research has previously demonstrated an inverse association between smoking status and physical activity ( pa ) .
less research , however , has examined the specific association between nicotine dependence and pa , which is worth considering as individuals with greater nicotine dependence often have worse health outcomes ( e.g. , depression ) .
to our knowledge , few studies have examined the association between nicotine dependence and pa .
each of these studies showed an inverse association between nicotine dependence and pa , suggesting that smokers with greater nicotine dependence engage in less pa and more sedentary behavior than their counterparts with less nicotine dependence . a limitation of these studies , however , was their exclusive use of self - report pa , which is prone to considerable measurement error .
validation studies examining the association between self - report pa and some gold - standard ( e.g. , accelerometry , indirect calorimetry , and doubly labeled water ) typically show a poor correlation in the range of 0.3 - 0.5 .
validated , self - report questionnaires only account for 9 - 25% of the variance in the outcome parameter , and are therefore likely to result in considerable misclassification .
based on this gap in the literature , the purpose of this study was to examine the association between nicotine dependence and accelerometer - determined pa behavior ( both light - intensity and moderate - to - vigorous pa ( mvpa ) ) among a national sample of us adult smokers .
we also explored the association between nicotine dependence and accelerometer - determined sedentary behavior given the emerging research demonstrating that sedentary behavior , independent of pa , is associated with worse health outcomes ( e.g. , cardiovascular disease ) .
data for the present study were obtained from the 2003 - 2006 national health and nutrition examination survey ( nhanes ) .
nhanes uses a representative sample of noninstitutionalized us civilians , selected by a complex , multistage probability design .
the survey consists of two primary components , including participants being interviewed in their homes and subsequently examined in mobile examination centers ( mecs ) . with regard to the study variables ,
the study was approved by the national center for health statistics ethics review board , with informed consent obtained from all participants prior to data collection . in the 2003 - 2006 nhanes cycles
1,451 provided data on the covariates ( e.g. , age , gender , race - ethnicity , poverty level , emphysema , bronchitis , hypertension , cotinine , body mass index ( bmi ) ) , not including accelerometer wear time .
lastly , after excluding those with missing or insufficient accelerometry data ( < 4 days of 10 + h / day of monitoring data ) , 851 adult ( 20 - 85 years ) participants remained , with these individuals constituting the analytic sample . when comparing the analytic sample to the 600 participants that were excluded because of missing or insufficient accelerometry data , there were no differences by race - ethnicity ( p = 0.21 ) , bmi ( p = 0.07 ) , cotinine ( p = 0.15 ) , and bronchitis ( p = 0.84 ) ; however , those excluded were more likely to be female ( 47.6 vs 39.1% ; p = 0.001 ) , younger ( 40.4 vs 47.3 years ; p < 0.001 ) , had a lower poverty level score ( 2.0 vs 2.3 ; p < 0.001 ) , and were less likely to have emphysema ( 2.8 vs 4.9% ; p = 0.04 ) or hypertension ( 22.5 vs 30.4% ; p = 0.001 ) . these are unweighted estimates . using the fagerstrom test for nicotine dependence scale ,
two self - reported questions were used to assess nicotine dependence : i )  on average , how many cigarettes do you now smoke per day ?  ( responses of 10 or less , 11 - 20 , 21 - 30 , and 31 + , respectively , were coded as 0 , 1 , 2 , and 3 ) , and ii )  how soon after you wake up do you smoke ? 
( responses : within 5 min , from 6 to 30 min , from more than 30 min to 1 h , and more than 1 h , respectively , were coded as 3 , 2 , 1 , and 0 ) . as a result ,
this nicotine dependence scale ranged from 0 to 6 , with higher scores indicating greater nicotine dependence . at the mec
, participants who were not prevented by impairments of walking or wearing an accelerometer were issued an actigraph 7164 accelerometer .
participants were asked to wear the accelerometer on the right hip for 7 days following their examination .
activity counts between 100 and 2,019 counts per min were used to classify time spent in light - intensity pa ; activity counts between 2,020 and 5,998 counts per min were used to classify time spent at moderate - intensity ; and activity counts at or greater than 5,999 counts per min were used to classify time spent at vigorous - intensity . given that participants spent little time at or above vigorous intensity ( mean = 0.62 min / day , standard error ( se ) = 0.1 ) , moderate and vigorous intensity pa
was combined as an estimate of mvpa . for the analyses described here , and to ensure habitual pa patterns were assessed , only those participants with at least 4 days with 10 or more h / day of monitoring data were included in the analyses .
nonwear of the accelerometer was defined by a period of a minimum of 60 consecutive min of zero activity counts , with the allowance of 1 - 2 min of activity counts between 0 and 100 .
covariates included age ( continuous ) , gender ( male / female ) , race - ethnicity ( mexican american , other hispanic , non - hispanic white ; non - hispanic black , and other race ) , poverty level ( range = 0 - 5 ) , measured hypertension ( 140 mmhg(systolic ) or 90 mmhg ( diastolic ) or if they were taking blood pressure lowering medication ) , physician - diagnosed emphysema , physician - diagnosed bronchitis , measured bmi ( kg / m ) , cotinine ( continuous ; ng / ml ) , and accelerometer wear time ( h / day ) . as a measure of socioeconomic status ,
poverty level was assessed from the poverty - to - income ratio , with a value below 1 considered below the poverty threshold .
the poverty level is calculated by dividing the family income by the poverty guidelines , which is specific to the family size , year assessed , and state of residence .
serum cotinine was measured by an isotope dilution - high performance liquid chromatography / atmospheric pressure chemical ionization tandem mass spectrometry .
statistical analyses ( stata , version 12.0 , college station , tx ) accounted for the complex survey design used in nhanes . to account for oversampling , nonresponse , noncoverage , and to provide nationally representative estimates ,
all analyses included the use of survey sample weights , stratum , and primary sampling units .
multivariable regression analysis was used to examine the association between nicotine dependence ( predictor variable ) and pa / sedentary behavior ; models were computed separately for sedentary behavior , light - intensity pa , and mvpa .
a negative binomial regression analysis was computed for the mvpa model given that mvpa was considerably skewed .
all models were adjusted for age , gender , race - ethnicity , poverty level , hypertension , emphysema , bronchitis , bmi , cotinine , and accelerometer wear time .
interaction analyses were first computed to examine if there was an interaction effect of nicotine dependence and age ; nicotine dependence and gender ; and nicotine dependence and race - ethnicity . to examine a potential interaction effect ,
the cross - product term of nicotine dependence and the demographic variable ( i.e. , age , gender , or race - ethnicity ) was entered into the model , along with the main effect variables and the covariates .
these three interaction models ( with mvpa as the outcome variable ) showed that the interaction variable for nicotine dependence and age was significant (  = 0.07 ; p = 0.02 ) ; however , the models examining an interaction effect for nicotine dependence and gender (  = 0.83 ; p = 0.30 ) and nicotine dependence and race - ethnicity (  = 1.06 ; p = 0.13 ) were not significant . given the nicotine dependence and age interaction effect , the results presented herein are stratified by age group ( 20 - 29 years , n = 126 ; 30 - 49 years , n = 351 ; and 50 + years , n = 374 ) .
more specifically , three multivariable regression analyses were computed that examined the association between nicotine dependence ( predictor variable ) and mvpa : one for 20 - 29-year - olds ; one for 30 - 49-year - olds ; and one for 50 + year olds .
these age groups were chosen based on a visual inspection of a scatter plot ( not shown ) delineating a nonlinear relationship between age and nicotine dependence .
similarly , three separate age - stratified models were computed for light - intensity pa and three separate age - stratified models were computed for sedentary behavior .
data for the present study were obtained from the 2003 - 2006 national health and nutrition examination survey ( nhanes ) .
nhanes uses a representative sample of noninstitutionalized us civilians , selected by a complex , multistage probability design .
the survey consists of two primary components , including participants being interviewed in their homes and subsequently examined in mobile examination centers ( mecs ) . with regard to the study variables ,
the study was approved by the national center for health statistics ethics review board , with informed consent obtained from all participants prior to data collection . in the 2003 - 2006 nhanes cycles
1,451 provided data on the covariates ( e.g. , age , gender , race - ethnicity , poverty level , emphysema , bronchitis , hypertension , cotinine , body mass index ( bmi ) ) , not including accelerometer wear time .
lastly , after excluding those with missing or insufficient accelerometry data ( < 4 days of 10 + h / day of monitoring data ) , 851 adult ( 20 - 85 years ) participants remained , with these individuals constituting the analytic sample . when comparing the analytic sample to the 600 participants that were excluded because of missing or insufficient accelerometry data , there were no differences by race - ethnicity ( p = 0.21 ) , bmi ( p = 0.07 ) , cotinine ( p = 0.15 ) , and bronchitis ( p = 0.84 ) ; however , those excluded were more likely to be female ( 47.6 vs 39.1% ; p = 0.001 ) , younger ( 40.4 vs 47.3 years ; p < 0.001 ) , had a lower poverty level score ( 2.0 vs 2.3 ; p < 0.001 ) , and were less likely to have emphysema ( 2.8 vs 4.9% ; p = 0.04 ) or hypertension ( 22.5 vs 30.4% ; p = 0.001 ) . these are unweighted estimates .
using the fagerstrom test for nicotine dependence scale , two self - reported questions were used to assess nicotine dependence : i )  on average , how many cigarettes do you now smoke per day ?  ( responses of 10 or less , 11 - 20 , 21 - 30 , and 31 + , respectively , were coded as 0 , 1 , 2 , and 3 ) , and ii )  how soon after you wake up do you smoke ? 
( responses : within 5 min , from 6 to 30 min , from more than 30 min to 1 h , and more than 1 h , respectively , were coded as 3 , 2 , 1 , and 0 ) . as a result , this nicotine dependence scale ranged from 0 to 6 , with higher scores indicating greater nicotine dependence .
at the mec , participants who were not prevented by impairments of walking or wearing an accelerometer were issued an actigraph 7164 accelerometer .
participants were asked to wear the accelerometer on the right hip for 7 days following their examination .
detailed information on the actigraph accelerometer can be found elsewhere . for the present study ,
activity counts between 100 and 2,019 counts per min were used to classify time spent in light - intensity pa ; activity counts between 2,020 and 5,998 counts per min were used to classify time spent at moderate - intensity ; and activity counts at or greater than 5,999 counts per min were used to classify time spent at vigorous - intensity . given that participants spent little time at or above vigorous intensity ( mean = 0.62 min / day , standard error ( se ) = 0.1 ) ,
moderate and vigorous intensity pa was combined as an estimate of mvpa . for the analyses described here , and to ensure habitual pa patterns were assessed , only those participants with at least 4 days with 10 or more h / day of monitoring data were included in the analyses .
nonwear of the accelerometer was defined by a period of a minimum of 60 consecutive min of zero activity counts , with the allowance of 1 - 2 min of activity counts between 0 and 100 .
covariates included age ( continuous ) , gender ( male / female ) , race - ethnicity ( mexican american , other hispanic , non - hispanic white ; non - hispanic black , and other race ) , poverty level ( range = 0 - 5 ) , measured hypertension ( 140 mmhg(systolic ) or 90 mmhg ( diastolic ) or if they were taking blood pressure lowering medication ) , physician - diagnosed emphysema , physician - diagnosed bronchitis , measured bmi ( kg / m ) , cotinine ( continuous ; ng / ml ) , and accelerometer wear time ( h / day ) . as a measure of socioeconomic status ,
poverty level was assessed from the poverty - to - income ratio , with a value below 1 considered below the poverty threshold .
the poverty level is calculated by dividing the family income by the poverty guidelines , which is specific to the family size , year assessed , and state of residence .
serum cotinine was measured by an isotope dilution - high performance liquid chromatography / atmospheric pressure chemical ionization tandem mass spectrometry .
statistical analyses ( stata , version 12.0 , college station , tx ) accounted for the complex survey design used in nhanes . to account for oversampling , nonresponse , noncoverage , and to provide nationally representative estimates ,
all analyses included the use of survey sample weights , stratum , and primary sampling units .
multivariable regression analysis was used to examine the association between nicotine dependence ( predictor variable ) and pa / sedentary behavior ; models were computed separately for sedentary behavior , light - intensity pa , and mvpa .
a negative binomial regression analysis was computed for the mvpa model given that mvpa was considerably skewed .
all models were adjusted for age , gender , race - ethnicity , poverty level , hypertension , emphysema , bronchitis , bmi , cotinine , and accelerometer wear time .
interaction analyses were first computed to examine if there was an interaction effect of nicotine dependence and age ; nicotine dependence and gender ; and nicotine dependence and race - ethnicity . to examine a potential interaction effect ,
the cross - product term of nicotine dependence and the demographic variable ( i.e. , age , gender , or race - ethnicity ) was entered into the model , along with the main effect variables and the covariates .
these three interaction models ( with mvpa as the outcome variable ) showed that the interaction variable for nicotine dependence and age was significant (  = 0.07 ; p = 0.02 ) ; however , the models examining an interaction effect for nicotine dependence and gender (  = 0.83 ; p = 0.30 ) and nicotine dependence and race - ethnicity (  = 1.06 ; p = 0.13 ) were not significant . given the nicotine dependence and age interaction effect , the results presented herein are stratified by age group ( 20 - 29 years , n = 126 ; 30 - 49 years , n = 351 ; and 50 + years , n = 374 ) .
more specifically , three multivariable regression analyses were computed that examined the association between nicotine dependence ( predictor variable ) and mvpa : one for 20 - 29-year - olds ; one for 30 - 49-year - olds ; and one for 50 + year olds .
these age groups were chosen based on a visual inspection of a scatter plot ( not shown ) delineating a nonlinear relationship between age and nicotine dependence .
similarly , three separate age - stratified models were computed for light - intensity pa and three separate age - stratified models were computed for sedentary behavior .
older smokers , compared to younger smokers , had a higher poverty - to - income ratio , higher cotinine value , were more likely to be hypertensive , have emphysema , chronic bronchitis , engaged in more sedentary behavior , and less light - intensity pa and mvpa [ table 1 ] . also , older smokers had greater nicotine dependence .
weighted characteristics of us smokers across age groups , 2003 - 2006 nhanes ( n = 851 ) multivariable regression analyses showed that there was no association between nicotine dependence and pa / sedentary behavior for the two younger age groups [ table 2 ] .
however , among smokers 50 + years , those with greater nicotine dependence engaged in more sedentary behavior (  = 11.4 , p = 0.02 ) and less light - intensity pa (  = 9.6 , p = 0.03 ) and mvpa (  = 0.14 , p = 0.003 ) .
notably , after applying a bonferroni - corrected p - value ( i.e. , p < 0.005 ) , nicotine dependence was only associated with mvpa .
these regression analyses were adjusted for age , gender , race - ethnicity , poverty level , hypertension , emphysema , bronchitis , accelerometer wear time , cotinine , and bmi . when additional covariates ( e.g. , pack years ) were entered in the model , the results were unchanged ( data not shown ) .
multivariable regression analysis examining the association between nicotine dependence ( independent variable ) and physical activity / sedentary behavior , 2003 - 2006 nhanes ( n = 851 ) these findings suggest that nicotine dependence is only associated with pa among older individuals , with older individuals generally having greater nicotine dependence ; nicotine dependence values across the three age groups , respectively , was 2.0 , 2.5 , and 3.0 .
further analyses were computed to examine if a particular nicotine dependence threshold influenced the nicotine dependence - pa relationship . when nicotine dependence was divided into tertiles ( 1.06 ; tertile 1 , 3.0 , tertile 2 ; and 4.6 , tertile 3 ( values are means ) ) , there was no association between these nicotine dependence categories and pa .
for example , in a multivariable regression model among the entire sample , middle tertile ( vs bottom tertile ) of nicotine dependence (  = 0.03 , p = 0.75 ) was not associated with mvpa nor was the top tertile ( vs bottom tertile ) (  = 0.07 , p = 0.47 ) .
although a considerable amount of research has demonstrated an inverse association between smoking status and pa , to our knowledge , few studies have examined the association between nicotine dependence and pa .
these studies showed that nicotine dependence was inversely associated with self - reported leisure - time pa .
the present study adds to the literature by examining this understudied topic , stratifying analyses by age , employing a national sample of us adult smokers , employing an objective measure of pa , and also considering the influence that nicotine dependence may have on sedentary behavior and light - intensity pa .
overall , our findings demonstrate an inverse association between nicotine dependence and mvpa , with some evidence of an association between nicotine dependence and light - intensity pa and sedentary behavior .
notably , these associations were only observed for adults 50 years and older . a possible explanation for the null findings for the younger age groups may be because of their lower degree of nicotine dependence .
nicotine dependence may displace the amount of time to engage in pa and is also associated with other outcomes ( e.g. , depression ) that are associated with physical inactivity .
our findings further demonstrate that older adults who are more nicotine dependent engage in less pa ( both mvpa and light - intensity ) and more sedentary behavior than their less nicotine - dependent counterparts . as a result , older adults with greater nicotine dependence , in particular , are in need of pa promotion .
pa promotion may be particularly difficult among this population given the established age- and smoking - induced effects , such as reduced mobility and diminished lung capacity , which may increase exercise intolerance .
given the emerging research showing that sedentary behavior and light - intensity pa are independent predictors of health among older adults ; promoting light - intensity pa , at least initially , may be a sensible strategy to increase long - term pa engagement among nicotine dependent smokers . in turn , this may help prevent the development of numerous comorbidities associated with physical inactivity .
further , and although speculative , such pa promotion may help to facilitate the cessation of smoking as regular pa engagement has been shown to reduce nicotine dependence through reduced nicotine cravings , more quit attempts , and success in stopping smoking .
in conclusion , our findings demonstrate that , among us adults 50 + years of age , nicotine dependence is inversely associated with mvpa and light - intensity pa and positively associated with sedentary behavior .
a limitation of this study includes the cross - sectional design , which precludes the ability to render causation . as a result , future research employing an objective measure of pa and utilizing a prospective or experimental study design is warranted .
further , the included sample differed from the excluded sample on several parameters , including gender , age , poverty level , and health status .
lastly , depression data was not available in both of the evaluated nhanes cycles ; therefore , future research should consider the effects of depression when examining the relationship between nicotine dependence and objectively - measured pa .
 background : research has previously demonstrated an inverse association between smoking status and physical activity ; however , few studies have examined the association between nicotine dependence and physical activity or sedentary behavior.aim:this study examined the association between nicotine dependence and accelerometer - determined physical activity and sedentary behavior.materials and methods : data from the 2003 - 2006 national health and nutrition examination survey ( nhanes ) were used . 
 a total of 851 adult ( 20 years ) smokers wore an accelerometer for 4 days and completed the fagerstrom test for nicotine dependence scale . 
 regression models were used to examine the association between nicotine dependence and physical activity / sedentary behavior.results:after adjusting for age , gender , race - ethnicity , poverty level , hypertension , emphysema , bronchitis , body mass index ( bmi ) , cotinine , and accelerometer wear time , smokers 50 + years of age with greater nicotine dependence engaged in more sedentary behavior (  = 11.4 , p = 0.02 ) and less light - intensity physical activity (  = 9.6 , p = 0.03 ) and moderate - to - vigorous physical activity ( mvpa ;  = 0.14 , p = 0.003 ) than their less nicotine dependent counterparts.conclusion:older adults who are more nicotine dependent engage in less physical activity ( both mvpa and light - intensity ) and more sedentary behavior than their less nicotine dependent counterparts . 
Introduction
Materials and Methods
Design and participants
Measurement of nicotine dependence
Measurement of PA
Measurement of covariates
Data analysis
Results
Discussion
Conclusion