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Journal of Epidemiology logoLink to Journal of Epidemiology
. 2017 Jun 9;27(11):538–545. doi: 10.1016/j.je.2016.11.004

Leisure-time physical activity and risk of disability incidence: A 12-year prospective cohort study among young elderly of the same age at baseline

Takashi Matsunaga a,∗, Mariko Naito a, Kenji Wakai a, Shigekazu Ukawa b, Wenjing Zhao b, Satoe Okabayashi c, Masahiko Ando d, Takashi Kawamura c, Akiko Tamakoshi b
PMCID: PMC5608599  PMID: 28606710

Abstract

Background

To clarify the role of physical activity in preventing disability in Japan, we investigated the association between amount of leisure-time physical activity and incidence of disability among the young elderly.

Methods

In the New Integrated Suburban Seniority Investigation (NISSIN) project conducted from 1996 to 2013, we followed 2888 community-dwelling adults aged 64–65 years with no history of cerebrovascular disease for a median follow-up of 11.6 years. Disabilities were defined as follows based on the classifications of the Japanese long-term care insurance system: 1) support or care levels (support levels 1–2 or care levels 1–5); 2) care levels 2–5; 3) support or care levels with dementia; and 4) care levels 2–5 or death. In addition, we also assessed 5) all-cause mortality.

Results

After controlling for sociodemographic, lifestyle, and medical factors, male participants reporting an activity level of 18.1 metabolic equivalent (MET)-hours/week (the median among those with activities) or more had 52% less risk of being classified as support or care levels with dementia compared with the no activity group (hazard ratio 0.48; 95% confidence interval, 0.25–0.94). No significant association was found among women between amount of leisure-time physical activity and incidence of disability.

Conclusion

We identified an inverse dose–response relationship between the amount of leisure-time physical activity and the risk of disability with dementia in men. Therefore, a higher level of physical activity should be recommended to young elderly men to prevent disability with dementia.

Keywords: Leisure-time physical activity, Disability, Elderly

Highlights

  • •

    We examined associations between physical activity and disability incidence.

  • •

    We quantified amount of leisure-time physical activity.

  • •

    A dose–response relationship was found for the risk of disability with dementia.

Introduction

In developed and developing countries alike, increases in longevity are accompanied by increases in the number of individuals with disability.1 Worldwide, from 1990 to 2013, estimated years lived with disability (YLDs) increased 42.3%, from 537.6 million to 764.8 million.1 On the other hand, in Japan, the national long-term care insurance (LTCI) system operated by local governments covers 90% of the health care costs for middle-aged and elderly individuals with disability. When the LTCI system was launched in fiscal year (FY) 2000, the number of beneficiaries was 2.56 million. By 2012, this number had more than doubled, reaching 5.61 million from among the total population of 127 million.2 Because disability limits social participation, lowers quality of life, and makes it difficult to live independently in the community,3, 4, 5 health care providers should aim to prevent the incidence of disability in elderly people.

Many studies have reported that regular physical activity (total physical activity, including activities of daily life [e.g., working and housekeeping], leisure-time physical activities, and walking) reduced the risk of disability in the elderly.6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42 In addition, some reviews and guidelines have suggested the appropriate activity level for the elderly population.40, 42, 43 For example, a Japanese guideline recommended performing at least 10 metabolic equivalent (MET)-hours/week in physical activity at any intensity for adults aged 65 years or older.43 However, a number of issues remain unclear. First, few studies have measured the intensity and duration of physical activity quantitatively.7, 14, 17, 18, 32 Therefore, the current guidelines for physical activity require validation.40 Second, common physical activities vary among populations.44 Therefore, even if the frequency and duration of physical activity are similar, the amount may be different. However, in Japan, many studies have only examined the association between general measures of physical activity (e.g., walking time or frequency and total exercise frequency) and incidence of disability.9, 24, 27, 34, 37 Third, age is one of the most important risk factors for the incidence of disability.45 Previous studies have mainly applied multivariate analysis to adjust for the effect of age,6, 7, 8, 9, 10, 12, 14, 15, 17, 18, 20, 21, 22, 24, 25, 26, 27, 29, 30, 31, 32, 34, 35, 36, 37, 38, 39 but it may be difficult to fully control for confounding by age.46

Therefore, in this study, we attempted to quantitatively assess leisure-time physical activity (sports and recreational activities) and follow-up long-term disability onset prospectively among the elderly of about the same age in a Japanese cohort.

Methods

Study design and participants

This study was conducted as part of the New Integrated Suburban Seniority Investigation (NISSIN) project, a prospective cohort study targeting adults who were approaching 65 years old at baseline (the young elderly). The methods of that project and the characteristics of the participants have been described elsewhere.47 The participants were community-dwelling elderly in a suburban area (Nisshin city). All participants were invited to undergo a medical checkup and asked to complete a questionnaire on sociodemographic, lifestyle, comorbidity, and psychological factors.

From 1996 to 2005, 3073 individuals participated in the baseline survey, which was conducted each year in June. We excluded three and one persons who had relocated or had received an LTCI certification before the checkup, respectively. We also excluded 140 persons who had a history of cerebrovascular disease before the checkup and 41 individuals who had relocated or died before the start of the LTCI system (April 1, 2000). Ultimately, 2888 participants were included in the present analysis.

Informed consent and approval of the study protocol

Informed consent was obtained from all participants before conducting the medical checkups. For the questionnaire-based study, oral consent was obtained using an opt-out approach until 2001, and written consent was obtained using an opt-in approach thereafter. The study protocol was approved by the ethics committees of the Nagoya University Graduate School of Medicine, the National Center for Geriatrics and Gerontology of Japan, the Aichi Medical University School of Medicine, and the Hokkaido University Graduate School of Medicine.

Exposure assessment

At baseline, participants reported the type, frequency, and duration per episode of their leisure-time physical activity in the previous year. Activity types listed in the questionnaire and their assigned intensity (METs) are as follows: running or jogging: 7.0; swimming: 5.8; calisthenics: 3.8; baseball or softball: 5.0; tennis: 7.3; golf: 4.8; gateball (Japanese croquet): 3.3; and mountain climbing or hiking: 6.5.48 For the response of “other types” of activity (non-pre-coded activity), we applied a weighted-average intensity of 3.9 METs based on the data provided in a free comment field because only partial information regarding non-pre-coded activity types (25%) was available. Although the participants who responded “other types” of activity provided the type of activity, only a data file was kept for most of the participants (75%), and the type of “other” activity was not included in this file. Therefore, we calculated the weighted-average intensity for participants whose questionnaires were kept and applied that value to all the participants. We then calculated the amount of activity (MET-hours/week) by multiplying intensity, duration, and frequency. In accordance with existing guideline for physical activity,42 we only counted sessions lasting 10 min or longer.

Covariates

The following demographic variables were considered: year of participation in the study (continuous variable); currently working (yes or no); marital status (married or other [single, divorced, or widowed]); and educational attainment (junior college and higher or high school and lower). Lifestyle variables were: smoking status (never, former, or current); alcohol consumption (men: none, ≤23 g/day, or >23 g/day; women: none or current drinkers); body mass index (BMI; <18.5, 18.5–24.9, or ≥25.0 kg/m2); social activity score49 (in tertiles; men: ≤25, 26–28, or 29–54 points; women: ≤27, 28–31, or 32–54 points; items on work, sports, and recreational activities were excluded in this study because they were considered as exposure or other covariates); and total walking time per day, including work and housekeeping (<30 min, 30 min – 1 h, 1–2 h, or ≥2 h).

We included hypertension, dyslipidemia, diabetes mellitus, and neuralgia and/or low back pain as comorbidity variables in the analysis. Hypertension was defined as systolic blood pressure ≥140 mm Hg, diastolic blood pressure ≥90 mm Hg, and/or self-reported medication for hypertension. Dyslipidemia was defined as serum low-density lipoprotein (LDL) cholesterol ≥140 mg/dL (estimated using the Friedewald equation if triglycerides <400 mg/dL) or LDL cholesterol ≥170 mg/dL (estimated as total cholesterol minus high-density lipoprotein [HDL] cholesterol if triglycerides ≥400 mg/dL), HDL cholesterol <40 mg/dL, triglycerides ≥150 mg/dL, and/or self-reported medication for hyperlipidemia. Diabetes mellitus was defined as blood hemoglobin A1c ≥ 6.1% (based on the former method of the Japan Diabetes Society, equivalent to ≥6.5% in the National Glycohemoglobin Standardization Program [NGSP]),50 fasting plasma glucose ≥126 mg/dL, and/or self-reported medication for diabetes mellitus. All participants underwent health checkups and provided blood samples the morning after an overnight fast. History of neuralgia and/or low back pain was reported as none, cured, under treatment, or leaving; the last two categories were combined because of the small number of subjects in each category. We used the short version of the Geriatric Depression Scale (GDS) as a screening test for depression and regarded six points or higher as probable depression.51

Follow-up and outcomes

We followed-up the participants prospectively for qualification as an LTCI recipient or death from baseline through the end of December 2013. Participants' LTCI certifications were surveyed by the local government of Nisshin city. We identified all-cause mortality using the resident registry.

In Japan, all individuals aged 65 years or older, or those aged 40–64 years who suffer from age-related diseases are eligible for LTCI benefits. When a person applies to his/her municipality for LTCI benefits, an authorized care manager examines his/her physical and mental status using a standardized questionnaire. Severity of dementia is assessed concurrently based on the “Independence Criteria of Daily Living for the Demented Elderly”.52 The responses to the questionnaire are processed using computer software, and the time required for care is estimated. Finally, the certification board, which includes medical doctors and nurses, determines the level of long-term care needed based on the estimated time required for care, as well as on comments from the applicant's family physician.53

The LTCI certifications consist of the following seven levels: support levels 1–2 and care levels 1–5. Support levels 1 and 2 are defined as “the patient is independent in basic activities of daily living, but requires some assistance in instrumental activities of daily living”, care level 1 as “the patient requires partial assistance in instrumental activities of daily living”, care level 2 as “the patient requires some assistance in basic activities of daily living”, and care level 5 as “the patient requires total assistance in basic activities of daily living and cannot live without assistance”.54 In addition to the level of care required, the severity of dementia is graded as follows: independent; I; IIa; IIb; IIIa; IIIb; IV; and M. Level I is defined as “the patient has some dementia, but can live independently at home and in society,” level IIa as “although the patient has a few symptoms or behaviors that disturb daily living, or difficulty in communication outside the home, they can live independently under another's attention,” and level M as “the patient has severe mental symptoms, behavioral and psychological symptoms of dementia, or severe physical disease, and therefore requires special treatment.”52

We defined the incidence of disability in the follow-up based on LTCI certification and mortality as follows: i) support or care levels (i.e., support levels 1–2 or care levels 1–5); ii) care levels 2–5; iii) support or care levels with dementia (level IIa or higher); and iv) care levels 2–5 or death. We considered care levels 2–5 as severe disability because participants with care levels 1–5 had significantly lower ADL ability than those with support levels 1–2,55 and for consistency over the follow-up period; the former care level 1 was divided into support level 2 and care level 1 in 2008. In addition, we assessed v) all-cause mortality.

Statistical analysis

Because many of the participants did not engage in any leisure-time physical activity, we divided the participants into the following three groups according to their amount of activity: “no activity group”; “less than or equal to median group”; and “more than median group”. The median was computed only in those with leisure-time physical activity. We tested for statistical differences in background characteristics between groups using the chi-squared test of independence.

Person-years of follow-up were counted from baseline (medical checkup) to LTCI certification, death of any cause, relocation from the study area (Nisshin city), or December 31, 2013, whichever occurred first. We treated death as censoring, except in the analysis that included mortality as an outcome. The LTCI system was launched in April 1, 2000, so we started follow-up from April 1, 2000 for those persons who had participated in the baseline survey until March 2000.

Next, we examined associations between the amount of leisure-time physical activity and incidence of disability or mortality using Cox proportional hazard models. We performed a trend test by entering a variable scored as 0, 1, or 2 for the three groups with increasing physical activity as a single variable in the model. Because the association between amount of physical activity and incidence of disability differed considerably between sexes, we examined associations by sex. We calculated crude hazard ratios (HRs) in model1; HRs adjusted for year of participation, work, marital status, educational attainment, smoking and drinking habits, and BMI in model 2; and HRs adjusted for covariates in model 2 plus comorbidity (hypertension, diabetes mellitus, dyslipidemia, and neuralgia and/or low back pain), GDS scores, social activity, and total walking time per day in model 3.

In addition, we repeated the fully-adjusted Cox regression (model 3) as sensitivity analyses: i) by excluding events within 3 years from baseline; ii) by excluding those who had participated in the study until 1999; and iii) by excluding LTCI certification through March 31, 2002.

All statistical analyses were performed using Stata software (version 13.1; Stata Corp LP, College Station, TX, USA). Values of P < 0.05 were considered statistically significant.

Results

During a median follow-up of 11.6 years, we newly identified 396 LTCI certifications for support or care levels (13.7%), 172 for care levels 2–5 (6.0%), and 162 for support or care levels with dementia (5.6%). We also recorded 307 deaths (10.6%) and 424 composite outcomes of LTCI certifications for care levels 2–5 and death (14.7%). The proportion of participants with any leisure-time physical activity was 54.5% for men and 48.0% for women, and the median amount of leisure-time physical activity in those with any leisure-time physical activity was 18.0 MET-hours/week for men and 13.4 MET-hours/week for women. Men and women with higher amounts of leisure-time physical activity were more likely to participate in this study later, drink more alcohol, participate in social activities more frequently, and walk for longer times, whereas they were less likely to be currently working and in a depressive state (Table 1). Moreover, men who had a higher amount of leisure-time physical activity were more likely to be highly educated and have a history of diabetes mellitus, and less likely to be current smokers. The most common leisure-time physical activities were golf (23.8%), running or jogging (14.4%), and calisthenics (7.9%) in men, and calisthenics (13.9%), running or jogging (10.8%), and swimming (10.3%) in women. In addition, 21.0% of men (n = 303) and 24.6% of women (n = 355) reported activities other than the pre-coded types. Such activities noted in the free comment field included walking (46.9% of all non-pre-coded activities), table tennis (10.9%), and dancing (8.9%).

Table 1.

Characteristics of the study participants according to amount of leisure-time physical activity.

Variable Men
 Women
Leisure-time physical activity (MET-hours/week)
 P valuea Leisure-time physical activity (MET-hours/week)
 P valuea
0.0 0.1–18.0 18.1–261.9 0.0 0.1–13.4 13.5–83.3
Number of participants 658 403 384 750 347 346
Year of participation
 1996–2000 325 (50.4) 166 (25.7) 154 (23.9) 0.004 370 (55.0) 162 (24.1) 140 (20.8) 0.024
 2001–2005 333 (41.6) 237 (29.6) 230 (28.8) 380 (49.3) 185 (24.0) 206 (26.7)
Working currently
 No 251 (40.8) 159 (25.9) 205 (33.3) <0.001 504 (48.1) 257 (24.6) 285 (27.3) <0.001
 Yes 397 (49.0) 241 (29.7) 173 (21.3) 232 (60.9) 89 (23.4) 60 (15.8)
 Missing 10 (52.6) 3 (15.8) 6 (31.6) 14 (87.5) 1 (6.3) 1 (6.3)
Marital status
 Married 617 (45.1) 385 (28.1) 367 (26.8) 0.58 608 (51.2) 289 (24.3) 291 (24.5) 0.62
 Others 37 (51.4) 18 (25.0) 17 (23.6) 132 (54.6) 56 (23.1) 54 (22.3)
 Missing 4 (100.0) 0 (0.0) 0 (0.0) 10 (76.9) 2 (15.4) 1 (7.7)
Educational attainment
 High school and lower 496 (50.5) 266 (27.1) 221 (22.5) <0.001 639 (52.9) 284 (23.5) 285 (23.6) 0.099
 Junior college and higher 158 (34.6) 136 (29.8) 163 (35.7) 102 (45.1) 63 (27.9) 61 (27.0)
 Missing 4 (80.0) 1 (20.0) 0 (0.0) 9 (100.0) 0 (0.0) 0 (0.0)
Smoking status
 Never 127 (45.0) 88 (31.2) 67 (23.8) <0.001 687 (52.1) 320 (24.2) 313 (23.7) 0.076
 Former 285 (40.7) 196 (28.0) 220 (31.4) 30 (41.7) 17 (23.6) 25 (34.7)
 Current 246 (53.4) 119 (25.8) 96 (20.8) 33 (64.7) 10 (19.6) 8 (15.7)
 Missing 0 (0.0) 0 (0.0) 1 (100.0) 0 (0.0) 0 (0.0) 0 (0.0)
Alcohol consumption
 None 275 (50.6) 135 (24.8) 134 (24.6) 0.015 658 (53.5) 295 (24.0) 276 (22.5) 0.003
 ≤23 g/day (men), current (women) 222 (40.6) 174 (31.8) 151 (27.6) 92 (43.0) 52 (24.3) 70 (32.7)
 23 g/day (men) 161 (45.5) 94 (26.6) 99 (28.0)
Body mass index
 <18.5 39 (61.9) 16 (25.4) 8 (12.7) 0.052 41 (54.7) 19 (25.3) 15 (20.0) 0.79
 18.5 to 24.9 459 (44.3) 290 (28.0) 287 (27.7) 555 (51.2) 261 (24.1) 268 (24.7)
 ≥25.0 160 (46.2) 97 (28.0) 89 (25.7) 154 (54.2) 67 (23.6) 63 (22.1)
Hypertension
 No 317 (43.9) 217 (30.0) 189 (26.1) 0.19 450 (51.1) 212 (24.1) 219 (24.9) 0.58
 Yes 341 (47.3) 186 (25.8) 194 (26.9) 300 (53.4) 135 (24.0) 127 (22.6)
 Missing 0 (0.0) 0 (0.0) 1 (100.0) 0 (0.0) 0 (0.0) 0 (0.0)
Diabetes mellitus
 No 573 (45.9) 361 (28.9) 315 (25.2) 0.010 699 (51.9) 329 (24.4) 318 (23.6) 0.31
 Yes 82 (42.9) 42 (22.0) 67 (35.1) 51 (52.6) 18 (18.6) 28 (28.9)
 Missing 3 (60.0) 0 (0.0) 2 (40.0) 0 (0.0) 0 (0.0) 0 (0.0)
Dyslipidemia
 No 313 (47.7) 171 (26.1) 172 (26.2) 0.24 264 (52.4) 114 (22.6) 126 (25.0) 0.31
 Yes 343 (43.6) 232 (29.5) 211 (26.8) 486 (51.8) 233 (24.8) 219 (23.4)
 Missing 2 (66.7) 0 (0.0) 1 (33.3) 0 (0.0) 0 (0.0) 1 (100.0)
Neuralgia and/or Low back pain
 No 582 (45.1) 367 (28.5) 341 (26.4) 0.72 619 (52.2) 288 (24.3) 278 (23.5) 0.59
 Past 33 (50.8) 15 (23.1) 17 (26.2) 51 (47.2) 22 (20.4) 35 (32.4)
 Current 43 (47.8) 21 (23.3) 26 (28.9) 80 (53.3) 37 (24.7) 33 (22.0)
Geriatric Depression Scale
 ≤5 464 (41.7) 325 (29.2) 325 (29.2) <0.001 502 (47.9) 266 (25.4) 281 (26.8) <0.001
 ≥6 170 (60.5) 66 (43.5) 45 (16.0) 192 (59.8) 71 (22.1) 58 (18.1)
 Missing 24 (48.0) 12 (24.0) 14 (28.0) 56 (76.7) 10 (13.7) 7 (9.6)
Social activity scoreb
 ≤25 (men), ≤27 (women) 234 (52.6) 113 (25.4) 98 (22.0) <0.001 272 (64.2) 75 (17.7) 77 (18.2) <0.001
 26–28 (men), 28–31 (women) 165 (43.0) 123 (32.0) 96 (25.0) 221 (50.6) 111 (25.4) 105 (24.0)
 ≥29 (men), ≥32 (women) 236 (40.9) 163 (28.3) 178 (30.9) 210 (41.7) 144 (28.6) 150 (29.8)
 Missing 23 (59.0) 4 (10.3) 12 (30.8) 47 (60.3) 17 (21.8) 14 (18.0)
Total walking time per day
 <30 min 147 (57.9) 69 (27.2) 38 (15.0) <0.001 78 (63.9) 29 (23.8) 15 (12.3) 0.002
 30 min–1 hour 184 (37.5) 163 (33.2) 144 (29.3) 166 (46.2) 102 (28.4) 91 (25.4)
 1–2 h 143 (38.9) 100 (27.2) 125 (34.0) 204 (49.5) 94 (22.8) 114 (27.7)
 ≥2 h 180 (55.1) 71 (21.7) 76 (23.2) 297 (55.1) 119 (22.1) 123 (22.8)
 Missing 4 (80.0) 0 (0.0) 1 (20.0) 5 (45.5) 3 (27.3) 3 (27.3)
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MET, metabolic equivalent.

a

Characteristics of participants were compared across groups using the chi-squared test of independence.

b

Range: 18–54 points; a higher score indicates more frequent social activity.

Amount of leisure-time physical activity and incidence of disability

In men, the amount of leisure-time physical activity was inversely associated with the incidence of disability (Table 2). Compared with the no activity group, participants reporting 18.1 MET-hours/week or more of activity had a 52% lower risk of support or care levels with dementia (HR 0.48; 95% confidence interval [CI], 0.25–0.94; P for trend = 0.026) in the fully-adjusted model (model 3). Weak inverse associations were also found for support or care levels and for care levels 2–5, but these associations were not statistically significant. In women, no significant associations were found between amount of leisure-time physical activity and incidence of disability (Table 2).

Table 2.

Associations between amount of leisure-time physical activity and incidence of disability.

Men
 Women
Leisure-time physical activity (MET-hours/week) Person-years Number of participants Number of events Model 1a
 Model 2b
 Model 3c
 Leisure-time physical activity (MET-hours/week) Person-years Number of participants Number of events Model 1a
 Model 2b
 Model 3c
HR (95% CI) HR (95% CI) HR (95% CI) HR (95% CI) HR (95% CI) HR (95% CI)
Support or care levels 0.0 6804 658 86 1.00 (reference) 1.00 (reference) 1.00 (reference) 0.0 8004 750 129 1.00 (reference) 1.00 (reference) 1.00 (reference)
0.1–18.0 4157 403 41 0.81 (0.56–1.17) 0.79 (0.54–1.16) 0.84 (0.57–1.25) 0.1–13.4 3747 347 48 0.79 (0.57–1.10) 0.79 (0.56–1.10) 0.87 (0.62–1.22)
18.1–261.9 4046 384 34 0.67 (0.45–1.00) 0.70 (0.46–1.06) 0.68 (0.44–1.06) 13.5–83.3 3611 346 58 1.03 (0.75–1.40) 1.04 (0.76–1.43) 1.06 (0.77–1.48)
P for trend 0.042 0.071 0.084 P for trend 0.90 0.95 0.85
Care levels 2–5 0.0 6957 658 48 1.00 (reference) 1.00 (reference) 1.00 (reference) 0.0 8327 750 51 1.00 (reference) 1.00 (reference) 1.00 (reference)
0.1–18.0 4203 403 24 0.85 (0.52–1.38) 0.86 (0.52–1.42) 0.93 (0.56–1.53) 0.1–13.4 3865 347 16 0.68 (0.39–1.19) 0.69 (0.39–1.22) 0.80 (0.45–1.44)
18.1–261.9 4092 384 15 0.53 (0.30–0.96) 0.54 (0.30–0.99) 0.56 (0.30–1.05) 13.5–83.3 3758 346 18 0.80 (0.47–1.36) 0.85 (0.49–1.47) 0.90 (0.50–1.59)
P for trend 0.036 0.051 0.088 P for trend 0.28 0.40 0.62
Support or care levels with dementia 0.0 6975 658 47 1.00 (reference) 1.00 (reference) 1.00 (reference) 0.0 8357 750 47 1.00 (reference) 1.00 (reference) 1.00 (reference)
0.1–18.0 4210 403 19 0.69 (0.41–1.18) 0.70 (0.40–1.21) 0.72 (0.41–1.27) 0.1–13.4 3888 347 12 0.55 (0.29–1.04) 0.58 (0.30–1.09) 0.62 (0.32–1.19)
18.1–261.9 4107 384 12 0.44 (0.23–0.83) 0.48 (0.25–0.92) 0.48 (0.25–0.94) 13.5–83.3 3751 346 25 1.24 (0.76–2.01) 1.30 (0.79–2.15) 1.37 (0.82–2.31)
P for trend 0.008 0.019 0.026 P for trend 0.66 0.53 0.37
Death 0.0 7104 658 113 1.00 (reference) 1.00 (reference) 1.00 (reference) 0.0 8536 750 45 1.00 (reference) 1.00 (reference) 1.00 (reference)
0.1–18.0 4265 403 59 0.88 (0.64–1.20) 1.01 (0.73–1.39) 1.11 (0.80–1.55) 0.1–13.4 3929 347 21 1.03 (0.61–1.73) 1.04 (0.62–1.74) 1.09 (0.64–1.86)
18.1–261.9 4131 384 44 0.67 (0.48–0.95) 0.79 (0.55–1.14) 0.85 (0.58–1.24) 13.5–83.3 3814 346 25 1.28 (0.79–2.09) 1.29 (0.78–2.13) 1.31 (0.78–2.18)
P for trend 0.027 0.26 0.52 P for trend 0.35 0.34 0.32
Care levels 2–5 or death 0.0 6957 658 141 1.00 (reference) 1.00 (reference) 1.00 (reference) 0.0 8325 750 86 1.00 (reference) 1.00 (reference) 1.00 (reference)
0.1–18.0 4203 403 77 0.91 (0.69–1.20) 1.02 (0.77–1.36) 1.12 (0.84–1.50) 0.1–13.4 3865 347 28 0.70 (0.46–1.08) 0.72 (0.47–1.11) 0.81 (0.52–1.25)
18.1–261.9 4092 384 52 0.63 (0.46–0.86) 0.71 (0.51–0.99) 0.74 (0.52–1.04) 13.5–83.3 3758 346 40 1.05 (0.72–1.53) 1.10 (0.75–1.62) 1.14 (0.77–1.70)
P for trend 0.006 0.071 0.16 P for trend 0.93 0.87 0.66
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CI, confidence interval; HR, hazard ratio; MET, metabolic equivalent.

a

Without adjustment.

b

Model 2 was adjusted for year of participation (continuous variable), currently working (yes or no), marital status (married or other [single, divorced, widowed]), educational attainment (high school and lower or junior college and higher), smoking status (never, former or current), alcohol consumption (men: none, ≤23 g/day or >23 g/day; women: none or current drinkers), and body mass index (<18.5, 18.5–24.9, or ≥25.0).

c

Model 3 was adjusted for the confounding factors in Model 2 and hypertension (yes or no), diabetes mellitus (yes or no), dyslipidemia (yes or no), neuralgia and/or low back pain (no, past, or current), Geriatric Depression Scale (≤5, ≥6, or missing), social activity score (men: ≤25, 26–28, 29–54, or missing; women: ≤27, 28–31, 32–54, or missing), and total walking time per day (<30 min, 30min–1 hour, 1–2 h, or ≥2 h).

Sensitivity analysis

When excluding the incidence of disability or death within 3 years from baseline, the association between amount of leisure-time physical activity and disability onset in men remained nearly the same (support or care levels with dementia: HR for 18.1 MET-hours/week or more 0.49; 95% CI, 0.25–0.97; P for trend = 0.030 [eTable 1]). When excluding respondents who participated in this study through 1999, many events were dropped, which decreased the statistical power. However, most point estimates of HRs for higher activity remained smaller than unity in the analyses for level of leisure-time physical activity in men (eTable 2). Finally, excluding LTCI certification until March 31, 2002 scarcely changed the number of participants and events or the findings (eTable 3).

Discussion

The primary finding from the present study was a significant inverse dose–response relationship between the amount of leisure-time physical activity and the incidence of disability with dementia among young elderly males. This finding may be useful to health care providers in recommending leisure-time physical activity for men.

A previous systematic review recommended any type of physical activity for a duration of 150–180 min/week at a moderate to vigorous intensity, with each session lasting 10 min or longer, in order to help prevent disability among the elderly.40 Japanese guideline recommended engaging in physical activity of 10 MET-hours/week at any intensity for adults 65 years of age or older.43 Nevertheless, these values were estimated using physical activity categories with large variations40 or outcomes other than disability (e.g., incidence of osteoporotic fracture and depression).43 Therefore, the amount of activity appropriate to prevent disability remains unclear. Because of the small number of events in this study, we may not have determined the appropriate amount of physical activity. However, we identified a dose–response relationship between the amount of leisure-time physical activity and the incidence of disability with dementia in men based on quantitative physical activity assessment, so we can say that more leisure-time physical activity is advisable within the range including 18 MET-hours/week (the median in those with leisure-time physical activity).

Contrary to the findings in men, no associations were found between amount of leisure-time physical activity and risk of disability in women. The relatively lower amounts of leisure-time physical activity among females in our study might have attenuated the effect of activity. In fact, the median amount of leisure-time physical activity among the whole population was 4.4 MET-hours/week in men and 0 MET-hours/week in women. A previous study reported that the percentages of days in a week on which light and heavy housework were done were 66.4% and 63.4% in men and 99.5% and 92.1% in women, respectively.56 Although we did not measure physical activity at home, this activity might have more strongly affected the risk of disability in women.

Although physical activity has been shown to be associated with a reduced risk of mortality,57, 58 we did not find such an association in this study. Arrieta et al reported that frequent leisure-time physical activity was associated with a significant risk reduction of all-cause mortality in older adults, but not in middle-aged adults.59 Therefore, the relatively younger age of the participants in the present study may have attenuated the relationship between leisure-time physical activity and mortality.

In the present study, amount of leisure-time physical activity was particularly associated with support or care levels with dementia among men. Recent meta-analyses of cohort studies found that physical activity reduced the risk of cognitive decline60 and Alzheimer's disease.61 The results in the present study corroborate these findings in the young elderly regarding the risk of dementia with long-term care needs. Some underlying mechanisms have been suggested for the protective effects of physical activity against cognitive decline and Alzheimer's disease, including an increased release of neurotrophins; a reduction in cortisol levels; an increased supply of oxygen and nutrients resulting from increased blood flow; improvement of various cardiovascular risk factors, such as hypertension and diabetes mellitus; and a reduction in the risk of cardiovascular and cerebrovascular disease.60

On the other hand, the associations of the amount of physical activity with support or care levels and care levels 2–5 were not significant. Previous studies reported a dose–response relationship between disability regardless of dementia and physical activity as measured using an accelerometer.32, 35 This inconsistency may have resulted from differences in the measurement of physical activity and/or the small number of events in participants engaging in leisure-time physical activity in our study. Because the amount of leisure-time physical activity was marginally associated with disability regardless of dementia, further follow-up and/or larger studies are warranted.

The unique strength of our study is that all the participants were nearly the same age, which allowed us to eliminate confounding by age. In addition, in this study, we comprehensively collected information on demographic, lifestyle, medical, psychological, and social factors. Therefore, we could adjust for potential confounding factors extensively. However, it should be noted that physical activity may have affected the risk of disability through the improvement of medical conditions. In addition, because the duration of follow-up in the present study (median: 11.6 years) was longer than that of previous studies (e.g., 2–9 years6, 7, 8, 9, 10, 11, 12, 13, 15, 16, 21, 23, 24, 25, 27, 29, 31, 32, 34, 35, 37, 38, 39), our results may more accurately reflect the long-term effects of physical activity on the risk of disability.

On the other hand, some limitations should be noted. First, we used a self-report measure to assess leisure-time physical activity. Second, we only assessed leisure-time physical activity at baseline; some participants might have subsequently changed their activity patterns. Third, the LTCI system was launched after the start of the present study. If the LTCI system had started before 2000, those who participated in the study from 1996 to 1999 might have received LTCI certification at that time. However, when we excluded LTCI certification within 2 years from the start of the LTCI system, only a few events were lost (sensitivity analysis, eTable 3), so the results were nearly the same. This suggests that the participants who developed disability and were in poor health before 2000, if any, might not have substantially altered the findings. On the other hand, for persons who participated in the baseline survey through 1999, the follow-up duration was underestimated. Therefore, the associations in this study might have been underestimated. Fourth, only part (25%) of the information regarding non-pre-coded activity types was available. Therefore, we estimated a weighted-average intensity (3.9 METs) of items based on the available data, which could have led to some misclassification in the amount of activity.

In conclusion, the findings in this study showed an inverse dose–response relationship between the amount of leisure-time physical activity and disability with dementia among young elderly men. Therefore, a higher level of physical activity may be advisable to young elderly men in order to prevent disability with dementia.

Financial support

This study was supported by Grants-in-Aid for Scientific Research from the Japanese Ministry of Education, Culture, Sports, Science and Technology (Nos. 15390197, 26460760 and 26520105).

Conflicts of interest

None declared.

Acknowledgments

We greatly appreciate the Nisshin City Healthcare Center and Health and Welfare Department for their cooperation in establishing and following the cohort. We also greatly acknowledge the cooperation of the Nisshin Medical and Dental Associations.

Footnotes

Peer review under responsibility of the Japan Epidemiological Association.

Appendix A

Supplementary data related to this article can be found at http://dx.doi.org/10.1016/j.je.2016.11.004.

Appendix A. Supplementary data

The following is the supplementary data related to this article:

mmc1.pdf (186KB, pdf)

References

  • 1.Global Burden of Disease Study 2013 Collaborators Global, regional, and national incidence, prevalence, and years lived with disability for 301 acute and chronic diseases and injuries in 188 countries, 1990–2013: a systematic analysis for the Global Burden of Disease Study 2013. Lancet. 2015;386:743–800. doi: 10.1016/S0140-6736(15)60692-4. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 2.Health, Labor and Welfare Statistics Association 2014/2015 fiscal year yearly change of long term care insurance related statistics. J Health Welf Stat. 2015;61:1–120. [In Japanese] [Google Scholar]
  • 3.Holmgren M., Lindgren A., de Munter J., Rasmussen F., Ahlström G. Impacts of mobility disability and high and increasing body mass index on health-related quality of life and participation in society: a population-based cohort study from Sweden. BMC Public Health. 2014;14:381. doi: 10.1186/1471-2458-14-381. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 4.Fairhall N., Sherrington C., Cameron I.D. Predicting participation restriction in community-dwelling older men: the concord health and ageing in men project. Age Ageing. 2014;43:31–37. doi: 10.1093/ageing/aft111. [DOI] [PubMed] [Google Scholar]
  • 5.Gaugler J.E., Duval S., Anderson K.A., Kane R.L. Predicting nursing home admission in the U.S: a meta-analysis. BMC Geriatr. 2007;7:13. doi: 10.1186/1471-2318-7-13. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 6.Ward M.M., Hubert H.B., Shi H., Bloch D.A. Physical disability in older runners: prevalence, risk factors, and progression with age. J Gerontol A Biol Sci Med Sci. 1995;50:M70–M77. doi: 10.1093/gerona/50a.2.m70. [DOI] [PubMed] [Google Scholar]
  • 7.Young D.R., Masaki K.H., Curb J.D. Associations of physical activity with performance-based and self-reported physical functioning in older men: the Honolulu Heart Program. J Am Geriatr Soc. 1995;43:845–854. doi: 10.1111/j.1532-5415.1995.tb05525.x. [DOI] [PubMed] [Google Scholar]
  • 8.Wu S.C., Leu S.Y., Li C.Y. Incidence of and predictors for chronic disability in activities of daily living among older people in Taiwan. J Am Geriatr Soc. 1999;47:1082–1086. doi: 10.1111/j.1532-5415.1999.tb05231.x. [DOI] [PubMed] [Google Scholar]
  • 9.Ishizaki T., Watanabe S., Suzuki T., Shibata H., Haga H. Predictors for functional decline among nondisabled older Japanese living in a community during a 3-year follow-up. J Am Geriatr Soc. 2000;48:1424–1429. doi: 10.1111/j.1532-5415.2000.tb02632.x. [DOI] [PubMed] [Google Scholar]
  • 10.Hirvensalo M., Rantanen T., Heikkinen E. Mobility difficulties and physical activity as predictors of mortality and loss of independence in the community-living older population. J Am Geriatr Soc. 2000;48:493–498. doi: 10.1111/j.1532-5415.2000.tb04994.x. [DOI] [PubMed] [Google Scholar]
  • 11.Avlund K., Damsgaard M.T., Sakari-Rantala R., Laukkanen P., Schroll M. Tiredness in daily activities among nondisabled old people as determinant of onset of disability. J Clin Epidemiol. 2002;55:965–973. doi: 10.1016/s0895-4356(02)00463-8. [DOI] [PubMed] [Google Scholar]
  • 12.Østbye T., Taylor D.H., Jung S.H. A longitudinal study of the effects of tobacco smoking and other modifiable risk factors on ill health in middle-aged and old Americans: results from the health and retirement study and asset and health dynamics among the oldest old survey. Prev Med. 2002;34:334–345. doi: 10.1006/pmed.2001.0991. [DOI] [PubMed] [Google Scholar]
  • 13.Stessman J., Hammerman-Rozenberg R., Maaravi Y., Cohen A. Effect of exercise on ease in performing activities of daily living and instrumental activities of daily living from age 70 to 77: the Jerusalem longitudinal study. J Am Geriatr Soc. 2002;50:1934–1938. doi: 10.1046/j.1532-5415.2002.50603.x. [DOI] [PubMed] [Google Scholar]
  • 14.Haveman-Nies A., De Groot L.C., Van Staveren W.A., Survey in Europe on Nutrition and the Elderly: a Concerted Action Study Relation of dietary quality, physical activity, and smoking habits to 10-year changes in health status in older Europeans in the SENECA study. Am J Public Health. 2003;93:318–323. doi: 10.2105/ajph.93.2.318. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 15.Dunlop D.D., Semanik P., Song J., Manheim L.M., Shih V., Chang R.W. Risk factors for functional decline in older adults with arthritis. Arthritis Rheum. 2005;52:1274–1282. doi: 10.1002/art.20968. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 16.Puts M.T., Lips P., Deeg D.J. Static and dynamic measures of frailty predicted decline in performance-based and self-reported physical functioning. J Clin Epidemiol. 2005;58:1188–1198. doi: 10.1016/j.jclinepi.2005.03.008. [DOI] [PubMed] [Google Scholar]
  • 17.Van Den Brink C.L., Picavet H., Van Den Bos G.A., Giampaoli S., Nissinen A., Kromhout D. Duration and intensity of physical activity and disability among European elderly men. Disabil Rehabil. 2005;27:341–347. doi: 10.1080/09638280400018452. [DOI] [PubMed] [Google Scholar]
  • 18.Bäckmand H., Kaprio J., Kujala U.M., Sarna S., Fogelholm M. Physical and psychological functioning of daily living in relation to physical activity. A longitudinal study among former elite male athletes and controls. Aging Clin Exp Res. 2006;18:40–49. doi: 10.1007/BF03324639. [DOI] [PubMed] [Google Scholar]
  • 19.Christensen U., Støvring N., Schultz-Larsen K., Schroll M., Avlund K. Functional ability at age 75: is there an impact of physical inactivity from middle age to early old age? Scand J Med Sci Sports. 2006;16:245–251. doi: 10.1111/j.1600-0838.2005.00459.x. [DOI] [PubMed] [Google Scholar]
  • 20.Berk D.R., Hubert H.B., Fries J.F. Associations of changes in exercise level with subsequent disability among seniors: a 16-year longitudinal study. J Gerontol A Biol Sci Med Sci. 2006;61:97–102. doi: 10.1093/gerona/61.1.97. [DOI] [PubMed] [Google Scholar]
  • 21.Boyle P.A., Buchman A.S., Wilson R.S., Bienias J.L., Bennett D.A. Physical activity is associated with incident disability in community-based older persons. J Am Geriatr Soc. 2007;55:195–201. doi: 10.1111/j.1532-5415.2007.01038.x. [DOI] [PubMed] [Google Scholar]
  • 22.Bruce B., Fries J.F., Hubert H. Regular vigorous physical activity and disability development in healthy overweight and normal-weight seniors: a 13-year study. Am J Public Health. 2008;98:1294–1299. doi: 10.2105/AJPH.2007.119909. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 23.Stessman J., Hammerman-Rozenberg R., Cohen A., Ein-Mor E., Jacobs J.M. Physical activity, function, and longevity among the very old. Arch Intern Med. 2009;169:1476–1483. doi: 10.1001/archinternmed.2009.248. [DOI] [PubMed] [Google Scholar]
  • 24.Hirai H., Kondo K., Ojima T., Murata C. Examination of risk factors for onset of certification of long-term care insurance in community-dwelling older people: AGES project 3-year follow-up study. Nihon Koshu Eisei Zasshi. 2009;56:501–512. [In Japanese] [PubMed] [Google Scholar]
  • 25.Balzi D., Lauretani F., Barchielli A. Risk factors for disability in older persons over 3-year follow-up. Age Ageing. 2010;39:92–98. doi: 10.1093/ageing/afp209. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 26.Lin K.C., Chen P.C., Twisk J.W., Lee H.L., Chi L.Y. Time-varying nature of risk factors for the longitudinal development of disability in older adults with arthritis. J Epidemiol. 2010;20:460–467. doi: 10.2188/jea.JE20090154. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 27.Takeda T., Kondo K., Hirai H. Psychosocial risk factors involved in progressive dementia-associated senility among the elderly residing at home. AGES project-three year cohort longitudinal study. Nihon Koshu Eisei Zasshi. 2010;57:1054–1065. [In Japanese] [PubMed] [Google Scholar]
  • 28.Liao W.C., Li C.R., Lin Y.C. Healthy behaviors and onset of functional disability in older adults: results of a national longitudinal study. J Am Geriatr Soc. 2011;59:200–206. doi: 10.1111/j.1532-5415.2010.03272.x. [DOI] [PubMed] [Google Scholar]
  • 29.Wolinsky F.D., Bentler S.E., Hockenberry J. Long-term declines in ADLs, IADLs, and mobility among older medicare beneficiaries. BMC Geriatr. 2011;11:43. doi: 10.1186/1471-2318-11-43. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 30.Gretebeck R.J., Ferraro K.F., Black D.R., Holland K., Gretebeck K.A. Longitudinal change in physical activity and disability in adults. Am J Health Behav. 2012;36:385–394. doi: 10.5993/AJHB.36.3.9. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 31.Vermeulen J., Spreeuwenberg M.D., Daniëls R., Neyens J.C., Van Rossum E., De Witte L.P. Does a falling level of activity predict disability development in community-dwelling elderly people? Clin Rehabil. 2013;27:546–554. doi: 10.1177/0269215512465209. [DOI] [PubMed] [Google Scholar]
  • 32.Shah R.C., Buchman A.S., Leurgans S., Boyle P.A., Bennett D.A. Association of total daily physical activity with disability in community-dwelling older persons: a prospective cohort study. BMC Geriatr. 2012;12:63. doi: 10.1186/1471-2318-12-63. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 33.Artaud F., Dugravot A., Sabia S., Singh-Manoux A., Tzourio C., Elbaz A. Unhealthy behaviours and disability in older adults: three-City Dijon cohort study. BMJ. 2013;347:f4240. doi: 10.1136/bmj.f4240. [DOI] [PubMed] [Google Scholar]
  • 34.Chou W.T., Tomata Y., Watanabe T., Sugawara Y., Kakizaki M., Tsuji I. Relationships between changes in time spent walking since middle age and incident functional disability. Prev Med. 2014;59:68–72. doi: 10.1016/j.ypmed.2013.11.019. [DOI] [PubMed] [Google Scholar]
  • 35.Dunlop D.D., Song J., Semanik P.A. Relation of physical activity time to incident disability in community dwelling adults with or at risk of knee arthritis: prospective cohort study. BMJ. 2014;348:g2472. doi: 10.1136/bmj.g2472. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 36.Strobl R., Müller M., Thorand B. Men benefit more from midlife leisure-time physical activity than women regarding the development of late-life disability-results of the KORA-Age study. Prev Med. 2014;62:8–13. doi: 10.1016/j.ypmed.2014.01.017. [DOI] [PubMed] [Google Scholar]
  • 37.Konagaya Y., Watanabe T. Evaluation of multimodal factors for the certification of long-term care insurance among community-dwelling elderly: a four-year follow-up study. Nihon Ronen Igakkai Zasshi. 2014;51:170–177. doi: 10.3143/geriatrics.51.170. [In Japanese] [DOI] [PubMed] [Google Scholar]
  • 38.Ku P.W., Fox K.R., Gardiner P.A., Chen L.J. Late-life exercise and difficulty with activities of daily living: an 8-year nationwide follow-up study in Taiwan. Ann Behav Med. 2016;50:237–246. doi: 10.1007/s12160-015-9749-5. [DOI] [PubMed] [Google Scholar]
  • 39.Artaud F., Sabia S., Dugravot A., Kivimaki M., Singh-Manoux A., Elbaz A. Trajectories of unhealthy behaviors in midlife and risk of disability at older ages in the whitehall II cohort study. J Gerontol A Biol Sci Med Sci. 2016;71:1500–1506. doi: 10.1093/gerona/glw060. http://biomedgerontology.oxfordjournals.org/content/early/2016/03/30/gerona.glw060.full.pdf+html [cited 2016 September 8] :[4p]. Available from: [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 40.Paterson D.H., Warburton D.E. Physical activity and functional limitations in older adults: a systematic review related to Canada's physical activity guidelines. Int J Behav Nutr Phys Act. 2010;7:38. doi: 10.1186/1479-5868-7-38. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 41.U.S. Department of Health and Human Services [PDF on the Internet] Physical activity guidelines advisory committee report [cited 2016 September 8]. Available from: http://health.gov/paguidelines/report/pdf/CommitteeReport.pdf.
  • 42.U.S. Department of Health and Human Services [PDF on the Internet]. 2008 physical activity guidelines for Americans [cited 2016 September 8]. Available from: health.gov/paguidelines/pdf/paguide.pdf.
  • 43.Ministry of Health, Labor and Welfare [PDF on the Internet]. Physical activity criteria to promote health 2013 [cited 2016 September 8] [In Japanese]. Available from: http://www.mhlw.go.jp/stf/houdou/2r9852000002xple-att/2r9852000002xpqt.pdf.
  • 44.Hallal P.C., Andersen L.B., Bull F.C., Guthold R., Haskell W., Ekelund U., Lancet Physical Activity Series Working Group Global physical activity levels: surveillance progress, pitfalls, and prospects. Lancet. 2012;380:247–257. doi: 10.1016/S0140-6736(12)60646-1. [DOI] [PubMed] [Google Scholar]
  • 45.Wong E., Stevenson C., Backholer K., Woodward M., Shaw J.E., Peeters A. Predicting the risk of physical disability in old age using modifiable mid-life risk factors. J Epidemiol Community Health. 2015;69:70–76. doi: 10.1136/jech-2014-204456. [DOI] [PubMed] [Google Scholar]
  • 46.Brenner H., Blettner M. Controlling for continuous confounders in epidemiologic research. Epidemiology. 1997;8:429–434. [PubMed] [Google Scholar]
  • 47.Kitamura T., Kawamura T., Tamakoshi A., Wakai K., Ando M., Ohno Y. Rationale, design, and profiles of the New Integrated Suburban Seniority Investigation (NISSIN) Project: a study of an age-specific, community-based cohort of Japanese elderly. J Epidemiol. 2009;19:237–243. doi: 10.2188/jea.JE20081026. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 48.Ainsworth BE, Haskell WL, Herrmann SD, et al, Leon AS [PDF on the Internet]. Healthy Lifestyles Research Center, College of Nursing & Health Innovation, Arizona State University: The Compendium of Physical Activities Tracking Guide [updated 2014 Feb 3; cited 2016 September 8]. Available from: https://docs.google.com/viewer?a=v&pid=sites&srcid=ZGVmYXVsdGRvbWFpbnxjb21wZW5kaXVtb2ZwaHlzaWNhbGFjdGl2aXRpZXN8Z3g6NmNhZWIwM2FjZjhkMzcxMQ.
  • 49.Aoki R., Ohno Y., Tamakoshi A. Lifestyle determinants for social activity levels among the Japanese elderly. Arch Gerontol Geriatr. 1996;22:271–286. doi: 10.1016/0167-4943(96)00699-1. [DOI] [PubMed] [Google Scholar]
  • 50.Kashiwagi A., Kasuga M., Araki E., Committee on the Standardization of Diabetes Mellitus-Related Laboratory Testing of Japan Diabetes Society International clinical harmonization of glycated hemoglobin in Japan: from Japan diabetes society to national glycohemoglobin standardization program values. J Diabetes Investig. 2012;3:39–40. doi: 10.1111/j.2040-1124.2012.00207.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 51.Yesavage J.A. Geriatric depression scale. Psychopharmacol Bull. 1988;24:709–710. [PubMed] [Google Scholar]
  • 52.Yamamoto T., Kondo K., Hirai H., Nakade M., Aida J., Hirata Y. Association between self-reported dental health status and onset of dementia: a 4-year prospective cohort study of older Japanese adults from the Aichi Gerontological Evaluation Study (AGES) Project. Psychosom Med. 2012;74:241–248. doi: 10.1097/PSY.0b013e318246dffb. [DOI] [PubMed] [Google Scholar]
  • 53.Tsutsui T., Muramatsu N. Care-needs certification in the long-term care insurance system of Japan. J Am Geriatr Soc. 2005;53:522–527. doi: 10.1111/j.1532-5415.2005.53175.x. [DOI] [PubMed] [Google Scholar]
  • 54.Ministry of Health, Labor and Welfare [homepage on the Internet]: How to assign care needs level in the long term care insurance system [cited 2016 September 8] [In Japanese]. Available from: http://www.mhlw.go.jp/topics/kaigo/kentou/15kourei/sankou3.html.
  • 55.Chen W., Fukutomi E., Wada T. Comprehensive geriatric functional analysis of elderly populations in four categories of the long-term care insurance system in a rural, depopulated and aging town in Japan. Geriatr Gerontol Int. 2013;13:63–69. doi: 10.1111/j.1447-0594.2012.00859.x. [DOI] [PubMed] [Google Scholar]
  • 56.Hagiwara A., Ito N., Sawai K., Kazuma K. Validity and reliability of the physical activity Scale for the elderly (PASE) in Japanese elderly people. Geriatr Gerontol Int. 2008;8:143–151. doi: 10.1111/j.1447-0594.2008.00463.x. [DOI] [PubMed] [Google Scholar]
  • 57.Moore S.C., Patel A.V., Matthews C.E. Leisure time physical activity of moderate to vigorous intensity and mortality: a large pooled cohort analysis. PLoS Med. 2012;9 doi: 10.1371/journal.pmed.1001335. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 58.Samitz G., Egger M., Zwahlen M. Domains of physical activity and all-cause mortality: systematic review and dose-response meta-analysis of cohort studies. Int J Epidemiol. 2011;40:1382–1400. doi: 10.1093/ije/dyr112. [DOI] [PubMed] [Google Scholar]
  • 59.Arrieta A., Russell L.B. Effects of leisure and non-leisure physical activity on mortality in U.S. adults over two decades. Ann Epidemiol. 2008;18:889–895. doi: 10.1016/j.annepidem.2008.09.007. [DOI] [PubMed] [Google Scholar]
  • 60.Sofi F., Valecchi D., Bacci D. Physical activity and risk of cognitive decline: a meta-analysis of prospective studies. J Intern Med. 2011;269:107–117. doi: 10.1111/j.1365-2796.2010.02281.x. [DOI] [PubMed] [Google Scholar]
  • 61.Beckett M.W., Ardern C.I., Rotondi M.A. A meta-analysis of prospective studies on the role of physical activity and the prevention of Alzheimer's disease in older adults. BMC Geriatr. 2015;15:9. doi: 10.1186/s12877-015-0007-2. [DOI] [PMC free article] [PubMed] [Google Scholar]

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