Physical activity and health service utilization among older people. 
Rising health care use among older people presents a challenge to medical care.  Physical activity (PA) is beneficial; however, it is unknown if initiating PA among the very old reduces health service use.  We examined the effects of changing PA levels on emergency room (ER) visits and hospitalization at ages 78 and 85.  A representative sample (born 1920-1921) from the Jerusalem Longitudinal Cohort Study (1990-2010) were assessed at ages 78 and 85 for self-reported PA; ER visits and hospitalization; and social, functional, and medical domains.  We examined 896 and 1173 subjects at ages 78 and 85, respectively.  ER usage at ages 78 and 85 respectively was lower among active subjects (15.8% vs 37.4%, P < .0001; 30.6% vs 50.8%, P < .0001), as was hospitalization (10.5% vs 16.7%, P < .05; 22.1% vs 37.8%, P < .0001).  We adjusted for gender, education, loneliness, functional dependence, cognitive impairment, depression, diabetes, heart disease, hypertension, neoplasm, renal disease, self-rated health, body mass index, and smoking.  PA at age 78 was associated with a reduced likelihood of ER visits (odds ratio [OR] 0.49, 95% confidence interval [CI] 0.27-0.89), but not hospitalization (OR 1.14, 95% CI 0.54-2.42); at age 85 with a reduced likelihood for ER visits (OR 0.72, 95% CI 0.52-0.99) and hospitalization (OR 0.68, 95% CI 0.48-0.98).  Compared with subjects consistently active at ages 78 and 85, initiating PA between ages 78 and 85 resulted in similar lower likelihood of ER visits (OR 0.6, 95% CI 0.23-1.56) and hospitalization (OR 1.20, 95% CI 0.48-3.02); stopping PA and never being active between 78 and 85 were respectively associated with increased ER visits (OR 1.72, 95% CI 1.02-2.88; OR 2.18, 95% CI 1.04-4.57) and hospitalization (OR 1.85, 95% CI 1.06-3.23; OR 2.01, 95% CI 0.92-4.4).  Among the oldest old, not only continuing but also becoming physically active is associated with reduced health service use.  Initiating PA among the very old should be encouraged.