Association of Disease-Specific Mortality with Fitness Measurements and Nonparticipation in an 80-Year-Old Population

A lower level of physical fitness and activity is known to be associated with a shorter survival rate in community-dwelling populations of adults and elderly (Blair et al., 2001; Erlichman et al., 2002; Rantanen, 2003; Mitnitski et al., 2005). Subjects’ cardiorespiratory fitness level based on a cycle ergometer or treadmill was predictive of total mortality (Kampert et al., 1996; Bodegard et al., 2005; Park et al., 2009), fatal cardiac event (Laukkanen et al., 2004; Bodegard et al., 2005), or cancer mortality (Evenson et al., 2003) in adult persons. Leisure time activity and walking pace were also inversely associated with all-cause mortality and mortalities due to coronary heart disease, cardiovascular disease, respiratory disease, and cancers in middle-aged men (Kampert et al., 1996; Simith et al., 2000; Lam et al., 2004; Batty et al., 2010).


Introduction
A lower level of physical fitness and activity is known to be associated with a shorter survival rate in community-dwelling populations of adults and elderly (Blair et al., 2001;Erlichman et al., 2002;Rantanen, 2003;Mitnitski et al., 2005).Subjects' cardiorespiratory fitness level based on a cycle ergometer or treadmill was predictive of total mortality (Kampert et al., 1996;Bodegard et al., 2005;Park et al., 2009), fatal cardiac event (Laukkanen et al., 2004;Bodegard et al., 2005), or cancer mortality (Evenson et al., 2003) in adult persons.Leisure time activity and walking pace were also inversely associated with all-cause mortality and mortalities due to coronary heart disease, cardiovascular disease, respiratory disease, and cancers in middle-aged men (Kampert et al., 1996;Simith et al., 2000;Lam et al., 2004;Batty et al., 2010).
In an elderly population of 75-year-olds, poor physical activity was a predictor of mortality in women but not in men (Era and Rantanen, 1997).Increasing and maintaining physical activity could lengthen life for older women aged between 65 and 75 years (Gregg et al., 2003).Physical fitness as measured by the stepping rate of legs was also inversely related to all-cause 4-year mortality in an 80-year-old population (Takata et al., 2007).In an elderly population, poor muscle strength is related to increased mortality.Lowest tertiles of 75-and 80-year-old individuals for strength of handgrip, elbow flexion, knee extension, trunk extension, and trunk flexion had a higher total mortality than that of individuals in the highest tertiles (Portegijs et al., 2007).Handgrip strength was a predictor of all-cause mortality in the oldest elderly population (Ling et al., 2010), persons aged 65 and over (Gale et al., 2007), and persons aged 70-79 years (Newman et al., 2006).
As mentioned above, although a lower level of physical activity, physical fitness, or muscle strength is likely to be associated with a higher total mortality in an elderly population, the on the plate as rapidly as possible until the legs were fully extended.The body mass of the subject was applied as resistance.The best score from five trials was used for statistical analysis.
All data are reported as means ± SD.Differences in mean values between groups were assessed by analysis of variance.Categorical variables were compared using the χ 2 test.Associations between physical fitness and time to 12-year mortality were assessed using the multivariate Cox proportional hazards regression model.Gender, smoking, body mass index (BMI), and levels of total serum cholesterol and glucose were fitted as continuous variables.Comparisons of the survival rates among groups according to physical fitness measurements and participation in tests were assessed by the method of Kaplan and Meier, followed by a log-rank test to assess the significance between survival curves.All statistical analyses were performed using SPSS 16.0 (SPSS Japan, Inc., Tokyo, Japan).Results were considered statistically significant when P had a value below 0.05.
Basal characteristics at the start of study in individuals at age of 80-year who died or did not die during the following 12-year are shown in Table 1.BMI and serum level of total cholesterol were lower in non-survivors than in survivors, while serum level of glucose was higher in the former than in the latter.Systolic blood pressure (SBP) did not differ between individuals who were alive and those who died during the follow-up period.Men and smokers were more prevalent in the non-survivor than in the survivor group, whereas no difference was found in the percent of alcohol drinkers or the percent who suffered complications between the non-survivors and the survivors.2A) or women (Table 2B) who were alive and those who died from all causes, cardiovascular disease, respiratory disease, cancer, or senility during the 12-year follow-up period.Scores of handgrip strength, one-leg standing, leg extension strength of a single leg, leg extension strength of both legs, and leg extension power were higher in men who survived than in those in the all-cause mortality group, while scores of stepping rate of legs were not different.Scores for handgrip strength, leg extension strength of a single leg, leg extension strength of both legs, and leg extension power were higher in men who did not die due to respiratory disease than in those who died due to respiratory disease.Men who did not die due to senility also had a higher score of one-leg standing time than that of men who died due to senility.Similarly, in women, scores for handgrip strength, leg extension strength of a single leg, leg extension strength of both legs, stepping rate of legs, and leg extension power were higher in survivors than in non-survivors.Scores for stepping rate were slightly higher in women who did not die due to cardiovascular disease than in women who died due to cardiovascular disease.Women who did not die from respiratory disease had a higher score for leg extension power than that of women who died from respiratory disease.Women who died from cancer had a slightly higher score of leg extension strength of a single leg than that of women who did not die from cancer.Scores for handgrip strength, leg extension strength of a single leg, leg extension strength of both legs, and leg extension power were higher in women who did not die due to senility than in women who died due to senility.Overall survival curves obtained by the Kaplan-Meier method during the 12-year follow-up period in men and women who had a higher score, lower score, or did not participate in physical fitness tests such as handgrip strength (Fig. 1A), one-leg standing (Fig. 1B), leg extension strength of a single leg (Fig. 1C), leg extension strength of both legs (Fig. 1D), stepping rate of legs (Fig. 1E), and leg extension power (Fig. 1F) are shown in Figure 1.Table 3A shows the χ 2 and P with the log rank test by the Kaplan-Meier method for comparisons of the overall survival curves among groups.Men and women who had a high score on the handgrip strength test survived longer than those with a low score.Women with a high score on the handgrip test also survived longer than women who did not participate in this test (Fig 1A, Table 3A).The survival rate in the group with a high score on the one-leg standing test was better than that in men or women nonparticipants.Women with a low score on the one-leg standing time test also had a better survival rate than that of those who did not participate in this fitness test (Fig. 1B, Table 3A).Men and women with high scores for leg extension strength of a single leg, leg extension strength of both legs, or leg extension power had a better survival rate than that of those with low scores on these tests or that of those who did not participate in these tests.Men with low scores for leg extension strength of both legs also survived slightly longer than nonparticipants (Figs.1C, 1D, 1F, Table 3A).
Men or women with high scores for stepping rate had a better survival rate than those who did not participate in this test.Women with a high score for stepping rate also had a better survival rate than that of those with a low score (Fig. 1E, Table 3A).
Survival rates for men who did not die from cardiovascular diseases were better in those with a high score on the leg extension strength test of both legs and on the stepping rate test of legs than for those who did not participate in these fitness tests.Men with cardiovascular disease and with a low score on the leg extension strength test of a single leg or both legs also had a better survival rate than that of nonparticipants.Women with high score on stepping rate test also did not die from cardiovascular diseases as compared to women with low score on this test (Table 3B).
Survival curves in men and women who did not die due to respiratory disease also were compared among individuals with a high score, a low score, or nonparticipation for various fitness tests.Men and women with high score on leg extension power test had better survival rate from respiratory disease than those with low score or nonparticipation on this test.Men with low score on the leg extension power test also had a better survival rate than that of nonparticipants.Men with high score on leg extension strength test of single leg and leg extension strength test of both legs had longer survival curves from respiratory disease than men with low score or without participation on these fitness tests.Longer survival curves from respiratory disease were found in men with a high score on the handgrip test than in those with a low score.Similarly, men with a high score on the one-leg standing time test or the stepping rate test survived longer than nonparticipants.Men with a low score on the stepping rate test also survived longer than men who were nonparticipants (Table 3C).
Survival curves in men and women, who did not die from cancer, were not different among individuals with high score, low score, and nonparticipation for each fitness test (Table 3D).
Men with low score for leg extension strength test of double legs or stepping rate test of leg died from senility fewer than nonparticipants.Survival rate in men who did not die from senility were longer in those with high score for leg extension power test than in those without participation.A better survival rate was found in women with high score for ), lower score ( ), or did not participate ( ) in physical fitness tests such as handgrip strength (Fig. 1A), one-leg standing (Fig. 1B), leg extension strength of a single leg (Fig. 1C), leg extension strength of both legs (Fig. 1D), stepping rate of legs (Fig. 1E), and leg extension power (Fig. 1F) .
handgrip strength test, leg extension strength test of single leg, leg extension strength test of double legs, or leg extension power test than in those with low score or nonparticipation for test.Women with a high score on the one-leg standing test also had a better survival rate than that of nonparticipants (Table 3E).

Men
Women Table 3. χ 2 value and P value with the log rank test by the Kaplan-Meier method for comparisons of the survival curves among groups in men or women who had a high score, a low score, or nonparticipation in physical fitness tests during the 12-year follow-up period in subjects who did not die due to any cause (A), cardiovascular diseases (B), respiratory disease (C), cancer (D), or senility (E).
Survival curves were also compared between participants and nonparticipants.Men who participated survived longer than nonparticipants in the case of the fitness tests of single or double leg extension strength, stepping rate of legs, or leg extension power, while women who participated survived longer than nonparticipants in the case of the fitness tests for one-leg standing time, single or double leg extension strength, stepping rate of legs, or leg extension power (Table 4A).Cardiovascular deaths were more prevalent in men who did not participate than in men who participated in fitness tests of single or double leg extension strength or stepping rate of legs, while no difference in cardiovascular deaths was found between women who participated and those who did not participate in any fitness test (Table 4B).Similarly, mortality due respiratory disease was more prevalent for nonparticipating men than for participating men in the case of the fitness tests of one-leg standing time, single or double leg extension strength, stepping rate of legs, or leg extension power, while there was no difference in respiratory mortality between women who participated and those who did not participate in any fitness test (Table 4C).No difference was found in cancer mortality between nonparticipants and participants in men or women (Table 4D).Mortality due to senility was higher in women who did not participate in the handgrip strength test, single or double leg extension strength test, stepping rate test of legs, and leg extension power test, whereas senility mortality was more prevalent in nonparticipating men for tests of single or double leg extension strength, stepping rate of legs, or leg extension power (Table 4E).Table 4. χ 2 value and P value with the log rank test by the Kaplan-Meier method for comparisons of the survival curves among groups in men or women who participated or did not participate in physical fitness tests during the 12-year follow-up period in subjects who did not die due to any cause (A), cardiovascular diseases (B), respiratory disease (C), cancer (D), or senility (E).

Men
Associations between physical fitness measurements and mortalities due to all causes, cardiovascular diseases, respiratory diseases, cancers, or senility were assessed by multivariate Cox regression analyses adjusted for gender, serum level of total cholesterol and glucose, BMI, and smoking, being performed to calculate the risk for mortality associated with a 1 kg, 1 s, 1 step/10 s, 1 W increase (continuous analysis) in each fitness measurement (Table 5).Since all subjects were 80 years old at the start of the study, age was not included as a confounding factor in these analyses.All-cause mortality adjusted for various confounding factors fell 0.2% with 1 W increase in leg extension power.Similarly, total mortality decreased by 1-2% with 1 kg increase in single or double leg extension strength.A decrease in all-cause mortality by 3% was also found with 1 kg increase in handgrip strength.A 1% fall in all-cause mortality was found with an increase of 1 s in oneleg standing time or an increase of 1 step/10 s in stepping rate (Table 5A).Mortality due to cardiovascular diseases was decreased by 2% with a 1 step/10 s increase in stepping rate, while the mortality rate was not associated with the other fitness measurements (Table 5B).There were associations between muscle strength of leg extension or handgrip and mortality due to respiratory diseases.A 3-4% decrease in mortality due to respiratory diseases was found with a 1 kg increase in single or double leg extension strength.Similarly, mortality due to respiratory diseases was decreased by 0.3% with a 1 W increase in leg extension power.A 1 kg increase in handgrip strength was also associated with a 6% fall in mortality from respiratory diseases (Table 5C).No associations were found between mortality from cancers and physical fitness measurements (Table 5D).Mortality due to senility was associated with muscle strength.A 5-6% fall in mortality from senility was found with a 1 kg increase in single or double leg extension strength.Similarly, a 0.3% fall in mortality from senility was found with a 1 W increase in leg extension power.A 1 kg increase in handgrip strength was associated with a 9% decrease in mortality due to senility (Table 5E).Poor muscle strength has been reported to be independently associated with mortality risk in healthy middle-aged men (Rantanen et al., 2000;Rantanen, 2003;Metter et al., 2004), people aged 20-69 years (Katzmarzyk et al., 2002), and elderly people (Era and Rantanen, 1997;Gale et al., 2006;Newman et al., 2006a;Portegijs et al., 2007;Takata et al., 2007;Ling et al., 2010).After adjusting for confounders, a significant elevation in all-cause mortality was found in the lowest tertile of handgrip strength at age 85 years, and in the lowest two tertiles of handgrip strength at age 89 years (65.0%women; Ling et al., 2010).Both handgrip strength and knee extension strength (51.6% women) were strongly related to all-cause mortality in participants aged 70-79 years (Newman et al., 2006).Similarly, the lowest tertile of handgrip, elbow flexion, knee extension, trunk extension, and trunk flexion was related to approximately twofold higher mortality from all causes in community-dwelling 75-and 80year-old people (67.2% women; Portegijs et al., 2007).Poorer grip strength was associated with increased mortality from not only all causes but also from cardiovascular disease and from cancer in men aged 65 and over (Gale et al., 2006), while this association was not found in women.We also previously found an association between pneumonia mortality and leg extension strength of a single leg in an 80-year-old population with a 4-year follow-up period (Takata et al., 2007).The present findings that mortality due to respiratory disease or senility was higher in elderly with poor muscle strength of leg extension or handgrip indicate a new association between disease-specific mortality and muscle strength.Since there have been only a few investigations of the elderly with regard to the association between disease-specific mortality and muscle strength, further investigations are needed.

Physical fitness measurement
In studies of middle-aged populations, there have been several reports indicating an association in disease-specific mortality with physical activity or physical fitness.Blair and his coworkers (2001) summarized results from 67 articles and found greater longevity and reduced risk of coronary heart disease, cardiovascular disease, stroke, and colon cancer in more active individuals.They also found that men aged 20 to 82 years who maintained adequate fitness or improved their physical fitness were less likely to die from all causes and from cardiovascular disease than persistently unfit men (1995).An inverse association between exercise frequency and mortality in adults aged 35 years and over was stronger for cardiovascular than cancer deaths and was strongest in the case of respiratory mortality (Lam et al., 2004).Leisure time activity was inversely related to all-cause, cardiovascular, coronary heart disease, and noncardiovascular mortality among men aged 40 to 64 years (Batty et al., 2003).Walking pace was inversely related to mortality due to all causes, coronary heart disease, and total cancer in males aged 40 to 69 years (Batty et al., 2010).Similarly, a strong inverse association was found in individuals with an average age of 43 years between all-cause mortality and level of physical fitness in both men and women.The risk of mortality from cancer declined with increasing levels of fitness or physical activity among men, but not among women with an average age of 43 years (Kampert et al., 1996).Walking pace in men aged 40 to 64 years demonstrated inverse relations with mortality from all causes, coronary heart disease, other cardiovascular disease, all cancers, respiratory www.intechopen.comAssociation of Disease-Specific Mortality with Fitness Measurements and Nonparticipation in an 80-Year-Old Population 79 disease, colorectal cancer, and hematopoietic cancer with adjustment for confounding factors (Smith et al., 2000).Adjusted cancer mortality was lower in the most fit quintile relative to the other four quintiles for men but not for women with an average age of 46 years (Evenson et al., 2003).Peak exercise oxygen consumption with a cycle ergometer exercise test in men aged 42 to 60 years was predictive of non-fatal and fatal cardiac events among men with and without risk factors (Laukkanen et al., 2004).Both regular physical activity and a high level of fitness in middle-aged men were inversely related to all-cause, cancer, and cardiovascular mortalities (Park et al, 2009).
In a similar fashion to the middle-aged population, there are studies indicating an association between poor physical activity and disease-specific mortality in the elderly population, though there are fewer studies investigating an association between diseasespecific mortality and physical fitness level of the elderly population.Women aged 65 years or over with increased walking and physical activity had lower mortality from all causes, cardiovascular disease, and cancer (Gregg et al., 2003).Inability to complete walking 400 m in participants aged 70 to 79 years was associated with a higher risk of total mortality and incident cardiovascular disease (Newman et al., 2006b).
Nonparticipation in regular exercise was associated with high mortality due to all causes and cardiovascular disease, but not cancers among women aged 40 to 70 years (Nechuta et al., 2010).In a population-based survey for 54,372 Finnish people aged 25 to 64 years, nonparticipant men had twice and nonparticipant women had 2.5-fold higher all-cause mortality than the participating men and women.Nonparticipants had also significantly higher cause-specific mortalities due to cardiovascular disease and violence, whereas no difference was found in mortality due to cancer between participants and nonparticipants (Jousilahti et al., 2005).Annual mortality among nonparticipants was twice that of the participants during a follow-up period of 11.8 years in that study.Coronary death was significantly more common among nonparticipants (Rosengren et al., 1987).In very elderly persons older than 90 years, nonparticipants for follow-up study had lower levels of physical activity and leisure activity (Fernandez-Ballesteros et al., 2010), suggesting that nonparticipants are likely to have a worse survival rate than participants.These investigations all suggest that all-cause and cardiovascular disease mortality seems higher in nonparticipants than in participants during long-term surveys or in regular exercise program.However, little is known about an association in mortality with nonparticipation in fitness tests in an elderly population.We found in the present study that 80-year-old subjects who were nonparticipants in physical fitness tests were partly associated with higher mortality from all causes, cardiovascular disease, respiratory disease, and senility as compared to participants, while no association was found between nonparticipation and cancer mortality.
A limitation of the present study is that the sample size was relatively small.Since the subject age was limited to 80 years, the association between physical fitness and mortality in very elderly individuals older than 80 years should be evaluated in a future study.It is also possible that residual confounding factors other than gender, serum level of total cholesterol and glucose, BMI, and smoking could influence the findings.However, the present findings clearly suggest that physical fitness measurements and nonparticipation in tests predict allcause and disease-specific mortality at the age of 80 in community-dwelling adults. www.intechopen.com

Conclusion
In the present study, lower fitness levels for various muscle strength tests were found to be associated with increases in not only all-cause mortality but also disease-specific mortality in an 80-year-old community-dwelling population.Nonparticipation in fitness tests was also associated with increased mortalities.These findings suggest that very elderly persons could survive longer by elevating their level of physical fitness and muscle strength.Intervention study in a very elderly population is needed to clarify the effect of fitness on longevity.
Fig. 1.Overall survival curve during the 12-year follow-up period in men and women who had a higher score (), lower score ( ), or did not participate ( ) in physical fitness tests such as handgrip strength (Fig.1A), one-leg standing (Fig.1B), leg extension strength of a single leg (Fig.1C), leg extension strength of both legs (Fig.1D), stepping rate of legs (Fig.1E), and leg extension power (Fig.1F) .

Table 1
. Basal characteristics at the start of study in individuals at age of 80-year-old who die or did not die during the following 12-year period.*P<0.05,**P<0.01,***P<0.001At the start of the study, when all participants were 80 years old, 642, 551, 555, 556, 567, and 547 individuals completed the handgrip strength test, one-leg standing test, leg extension strength test of a single leg, leg extension strength test of both legs, stepping rate test of legs, and leg extension power test, respectively.Scores for each physical fitness test were compared between men (Table

Table 2 .
Physical fitness measurements at the start of the study in 80-year-old men (A) and women (B) who died or did not die due to all causes, cardiovascular disease, respiratory disease, cancer, or senility, during the 12-year follow-up period.. *P<0.05,**P<0.01, ***P<0.001www.intechopen.com . Comparisons among survival curves during the 12-year follow-up period in men or women who did not die from senility, and had a high score, low score, or nonparticipation in the physical fitness tests listed. E Comparisons among survival curves during the 12-year follow-up period in men or women who did not die from cancer, between participants who had a high score and nonparticipants in the physical fitness tests listed.
B. Comparisons among survival curves during the 12-year follow-up period in men or women who did not die from cardiovascular disease, between participants and nonparticipants in the physical fitness tests listed.