physical activity ( pa ) has been consistently and positively associated with a range of health benefits for individuals of all ages .
there is a body of evidence showing that people , who are more physically active , have better health outcomes including lower rates of all causes of mortality .
tracking of pa through childhood to adulthood shows substantial drifts between different levels over time .
many factors have been linked to the age - related decline in pa including personal , social , and environmental features .
part of this decline is due to decreased functional fitness ; elderly period is usually associated with decreased muscle mass and strength , agility , flexibility , and maximal aerobic capacity . on the other hand ,
retirement , lacking energy , and listlessness may lead to sedentary lifestyle which make older people more susceptible to chronic diseases that can further affect physical function , and this could lead to a vicious cycle that amplifies negative consequences . demographic , sociocultural , and environmental factors may contribute to declined pa levels among older adults .
higher age , female gender , single or widowed status , higher body mass index ( bmi ) , lower income , lower educational level , and urban residence are demographic factors that have been reported to be associated with low pa in elders .
related personal , sociocultural , and environmental factors include psychosocial stress , time constraint , lack of motivation , lack of family and social support , fear of falling and injury , poor weather , unsafe roads , and unavailability of pa - related facilities .
chronic health conditions can be paradoxically both promoter and barrier to pa of older adults .
diabetes mellitus , high blood pressure , osteoarthritis , low visual acuity , and depression are among the most frequently reported chronic medical conditions .
one view may be that age - related decline in physical activities is a natural process that inevitably occurs sooner or later .
nevertheless , it can not be denied that some elderly people try to maintain high levels of pa in spite of aforementioned barrier factors .
this group may be a minority population in many societies that health systems wish they become a majority .
older people are a highly heterogeneous population with a spectrum of barrier and facilitator factors associated with pa .
the aim of this study was to assess self - reported factors associated with moderate to vigorous pa , as an important health - promoting component of elderly people 's lifestyle , in a sample of iranian older adults .
this is a population - based cross - sectional study carried out in urban community of shiraz , a large city in southern iran , during september and october 2015 .
the sample size was estimated by assuming a 50% prevalence of inadequate moderate to vigorous pa , with a precision of 4% , a confidence level of 95% , and a design effect of 1.5 to account for the cluster design .
shiraz city consists of ten town areas according to municipal divisions . in the first stage ,
then , clusters were numbered , and 17 of them were selected by simple random sampling .
the second stage involved systematically sampling sixty households for interview in each cluster ( main street ) , and the first household of the cluster was selected randomly .
the study team consisted of five interviewers , who were trained by an experienced study coordinator in group sessions .
verbal consent was obtained from each participant after being informed about the aim of the study .
the data collection form included information about participants demographics and pa levels and self - reported barrier and facilitator factors associated with their physical activities .
this study was approved by the school of medicine ethics committee at shiraz university of medical sciences .
data on pa were assessed as the total number of minutes spent weekly doing moderate to vigorous physical activities , and this measure was calculated for every activity separately .
total weekly moderate to vigorous pa was the sum of all activities reported by the participants .
example questions are  how much time do you spend on running activity in a typical day?and  how frequently do you engage in running activity in a week ?  according to the guidelines provided by the world health organization and american college of sports medicine , physical activities are categorized into three levels based on their intensity .
they include light activities ( such as casual walking and light housework ) , moderate activities ( such as brisk walking and recreational swimming ) , and vigorous activities ( such as running and heavy gardening ) .
it is recommended that all older adults engage in at least 150 min / week of moderate intensity or 75 min of vigorous intensity physical activities or an equivalent combination of these . in the present study ,
adequate moderate to vigorous pa was considered as 150 min of moderate activity or 75 min of vigorous activity per week .
the format of questions on barrier and motivator factors of pa was in such a way that respondents answered yes or no .
example question is  which of the following items is a barrier to your regular pa ?  with regard to medical barriers , the participants were asked whether they suffered from any chronic condition mentioned in the form .
an example question is  do you suffer from a chronic knee pain ?  the participants answered yes or no .
in addition to descriptive statistics , chi - square test was used to assess bivariate association between adequacy of pa level and study variables , including demographics and self - reported barrier and facilitator factors . the independent variables with a level of significance of p < 0.10 in the bivariate analysis were included in final regression model .
it has been recommended to use prevalence ratios instead of odds ratios in cross - sectional studies with binary outcomes when the outcome is not rare .
therefore , we estimated prevalence ratios of self - reported factors using log - binomial regression analysis , the preferred method which yields less biased estimates with higher power and smaller standard errors .
data were statistically analyzed using spss software , version 23 ( spss ibm , new york , usa ) .
this is a population - based cross - sectional study carried out in urban community of shiraz , a large city in southern iran , during september and october 2015 .
the sample size was estimated by assuming a 50% prevalence of inadequate moderate to vigorous pa , with a precision of 4% , a confidence level of 95% , and a design effect of 1.5 to account for the cluster design .
shiraz city consists of ten town areas according to municipal divisions . in the first stage ,
then , clusters were numbered , and 17 of them were selected by simple random sampling .
the second stage involved systematically sampling sixty households for interview in each cluster ( main street ) , and the first household of the cluster was selected randomly .
the study team consisted of five interviewers , who were trained by an experienced study coordinator in group sessions .
verbal consent was obtained from each participant after being informed about the aim of the study .
the data collection form included information about participants demographics and pa levels and self - reported barrier and facilitator factors associated with their physical activities .
this study was approved by the school of medicine ethics committee at shiraz university of medical sciences .
data on pa were assessed as the total number of minutes spent weekly doing moderate to vigorous physical activities , and this measure was calculated for every activity separately .
total weekly moderate to vigorous pa was the sum of all activities reported by the participants .
example questions are  how much time do you spend on running activity in a typical day?and  how frequently do you engage in running activity in a week ?  according to the guidelines provided by the world health organization and american college of sports medicine , physical activities are categorized into three levels based on their intensity .
they include light activities ( such as casual walking and light housework ) , moderate activities ( such as brisk walking and recreational swimming ) , and vigorous activities ( such as running and heavy gardening ) .
it is recommended that all older adults engage in at least 150 min / week of moderate intensity or 75 min of vigorous intensity physical activities or an equivalent combination of these . in the present study ,
adequate moderate to vigorous pa was considered as 150 min of moderate activity or 75 min of vigorous activity per week .
the format of questions on barrier and motivator factors of pa was in such a way that respondents answered yes or no .
example question is  which of the following items is a barrier to your regular pa ?  with regard to medical barriers , the participants were asked whether they suffered from any chronic condition mentioned in the form .
an example question is  do you suffer from a chronic knee pain ?  the participants answered yes or no .
in addition to descriptive statistics , chi - square test was used to assess bivariate association between adequacy of pa level and study variables , including demographics and self - reported barrier and facilitator factors . the independent variables with a level of significance of p < 0.10 in the bivariate analysis were included in final regression model .
it has been recommended to use prevalence ratios instead of odds ratios in cross - sectional studies with binary outcomes when the outcome is not rare .
therefore , we estimated prevalence ratios of self - reported factors using log - binomial regression analysis , the preferred method which yields less biased estimates with higher power and smaller standard errors .
data were statistically analyzed using spss software , version 23 ( spss ibm , new york , usa ) .
participants were elderly community dwellers living in urban areas in shiraz , aged 6080 years ( mean = 68.5 , standard deviation = 6.3 ) .
only 13 people refused to participate in the study ( response rate : 98.7% ) .
almost 69.9% were married , 24.8% were widowed , and 5.3% were single or divorced . the majority ( 79.7% ) of participants
many of participants ( 68% ) were illiterate or primary school educated and just 14% were college graduates . with regard to smoking status ,
18.8% were current smokers ( defined as having smoked in the past month ) , 13.2% were ex - smokers ( defined as no smoking for at least 1 month ) , and 68% were never smokers .
only 10.5% of study population had adequate moderate to vigorous pa ( defined as at least 150 min moderate pa or equivalent amounts of vigorous activity per week ) .
there was no statistically significant association between outcome variable and bmi ( p = 0.12 ) and smoking status ( p = 0.89 ) .
other demographic factors including sex , age , educational level , job , and marital status were associated with outcome , especially educational attainment ( p < 0.001 ) [ table 1 ] .
demographic and physical activity level characteristics of a sample of 1000 iranian elderly people bivariate analysis between activity level and medical factors has been presented in table 2 .
lower extremity pain was significantly associated with moderate to vigorous pa ( p < 0.001 ) . visual impairment ( p = 0.14 ) ,
history of diabetes mellitus ( p = 0.08 ) , chronic lung disease ( p = 0.36 ) , angina pectoris ( p = 1 ) , and history of mental disorders ( p = 0.4 ) were not significantly associated with pa levels .
bivariate associations of physical activity level with medical barriers among psychosocial and environmental features , daily life problems ( p < 0.001 ) , lack of motivation ( p = 0.001 ) , fear of falling ( p = 0.006 ) , fear of injury ( p = 0.01 ) , unsafe roads ( p = 0.04 ) , and positive effect on mood ( p = 0.005 ) were the most related factors [ table 3 ] .
bivariate associations of physical activity level with psychosocial and environmental factors many of demographics , except educational level , had no significant association with outcome in final regression model .
significant factors that predicted inadequate moderate to vigorous pa levels among iranian older people in log - binomial regression analysis were lack of motivation ( p = 0.005 ) and daily life problems ( p = 0.001 ) . educational level ( p = 0.019 ) and chronic knee pain ( p = 0.018 ) were the most important demographic factor and medical barrier , respectively [ table 4 ] .
adjusted prevalence ratios of statistically significant factors associated with inadequate moderate to vigorous physical activity among iranian elderly people
our study demonstrates that a significant proportion of iranian older adults ( about 90% ) do not engage in adequate moderate to vigorous pa .
numerous studies have shown that less than half of older adults have adequate pa levels .
a report from south korea shows that 80% of elders aged 6070 years and 90% of elders aged 70 and over do not engage in moderate pa .
another study reported that < 20% of usa adults older than 64 years engage in the recommended amount of pa .
other reports from australia and brazil showed that 50% and 80% of older adults have adequate pa , respectively .
diverse reported levels of pa among older people of different countries are probably due to different study methods , reference guidelines used , the age range considered , and actual differences related to sociocultural factors . in the present study , the highest prevalence of adequate moderate to vigorous pa was among the higher educated participants ( 17.6% ) which comprised about one third of the whole study population , and the lowest prevalence was among lower educated participants ( 7.2% ) .
pa of elders aged 7180 was lower than those aged 6070 , and female participants had lower pa levels than male participants .
this is similar to the previous studies that reported decreased pa with age and lower levels in women compared with men .
we found no association between bmi and moderate to vigorous pa levels in older adults , a result similar to the study carried out by vagetti et al . among brazilian older women .
in contrast , findings of the study by jenkins and fultz showed an association between bmi and pa of older adults .
findings of other studies suggest that effect of retirement on pa level of older adults is not consistent and depends on some other factors .
retirement from a manual work , for example , may result in loss of job - related physical activities , yet it can also increase leisure time pa . in the present study , the most important health - related barriers to pa were lower extremity joint pain and high blood pressure . in most previous studies ,
few studies have specifically focused on health - related barrier factors associated with activity of older adults including diabetes mellitus , knee pain , and low vision .
vagetti et al . suggested that high blood pressure may have a positive association with higher level of pa in older adults , but this finding has not been supported by other studies .
pa may be viewed as a voluntary behavior which can be affected by physical , psychosocial , and environmental determinants .
the ultimate outcome may be determined by the weights of different factors and interactions between them . in our study , we used log - binomial regression model to determine the most important factors associated with more than light pa among this target group .
our findings suggest that psychosocial attributes are important determinants of engagement in moderate to vigorous physical activities among iranian elderly population .
some other studies have also reported psychosocial attributes as important factors that influence elderly people 's pa .
indeed , factors such as lack of interest , unwillingness , time constraints , and daily life problems may be interrelated and actually reflect the same thing that is lack of motivation .
it may be explained by the assumption that obtaining this level of activity is more difficult than light activities and requires more motivation .
as some other studies , we found educational attainment as a notable demographic factor related to pa levels in older adults .
this factor may influence people 's self - efficacy and indirectly affects motivation to perform different tasks such as regular pa .
it seems that older adult 's pa is a multifactorial behavior with a wide range of interrelated factors playing a role in determining individual activity levels .
hence , it is not surprising that studies of pa levels of older adults from different parts of the world identified different factors as notable determinants ; considering this issue from a global perspective , pa behaviors of elderly people may seem to be fairly unpredictable .
therefore , it may be prudent to identify the most important related factors in every society and prioritize interventions accordingly . maintaining
an optimal pa level by some of older adults shows that sedentary lifestyle is not an inevitable outcome of aging at least for young elders
. one important limitation of our study is that , due to the cross - sectional design , temporality of exposures and outcome can not be determined .
some studies have shown that self - reported measures can be both higher and lower than directly measured pa by pedometer . similarly , self - reported medical conditions could not be documented with medical procedures .
we did not evaluate people more than 80 years of age because pa decline tends to be most dramatic in the oldest old , and moderate to vigorous level of activity is probably rare in this age group .
interventions to promote pa of older adults should be multilevel and particularly targeting personal psychosocial factors .
this project was financially supported by the vice chancellor for research and technology , shiraz university of medical sciences , shiraz , iran .
this project was financially supported by the vice chancellor for research and technology , shiraz university of medical sciences , shiraz , iran .
 background : physical activity ( pa ) typically decreases with aging , especially of moderate to vigorous level , and this change affects health outcomes of older adults . 
 age - related decline is not evenly distributed across elderly population and is attributed to psychosocial , physical , and environmental determinants.methods:we selected a sample of 1000 elderly people from urban parts of shiraz in southern iran with a two - stage random sampling procedure . 
 self - reported pa data and correlates of moderate to vigorous activity were collected by interview with the respondents from selected households . 
 bivariate associations were examined using chi - square test . 
 log - binomial regression was used to weigh variables associated with more than light pa.results:some demographic variables ( older age , female sex , lower education level , retirement , and single or widowed status ) , health problems ( lower extremity pain and hypertension ) , and psychosocial factors ( lack of motivation , fear of injury , unsafe roads , and daily life problems ) were potential correlates of inadequate pa with bivariate analysis . in log - binomial regression model , 
 lack of motivation ( adjusted prevalence ratio [ apr ] = 2.11 , 95% confidence interval [ ci ] : 1.253.56 ) , daily life problems ( apr = 1.82 , 95% ci : 1.262.62 ) , lower educational level ( apr = 1.64 , 95% ci : 1.082.49 ) , unsafe roads ( apr = 1.59 , 95% ci : 1.022.49 ) , and knee pain ( apr = 1.68 , 95% ci : 1.092.58 ) were associated with lower engagement in moderate to vigorous pa among iranian older adults.conclusions:psychosocial attributes considerably influence pa behaviors in older adults . 
 lower extremity joint pain is a key medical concern . 
 interventions to promote pa among older adults should be multilevel and particularly targeting personal psychosocial factors . 
Introduction
Methods
Study design and participants
Study instrument
Statistical analysis
Results
Discussion
Conclusions
Financial support and sponsorship
Conflicts of interest