TABLE 4.

Threshold effect analysis of the relationship between physical exercise and score of the Digit Symbol Substitution test in the short-sleep elders (based on Model 2).

	β (95% CI)
One-line linear regression model	0.099 (0.037, 0.163)
Two-piecewise linear regression model
Exercise < 8.0 (100*MET-minutes/week)	0.555 (0.332, 0.778)
Exercise ≥ 8.0 (100*MET-minutes/week)	−0.044 (−0.136, 0.048)
Log-likelihood ratio test

Age, sex, race, marital status, education, poverty status, body mass index, smokers, alcohol drinkers, diabetes mellitus, and cardiovascular diseases were adjusted.