Abstracts

INTRODUCTION

Smoking is a major public health problem worldwide. In the 20th century, tobacco use killed 100 million people worldwide. Smoking accounts for 5.4 million deaths per year worldwide, and it is estimated that it will account for more than 8.0 million deaths per year in 2030. Approximately 80% of these deaths will occur in developing countries, and smoking is currently the leading cause of preventable death worldwide.⁽¹1. World Health Organization. WHO Report on the Global Tobacco Epidemic 2008: The Mpower Package. Geneva: World Health Organization; 2008.⁾

The impact of tobacco use on health is well known, tobacco use accounting for 90% of all cases of lung cancer, 75% of all cases of chronic bronchitis, and 25% of all cases of ischemic heart disease.⁽²2. Wünsch Filho V, Mirra AP, López RV, Antunes LF. Tobacco smoking and cancer in Brazil: evidence and prospects [Article in Portuguese]. Rev Bras Epidemiol. 2010;13(2):175-87. http://dx.doi.org/10.1590/S1415-790X2010000200001
https://doi.org/10.1590/S1415-790X201000... ⁾ Individuals who smoke more than 20 cigarettes per day are significantly different from nonsmokers in terms of their FEV₁.⁽³3. Urrutia I, Capelastegui A, Quintana JM, Mu-iozguren N, Basagana X, Sunyer J, et al. Smoking habit, respiratory symptoms and lung function in young adults. Eur J Public Health. 2005;15(2):160-5. http://dx.doi.org/10.1093/eurpub/cki113
https://doi.org/10.1093/eurpub/cki113... ⁾ This is due to the fact that smoking causes acute lung changes, including changes in airflow resistance, cough, and airway irritation.⁽⁴4. Tantisuwat A, Thaveeratitham P. Effects of smoking on chest expansion, lung function, and respiratory muscle strength of youths. J Phys Ther Sci. 2014;26(2):167-70. http://dx.doi.org/10.1589/jpts.26.167
https://doi.org/10.1589/jpts.26.167... ⁾

Lung function decline is less pronounced in smokers who engage in moderate- to high-intensity physical activity. ⁽⁵5. Garcia-Aymerich J, Lange P, Benet M, Schnohr P, Antó JM. Regular physical activity modifies smoking-related lung function decline and reduces risk of chronic obstructive pulmonary disease: a population-based cohort study. Am J Respir Crit Care Med. 2007;175(5):458-63. http://dx.doi.org/10.1164/rccm.200607-896OC
https://doi.org/10.1164/rccm.200607-896O... ⁾ Studies have shown that regular physical activity is effective in preventing chronic diseases such as cardiovascular disease, diabetes, cancer, hypertension, obesity, depression, and osteoporosis. It has been suggested that there is a significant association between physical activity and health status, increased physical fitness resulting in additional health benefits. ⁽⁶6. Warburton DE, Nicol CW, Bredin SS. Health benefits of physical activity: the evidence. CMAJ. 2006;174(6):801-9. http://dx.doi.org/10.1503/cmaj.051351
https://doi.org/10.1503/cmaj.051351... ⁾ Other studies have shown that endurance training in nonsmokers results in adaptations of the cardiorespiratory and neuromuscular systems that increase the supply of oxygen to the mitochondria, thus contributing to maintaining physical fitness.⁽⁷7. Cheng YJ, Macera CA, Addy CL, Sy FS, Wieland D, Blair SN. Effects of physical activity on exercise tests and respiratory function. Br J Sports Med. 2003;37(6):521-8. http://dx.doi.org/10.1136/bjsm.37.6.521
https://doi.org/10.1136/bjsm.37.6.521... ^,88. Jones AM, Carter H. The effect of endurance training on parameters of aerobic fitness. Sports Med. 2000;29(6):373-86. http://dx.doi.org/10.2165/00007256-200029060-00001
https://doi.org/10.2165/00007256-2000290... ⁾ It has been suggested that smoking reduces cardiorespiratory fitness and lung function.⁽⁹9. Hashizume K, Kusaka Y, Kawahara K. Effects of cigarette smoking on endurance performance levels of 16- to 19-year-old males. Environ Health Prev Med. 1999;4(2):75-80. http://dx.doi.org/10.1007/BF02931998
https://doi.org/10.1007/BF02931998... ^,1010. Lee CL, Chang WD. The effects of cigarette smoking on aerobic and anaerobic capacity and heart rate variability among female university students. Int J Womens Health. 2013;5:667-79. http://dx.doi.org/10.2147/IJWH.S49220
https://doi.org/10.2147/IJWH.S49220... ⁾ In addition, significant differences have been found between physically active and physically inactive smokers regarding fatigue immediately after the six-minute walk test and during the recovery period, at two minutes after the test.⁽¹¹11. Furlanetto KC, Mantoani LC, Bisca G, Morita AA, Zabatiero J, Proença M, et al. Reduction of physical activity in daily life and its determinants in smokers without airflow obstruction. Respirology. 2014;19(3):369-75. http://dx.doi.org/10.1111/resp.12236
https://doi.org/10.1111/resp.12236... ⁾

Regular physical exercise can counter the negative effects of smoking through an anti-inflammatory and antioxidant mechanism. Physical activity and smoking interact antagonistically: inflammatory markers that are produced in the lung and are related to a decline in cardiorespiratory fitness are suppressed by physical exercise.⁽⁵5. Garcia-Aymerich J, Lange P, Benet M, Schnohr P, Antó JM. Regular physical activity modifies smoking-related lung function decline and reduces risk of chronic obstructive pulmonary disease: a population-based cohort study. Am J Respir Crit Care Med. 2007;175(5):458-63. http://dx.doi.org/10.1164/rccm.200607-896OC
https://doi.org/10.1164/rccm.200607-896O... ⁾

Physical activity can be assessed by a variety of methods, including direct observation, questionnaires, self-report diaries, and motion sensors, such as pedometers and accelerometers.⁽¹²12. Atkin AJ, Gorely T, Clemes SA, Yates T, Edwardson C, Brage S, et al. Methods of measurement in epidemiology: sedentary behaviour. Int J Epidemiol. 2012;41(5):1460-71. http://dx.doi.org/10.1093/ije/dys118
https://doi.org/10.1093/ije/dys118... ⁾ Objective assessment is performed by motion sensors, which are instruments that are used in order to detect body motion and determine the level of physical activity in daily life (PADL) over a period of time. Accelerometers are real-time motion capture sensors that are sensitive to acceleration.⁽¹³13. Pitta F, Troosters T, Probst VS, Spruit MA, Decramer M, Gosselink R. Quantifying physical activity in daily life with questionnaires and motion sensors in COPD. Eur Respir J. 2006;27(5):1040-55. http://dx.doi.org/10.1183/09031936.06.00064105
https://doi.org/10.1183/09031936.06.0006... ⁾

Few studies have examined the preventive effect of physical activity on the lung function of smokers, the level of PADL having been determined on the basis of self-reports, face-to-face interviews, or physical activity questionnaires. Using pedometers, Furlanetto et al.⁽¹¹11. Furlanetto KC, Mantoani LC, Bisca G, Morita AA, Zabatiero J, Proença M, et al. Reduction of physical activity in daily life and its determinants in smokers without airflow obstruction. Respirology. 2014;19(3):369-75. http://dx.doi.org/10.1111/resp.12236
https://doi.org/10.1111/resp.12236... ⁾ found that the mean number of daily steps was significantly lower in adult smokers than in adult controls, the former also having lower physical capacity, worse lung function, and greater sensation of fatigue. However, there is a lack of studies in which the level of PADL in smokers is more accurately determined with the use of triaxial accelerometers.

There is evidence that a higher level of PADL reduces smoking-related complications. However, there is a need for further clarification of the association between the level of PADL and lung function in smokers. If this association is found to be consistent, preventive strategies can be devised. Longitudinal studies of the role that a higher level of objectively measured PADL has in preventing lung function decline in smokers could contribute to preventing smoking-related complications, which consume a significant proportion of health care resources in Brazil and the world.⁽¹⁴14. Pinto M, Ugá MA. Os custos de doenças tabaco-relacionadas para o Sistema Único de Saúde. Cad Saude Publica. 2010;26(6):1234-45. http://dx.doi.org/10.1590/S0102-311X2010000600016
https://doi.org/10.1590/S0102-311X201000... ⁾

We hypothesized that smokers who have a higher level of PADL (more accurately determined by triaxial accelerometry) have relatively preserved lung function, regardless of their smoking history. Confirmation of our hypothesis would support the need for strategies to increase the level of PADL in smokers in order to reduce the damage caused by smoking. Therefore, we sought to determine whether the level of PADL, as determined by triaxial accelerometry, was associated with lung function in adult smokers.

METHODS

This was a cross-sectional study involving a convenience sample of adult smokers selected from among the participants of a study conducted in the Federal University of São Paulo Laboratory of Epidemiology and Human Movement, located in the city of Santos, Brazil. The study included 62 adult smokers who were 20 years of age or older and had no cardiac, respiratory, or metabolic diseases limiting their exercise capacity. In brief, this was a population-based epidemiological study whose primary objective was to determine the association of sedentary behavior and physical inactivity with the development of chronic diseases. The exclusion criteria were as follows: a spirometric diagnosis of COPD; problems indicating inability to perform PADL adequately; being a smoker with a smoking history of fewer than 1.5 pack-years or more than 50 pack-years; and being a former smoker.⁽¹⁵15. Santos JD, Silveira DV, Oliveira DF, Caiaffa WT. Instruments used to evaluate smoking habits: a systematic review [Article in Portuguese]. Cien Saude Colet. 2011;16(12):4707-20. http://dx.doi.org/10.1590/S1413-81232011001300020
https://doi.org/10.1590/S1413-8123201100... ⁾

The following demographic variables were analyzed: age; gender; race; place of birth; level of education; and socioeconomic status. After being selected for inclusion, all participants were informed of the procedures, discomfort, and risks associated with the present study and gave written informed consent. The study project was approved by the Federal University of São Paulo Human Research Ethics Committee (Protocol no. 186.796).

Initial clinical evaluation included history taking for previous health problems and use of medications. The risk of cardiovascular events was determined on the basis of the following risk factors: age; family history; smoking history; hypertension; dyslipidemia or hypercholesterolemia; diabetes or hyperglycemia; obesity; and sedentary lifestyle.

Smoking status was determined by self-report, and smoking history was calculated by multiplying the duration of smoking in years by the number of cigarettes smoked per day and dividing the result by 20 (the number of cigarettes in one pack). Individuals who reported current smoking and having smoked 100 or more cigarettes in their lifetime at the time of the study were defined as smokers.⁽¹⁵15. Santos JD, Silveira DV, Oliveira DF, Caiaffa WT. Instruments used to evaluate smoking habits: a systematic review [Article in Portuguese]. Cien Saude Colet. 2011;16(12):4707-20. http://dx.doi.org/10.1590/S1413-81232011001300020
https://doi.org/10.1590/S1413-8123201100... ⁾

After anthropometric measurements, including weight, height, and BMI calculation, all participants were evaluated as described below.

Lung function was assessed by forced spirometry (Quark PFT; Cosmed, Rome, Italy). FEV₁, FVC, FEV₁/FVC, and PEF were determined in accordance with the American Thoracic Society criteria.⁽¹⁶16. Miller MR, Hankinson J, Brusasco V, Burgos F, Casaburi R, Coates A, et al. Standardisation of spirometry. Eur Respir J. 2005;26(2):319-38. http://dx.doi.org/10.1183/09031936.05.00034805
https://doi.org/10.1183/09031936.05.0003... ⁾ Spirometric indices were expressed as absolute values and as a percentage of reference values.⁽¹⁷17. Pereira CA, Sato T, Rodrigues SC. New reference values for forced spirometry in white adults in Brazil. J Bras Pneumol. 2007;33(4):397-406. http://dx.doi.org/10.1590/S1806-37132007000400008
https://doi.org/10.1590/S1806-3713200700... ⁾

The level of PADL was determined by the International Physical Activity Questionnaire (IPAQ), which assesses total energy expenditure in metabolic equivalent task-minutes per week (MET-min/wk) and time spent in daily physical activity. PADL was classified as vigorous, moderate, or light, measured in MET-min/wk, and divided into four domains: work; transport; household chores; and recreation and leisure. The total IPAQ score is calculated by summing the individual domain scores. The IPAQ-long form was used, consisting of 27 questions regarding physical activity. The participants were instructed to answer the questions on the basis of the week prior to the administration of the IPAQ. ⁽¹⁸18. Hallal PC, Gomez LF, Parra DC, Lobelo F, Mosquera J, Florindo AA, et al. Lessons learned after 10 years of IPAQ use in Brazil and Colombia. J Phys Act Health. 2010;7 Suppl 2:S259-64.⁾ The level of PADL was also assessed with a widely used triaxial accelerometer (GT3X ActiGraph; MTI, Pensacola, FL, USA).⁽¹⁹19. Troiano RP, Berrigan D, Dodd KW, Mâsse LC, Tilert T, McDowell M. Physical activity in the United States measured by accelerometer. Med Sci Sports Exerc. 2008;40(1):181-8. http://dx.doi.org/10.1249/mss.0b013e31815a51b3
https://doi.org/10.1249/mss.0b013e31815a...

20. Trost SG, Way R, Okely AD. Predictive validity of three ActiGraph energy expenditure equations for children. Med Sci Sports Exerc. 2006;38(2):380-7. http://dx.doi.org/10.1249/01.mss.0000183848.25845.e0
https://doi.org/10.1249/01.mss.000018384...

21. Evenson KR, Wen F, Metzger JS, Herring AH. Physical activity and sedentary behavior patterns using accelerometry from a national sample of United States adults. Int J Behav Nutr Phys Act. 2015;12:20. http://dx.doi.org/10.1186/s12966-015-0183-7
https://doi.org/10.1186/s12966-015-0183-... ^-2222. Loprinzi PD, Walker JF. Nicotine Dependence, Physical Activity, and Sedentary Behavior among Adult Smokers. N Am J Med Sci. 2015;7(3):94-9. http://dx.doi.org/10.4103/1947-2714.153920
https://doi.org/10.4103/1947-2714.153920... ⁾ A triaxial accelerometer measures the duration and intensity of physical activity. The participants were instructed to wear the device on an elastic belt placed on their dominant hip and left in place for seven days. A valid day was defined as at least 12 h of accelerometer use. All participants were instructed to remove the device before engaging in water-based activities, such as bathing and swimming, and at bedtime. Only the data from the participants who used the accelerometer for at least four valid days were analyzed.⁽¹⁹19. Troiano RP, Berrigan D, Dodd KW, Mâsse LC, Tilert T, McDowell M. Physical activity in the United States measured by accelerometer. Med Sci Sports Exerc. 2008;40(1):181-8. http://dx.doi.org/10.1249/mss.0b013e31815a51b3
https://doi.org/10.1249/mss.0b013e31815a... ⁾ On the basis of its intensity, physical activity was classified as follows: physical inactivity or light physical activity, fewer than 3.00 MET-min/wk; moderate physical activity, 3.00-5.99 MET-min/wk; hard physical activity, 6.00-8.99 MET-min/wk; and very hard physical activity, ≥ 9.00 MET-min/wk.⁽²³23. Freedson PS, Melanson E, Sirard J. Calibration of the Computer Science and Applications, Inc. accelerometer. Med Sci Sports Exerc. 1998;30(5):777-81. http://dx.doi.org/10.1097/00005768-199805000-00021
https://doi.org/10.1097/00005768-1998050... ⁾ The minimum level of PADL, in terms of quantity and intensity, was defined as 150 min/week of moderate to vigorous physical activity.⁽²⁴24. American College of Sports Medicine. ACSM's guidelines for exercise testing and prescription. 8th ed. Philadelphia: Lippincott Williams & Wilkins; 2009.⁾ The participants who were unable to achieve that level of PADL were considered to be physically inactive.

In the present study, statistical analysis was performed with the IBM SPSS Statistics software package, version 23 (IBM Corporation, Armonk, NY, USA). The Kolmogorov-Smirnov test was used in order to determine the normality of continuous variables. Data are presented as mean ± standard deviation or as median (interquartile range).

The study sample size was calculated on the basis of the number of independent variables of interest for inclusion in the multiple regression model. Outcome variables in the regression models included percent predicted FEV₁ and FVC. The models were adjusted for age, gender, weight, height, and six other variables. Smoking history was considered to be the main predictor. Possible predictors were initially evaluated in categories. Demographic and anthropometric characteristics were taken into consideration, as were cardiovascular risk factors. After the bivariate analysis, the variables that were found to be significantly associated with the spirometric indices were included in the multiple regression model, as follows: age; gender; presence of hypertension; presence of diabetes mellitus; IPAQ household chores domain score; daily energy expenditure in kcal; and physical inactivity.

The Student's t-test or the Mann-Whitney test was used in order to compare the spirometric indices between males and females according to the presence of comorbidities, such as hypertension, diabetes mellitus, dyslipidemia, obesity, and physical inactivity.

Correlations between the studied variables were tested with Pearson's or Spearman's correlation coefficient, depending on the distribution of the variables. The level of significance was set at 5%.

RESULTS

Among the 62 volunteers in the study sample, obese individuals and females predominated (Table 1). There were significant differences between males and females regarding smoking history, weight, and BMI.

Table 2 shows the correlations between PADL and lung function, FVC having been found to correlate significantly with the IPAQ household chores domain score, energy expenditure in kcal/day, and hard physical activity in h (p < 0.05 for all). The aforementioned variables were also found to correlate significantly with FEV₁. The household chores domain scores were the only IPAQ domain scores that correlated significantly with lung function. PEF was found to correlate significantly with the IPAQ household chores domain score, light physical activity, and hard physical activity. Table 3 shows the bivariate association between lung function data and cardiovascular risk factors. FVC was found to be reduced in the participants with arterial hypertension, and the FEV₁/FVC ratio was found to be reduced in those with diabetes mellitus. Obese participants and those with dyslipidemia were found to have reduced FVC and FEV₁. No significant associations were found between physical inactivity, as determined by accelerometry, and spirometric indices.

Evaluating all predictors, corrected for confounding factors, and using lung function data (FVC and FEV₁, both in % of predicted) as outcome variables, we found that the variables that remained in the model as predictors of lung function were smoking history and the presence of diabetes, as predictors of FVC, and smoking history and the presence of arterial hypertension, as predictors of FEV₁ (Table 4).

DISCUSSION

The present study investigated the association between the level of PADL and lung function in adult smokers without respiratory disease. The level of PADL was directly assessed by triaxial accelerometry over the course of seven days. To our knowledge, there is little information regarding the use of triaxial accelerometry for determining the level of PADL. After adjustment for the main confounding factors, no association was found between an adequate level of PADL and better lung function.

As expected, smoking history was a predictor of worse FVC and FEV₁, even after having been adjusted for confounding factors. Studies have shown that smoking history is the main predictor of reduced FEV₁ in smokers with a normal FEV₁/FVC ratio.⁽²⁵25. Masuko H, Sakamoto T, Kaneko Y, Iijima H, Naito T, Noguchi E, et al. Lower FEV1 in non-COPD, nonasthmatic subjects: association with smoking, annual decline in FEV1, total IgE levels, and TSLP genotypes. Int J Chron Obstruct Pulmon Dis. 2011;6:181-9.⁾ Smoking is also associated with dysregulation of gene expression in the small airway epithelium and accelerates the aging of the airways, as well as being the principal factor responsible for progressive lung function decline.⁽²⁶26. Walters MS, De BP, Salit J, Buro-Auriemma LJ, Wilson T, Rogalski AM, et al. Smoking accelerates aging of the small airway epithelium. Respir Res. 2014;15:94. http://dx.doi.org/10.1186/s12931-014-0094-1
https://doi.org/10.1186/s12931-014-0094-... ⁾

Lallukka et al.⁽²⁷27. Lallukka T, Rahkonen O, Lahelma E, Lahti J. Joint associations of smoking and physical activity with disability retirement: a register-linked cohort study. BMJ Open. 2015;5(7):e006988. http://dx.doi.org/10.1136/bmjopen-2014-006988
https://doi.org/10.1136/bmjopen-2014-006... ⁾ conducted a cohort study and concluded that smoking and physical inactivity are associated with disability retirement and that even hard physical activity is not sufficient to eliminate the adverse effects that smoking has on health. Elderly smokers have reduced exercise capacity when compared with elderly never-smokers, and tobacco exposure is associated with reduced quality of life regardless of the level of physical activity.⁽²⁸28. Mesquita R, Gonçalves CG, Hayashi D, Costa Vde S, Teixeira Dde C, de Freitas ER, et al. Smoking status and its relationship with exercise capacity, physical activity in daily life and quality of life in physically independent, elderly individuals. Physiotherapy. 2015;101(1):55-61. http://dx.doi.org/10.1016/j.physio.2014.04.008
https://doi.org/10.1016/j.physio.2014.04... ⁾ Smoking is associated with evidence of mild obstruction and accelerates lung function decline in adolescents. Female adolescents are possibly more vulnerable to the effects of smoking on lung function than are male adolescents.⁽²⁹29. Gold DR, Wang X, Wypij D, Speizer FE, Ware JH, Dockery DW. Effects of cigarette smoking on lung function in adolescent boys and girls. N Engl J Med. 1996;335(13):931-7. http://dx.doi.org/10.1056/NEJM199609263351304
https://doi.org/10.1056/NEJM199609263351... ⁾ We believe that the benefits of PADL were not enough to make up for the damage caused by smoking.

We observed a crucial association between the presence of diabetes mellitus and lung function in our participants. Our results are in agreement with those of previous studies.⁽³⁰30. Cazzola M, Calzetta L, Rogliani P, Lauro D, Novelli L, Page CP, et al. High glucose enhances responsiveness of human airways smooth muscle via the Rho/ROCK pathway. Am J Respir Cell Mol Biol. 2012;47(4):509-16. http://dx.doi.org/10.1165/rcmb.2011-0449OC
https://doi.org/10.1165/rcmb.2011-0449OC... ^,3131. Shah SH, Sonawane P, Nahar P, Vaidya S, Salvi S. Pulmonary function tests in type 2 diabetes mellitus and their association with glycemic control and duration of the disease. Lung India. 2013;30(2):108-12. http://dx.doi.org/10.4103/0970-2113.110417
https://doi.org/10.4103/0970-2113.110417... ⁾ Lung volume changes reducing lung compliance and DLCO have been described in patients with diabetes. This is probably due to a reduction in pulmonary capillary blood volume as a result of diabetes mellitus. Impaired lung function in individuals with diabetes suggests that the lung is a "target organ" in diabetes mellitus. ⁽³²32. Sandler M. Is the lung a 'target organ' in diabetes mellitus? Arch Intern Med. 1990;150(7):1385-8. http://dx.doi.org/10.1001/archinte.1990.00390190051006
https://doi.org/10.1001/archinte.1990.00... ⁾ Systematic reviews have examined lung function in patients with diabetes mellitus. Reduced FEV₁ and FVC have been found to be associated with type 1 diabetes and type 2 diabetes.⁽³³33. Kinney GL, Black-Shinn JL, Wan ES, Make B, Regan E, Lutz S, et al. Pulmonary function reduction in diabetes with and without chronic obstructive pulmonary disease. Diabetes Care. 2014;37(2):389-95. http://dx.doi.org/10.2337/dc13-1435
https://doi.org/10.2337/dc13-1435... ⁾ Our results suggest that this association remains significant even in smokers with varying history of smoking. Therefore, diabetes mellitus should be considered a major risk factor for lung function decline and, eventually, COPD. According to the aforementioned studies, moderate to high levels of regular physical activity are associated with reduced lung function decline and reduced risk of COPD in smokers.⁽⁵5. Garcia-Aymerich J, Lange P, Benet M, Schnohr P, Antó JM. Regular physical activity modifies smoking-related lung function decline and reduces risk of chronic obstructive pulmonary disease: a population-based cohort study. Am J Respir Crit Care Med. 2007;175(5):458-63. http://dx.doi.org/10.1164/rccm.200607-896OC
https://doi.org/10.1164/rccm.200607-896O... ^,3434. Pelkonen M, Notkola IL, Lakka T, Tukiainen HO, Kivinen P, Nissinen A. Delaying decline in pulmonary function with physical activity: a 25-year follow-up. Am J Respir Crit Care Med. 2003;168(4):494-9. http://dx.doi.org/10.1164/rccm.200208-954OC
https://doi.org/10.1164/rccm.200208-954O... ⁾ This difference can be attributed to the methods used in order to determine the level of PADL. In the present study, we used triaxial accelerometry, which precisely measures the amount and intensity of PADL. The aforementioned studies involved the use of questionnaires. Despite the size of those studies, the major limitation of questionnaires is that they overestimate the level of PADL. Triaxial motion sensors can overcome some of the limitations of self-report instruments, are not affected by random and systematic errors introduced by interviewees and interviewers, and provide valid and reliable estimates of basic features such as the frequency, duration, and intensity of physical activity, as well as the pattern of physical activity.⁽³⁵35. Ortlieb S, Gorzelniak L, Nowak D, Strobl R, Grill E, Thorand B, et al. Associations between multiple accelerometry-assessed physical activity parameters and selected health outcomes in elderly people--results from the KORA-age study. PLoS One. 2014;9(11):e111206. http://dx.doi.org/10.1371/journal.pone.0111206
https://doi.org/10.1371/journal.pone.011... ⁾ An accurate assessment of physical activity is extremely important when the relationship between exposure to physical activity and a range of health outcomes (e.g., cardiovascular disease, hypertension, and obesity) is examined.⁽³⁶36. Caspersen CJ. Physical activity epidemiology: concepts, methods, and applications to exercise science. Exerc Sport Sci Rev. 1989;17:423-73. http://dx.doi.org/10.1249/00003677-198900170-00015
https://doi.org/10.1249/00003677-1989001... ⁾ In addition, self-reported physical activity is highly susceptible to inaccuracy because self-report instruments depend on the ability of individuals to recall and report their physical activity.⁽²³23. Freedson PS, Melanson E, Sirard J. Calibration of the Computer Science and Applications, Inc. accelerometer. Med Sci Sports Exerc. 1998;30(5):777-81. http://dx.doi.org/10.1097/00005768-199805000-00021
https://doi.org/10.1097/00005768-1998050... ⁾ Our results suggest the need for longitudinal epidemiological studies to investigate the association between lung function and PADL, the latter being more accurately assessed by motion sensors.

The major limitation of the present study is its convenience sample, which can explain the predominance of females and the difference in smoking history between males and females. However, the sample size was sufficient to adjust the regression models to the main confounders of clinical interest.

Our results suggest that there is no association between physical inactivity and lung function in adult smokers, as well as reinforcing the importance of smoking cessation and preventing comorbidities such as diabetes mellitus and arterial hypertension in order to prevent lung function decline and COPD. Therefore, health professionals should focus on health promotion instructions and strategies, as well as on preventing comorbidities in smokers and the general population.

Acknowledgments

The authors would like to thank the Angiocorpore Institute of Cardiovascular Medicine for their support.

References

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