The relationship between knee extensor strength and the lack of work in 60-and-older people: a cross-sectional study

Abstract

Objective: The purpose of this study was to cross-sectionally examine the association between physical fitness and lack of work among individuals 60 years and older who were interested in working.

Methods: The participants included 290 Japanese individuals (mean age (SD), 71.3 (5.5) years; age range, 60– 86 years; male, n = 76; female, n = 214). Isometric knee-extensor strength (KES) was measured using a leg strength measurement unit. The working situation and the reason for lack of work, i.e., concerns about one’s own physical fitness, were assessed using a self-reported questionnaire. This study defined lack of work as having no paid work for the past year. A logistic regression analysis was performed to examine the sex, age, and BMI-adjusted relationships between KES and lack of work.

Results: In total, 166 participants including 39 who were concerned about their own physical fitness were not working according to the abovementioned definition. For lack of work for all causes, the odds ratios (95% confidence interval) of the second and third KES tertiles of participants versus the first tertile were 0.67 (0.37-1.22) and 0.69 (0.37-1.27), respectively. For lack of work due to one’s own physical fitness, the odds ratios (95% confidence interval) of the second and third KES tertiles of participants versus the first tertile were 0.54 (0.23-1.28) and 0.33 (0.12-0.89), respectively.

Conclusion: The present study suggests that a high KES was associated with a lower proportion of individuals 60 years and older who lacked work. Further longitudinal studies are needed to examine the causal relationship.