdoor life-space mobility. Life-space mobility at home may be an important factor associated with physical functions related to mobility and functional status, and measuring LSH may be useful to assess current indoor life-space activity in older adults who have difficulty performing outdoor activities.