Journal of Childhood Obesity Open Access

Obesity-Related Factors that Affect 6-Minute Walk Test Performance in Thai Obese Children

Jitti Hirunpoom¹, Darunwan Nimpun² and Worawan Jittham^{1* 1}Department Pediatric, Naresuan University, Thailand
²Department Pediatric, Naresuan University, Thailand
^*Correspondence: Worawan Jittham, Department Pediatric, Naresuan University, Thailand, Tel: 66866747200, Email:

Received: 30-Nov-2022, Manuscript No. IPJCO-22-15227; Editor assigned: 02-Dec-2022, Pre QC No. IPJCO-22-15227 (PQ); Reviewed: 16-Dec-2022, QC No. IPJCO-22-15227; Revised: 21-Dec-2022, Manuscript No. IPJCO-22-15227 (R); Published: 28-Dec-2022, DOI: 10.36648/2572-5394.22.7.124

INTRODUCTION

Obesity is a leading risk factor for many chronic non-communicable diseases in both children and adults, which has become a global health concern. From a report by the World Health Organization (WHO) in 2016, the prevalence among children and adolescents aged 5 to 19 increased dramatically from 4% in 1975 to 18% in 2016 [1]. In Thailand, the prevalence of obesity among children aged 6 to 14 years has increased to 13.9% over the past five years [2].

Obesity has detrimental impacts on numerous physiological systems, most notably the cardiovascular system, which includes hypertension (HT), heart failure, atherosclerosis, coronary artery disease, and arrhythmia. Obesity is also associated with obstructive sleep apnea, obesity hypoventilation syndrome, asthma, non-alcoholic fatty liver disease, insulin resistance, type 2 diabetes (DM), among others [3,4].

Adult research on the cardiovascular effects of obesity indicated that weight gain may increase intravascular volume, ventricular hypertrophy, and hypertension. This ultimately induces systolic and diastolic ventricular dysfunction because of the increased ventricular afterload. All these effects would impair cardiac function [3,4]. Moreover, a recent study concluded that obesity increases the incidence of arrhythmias and sudden cardiac arrest [5,6].

A study on heart function in children revealed enlarge cardiac chambers and mass. There was a trend of decreased systolic and diastolic performance, but there was no clinically significant reduction in myocardial function or cardiac capacity [7].

Physical fitness one of the determinants of a healthy lifestyle. The 6-Minute Walk Test (6MWT) is an easily accessible test used to gauge a person’s physical fitness and ability to complete daily tasks [8]. This test consists of a six-minute brisk walk during which the distance is recorded [9]. This method reflects function of numerous systems, including the circulatory, respiratory, and musculoskeletal systems [10].

Numerous studies in the past have used the 6MWT to evaluate risk factors of physical fitness in obesity. Overweight and obese children walked significantly shorter distances than normal-weight children, according to two studies [11,12]. The body mass index (BMI) was the most relevant factor affecting 6MWD. In a 3-month weight loss program for children with obesity, 6MWD increased considerably when BMI decreased [11,13,14].

Cardiovascular and metabolic risk factors are associated with a significantly shorter 6MWD in obese children. The clustering of cardiometabolic risk factors more than 2 factors, including fasting blood sugar (FBS), triglyceride (TG), total cholesterol (TC), and high-density lipoprotein-cholesterol (HDL), were related with a higher BMI. Consequently, they exhibited a shorter 6MWD than obese children without cardiometabolic risk clustering [15].

The high prevalence of physical inactivity and sedentary lifestyle in obese children and was found to be associated with decreased heart rate variability and adverse respiratory and cardiovascular effects. Which could be explained the shorter 6MWD than children of normal weight [16]. WHO had announced that a sedentary lifestyle and physical inactivity doubled the risk of numerous health issues, such as cardiovascular disease, high blood pressure, diabetes, obesity, colon cancer, osteoporosis, atherosclerosis, depression, stress, and anxiety, etc. [17].

This study aimed to identify any obesity-related factors, such as metabolic parameters, physical activity, sedentary lifestyle, and cardiac function that influence 6MWT performance in overweight and obese Thai children. We should promote and control all relevant risk factors to improve the quality of life of obese children.

Materials and Methods

Participants

This is a cross-sectional prospective study. We enrolled obese Thai children aged 5 to 15 years with a percentage of weight for height ratio (W/H) of more than 120 at the Obesity clinic, Department of Pediatrics, Naresuan University Hospital from March 3, 2021 to December 31, 2021. Ethics approval for this study was obtained from Naresuan University Institutional Review Board P3- 0167/2563, which followed by Declaration of Helsinki. We started study protocol after participants and/or their parents or legal guardians signed the consent form. The exclusion criteria were as follows: disorders not listed in metabolic syndrome (diabetes, high blood pressure, and dyslipidemia), and uncompleted cardiometabolic data within 6 months of study.

Anthropometric Measurements

Weight and height were measured according to standard procedure, while wearing just light clothing and without shoes. OMRON HBF-375 is a body composition monitor, which uses bioelectrical impedance analysis (BIA) method to measure weight and percentage of fat (%Fat). BMI was computed by dividing weight (kg) by height (m²). The height was determined using a stadiometer.

Cardiometabolic Risk Factor Data

FBS, TG, TC, HDL, and cardiac function (left ventricular ejection fraction; LVEF for reflection of left ventricular function) were collected from medical records.

Physical Activity And Sedentary Time Assessment

The authors conducted face-to-face interviews to collect data using the Global Physical Activity Questionnaire (GPAQ version 2). The Thai version of the questionnaire, with a reliability of 0.67- 0.81, was validated and translated by the Department of Health, Ministry of Public Health [18,19].

Physical Fitness Assessment

The 6MWT was conducted indoors on a flat surface, straight walkway. The participants were seated in a chair near the beginning of the walkway for at least 5 minutes without warming up. Test contraindications include chest discomfort, dyspnea, cramps, headache, ataxia or pallor, resting HR greater than 120 bpm, and BP>99^th by age. Participants were instructed to walk in a straight line for 15 meters before turning around the cone and returning to the starting point. During the test, participants may walk slowly or take a break. The staff may encourage the participants to walk as far as possible. At the end of the test, the total distance walked was measured [9].

Definitions

We classified the severity of obesity as follows: %W/H ≥ 120 is overweight, %W/H ≥ 140 is obese, and %W/H ≥ 200 is morbidly obese. %Fat was compared with normal reference range (P2-85) of age and sex-matched controls [20]. The metabolic risk factor consists of impaired fasting glucose with FBS ≥ 100 mg/dl, and DM with FBS ≥ 126 mg/dl. Dyslipidemia consists of hypertriglyceridemia ≥ 150 mg/dl, hypercholesterolemia ≥ 200 mg/dl, and low HDL <40 mg/dl, according to the Pediatric Obesity Prevention and Treatment practice guideline (3). Normal cardiac function is defined as LVEF ≥ 55% [21]. Physical activity level scoring from GPAQ version 2 with a cut-off value of less than 600 MET-minutes per week indicates physical inactivity. The 6MWD was compared to normal children of the same age and gender; the “Pass test” was defined as a walking distance greater than the 3^rd percentile [22].

Statistical Analysis

Pathare et al. observed that the mean 6MWD in overweight young children is 535.2 with SD=63.623. The error (d) of the calculated sample size is 15 m.

The outcome of the sample size computation in n4 Studies to determine the mean of an infinite population is 70 children. SD. (σ)=63.60 with Error (d)=15.00 and Alpha (α)=0.05.

Categorical data were shown as frequency and percentage. The Shapiro-Wilk W test was used to determine if continuous variable had a normal distribution. Continuous variables are presented as mean ± standard deviations (SD). When comparing the two groups, Chi-square or Fisher’s exact test, independent t-test, and One Way Analysis of Variance with Scheffe post hoc test was utilized. Pearson product moment correlation (r) was used to determine the correlations between 6MWT distance and anthropometric, metabolic syndrome, and physical activity variables. Multiple linear regressions by stepwise method were used to predict 6MWD. Statistical analyses were performed using the STATA version 12.0 software (StataCorp, College Station, TX, USA). P<0.05 were considered significant for all tests.

Results

There were 75 children at the obesity clinic, but only 70 were included in the study, with 49 of them being male. The mean BW and height were 70.81 ± 27.56 kg, 149.86 ± 17.73 cm, respectively. Participants were grouped as follows: overweight 15 (21.4%), obese 41 (60.0%) and morbidly obese 14 (20.0%) (Figure 1). The mean BMI was 31.87 ± 1.74 (kg/m²). The mean %Fat was 30.11 ± 4.28% higher than the normal value of age and sex-matched controls. Table 1 displays the metabolic parameters of the participants. The echocardiography evaluation of heart function revealed a mean LVEF of 63.05 ± 6.04%.

Figure 1: Consort diagram of participants in the study.

Table 1: Anthropometric, metabolic parameters and cardiovascular function of the participants.

The physical activity assessment scores (GPAQ version 2) of all participants were a median of 640 (0-9360) min/week. The mean physical activity assessment scores for overweight, obese, and morbidly obese participants were 760(0-9360), 800(0-7320), and 180(0-7920) min/week, respectively. Forty children (57%) were reported to have sedentary time of >2 hours/day. Thirteen children had sedentary time of >2 hours/day on some days and 17 children had sedentary time of <2 hours /day.

The mean 6MWD in our study was 390 (297-576) m. All participants completed the test with no setbacks. The mean 6MWD for overweight, obese, and morbidly obese was 390(324-453), 400(318-576), and 376(297-417) m, respectively. Most of the participants had a lower 6MWD than the reference value (65 children, 92.9%). There were only 5 obese children (7.1%) who passed the 6MWD test. In the pass group, the mean BMI was 27.52 ± 4.01 and the mean %Fat was 30.78 ± 5.48. All participants in the pass group were obese, and one child exhibited dyslipidemia (hypertriglyceridemia, hypercholesterolemia, and low HDL). Subjects in this group had a normal fasting blood sugar level. No statistically significant difference was found between the two groups (Table 2).

Table 2: 6MWD of the study participants.

When 6MWD was compared with the risk factors of obesity between normal and abnormal levels based on the study’s reference values, we discovered that morbidly obese children (365.07 ± 37.06 m) had a significantly shorter 6MWDs than overweight (392.73 ± 41.02 m) and obese children (408.12 ± 55.16 m) (p=0.022). Subjects with hypercholesterolemia (354.22 ± 34.97 m) had significantly shorter 6MWDs than those with normal cholesterol levels (404.02 ± 50.77 m) (p=0.008). Other risk factors, including age, gender, %Fat, HT, DM, hypertriglyceridemia, HDL, physical activity, and sedentary time, did not significantly impact 6MWD (Table 3).

Table 3: Comparison between 6MWD and risk factors of obesity.

Higher %fat (r=-0.396, P=0.001) and TC (r=-0.386, P=0.001) were found to be correlated with a lower 6MWD. Other risk factors, such as age, BMI, %W/H, TG level, HDL level, FBS, cardiac function, and physical activity, did not exhibit a significant correlation (Table 4, Figure 2).

Figure 2: Graph illustrating the relationship between 6MWD and % Fat / Cholesterol level.

Table 4: Correlation between 6MWD and risk factors of obesity.

Following multiple linear regression analysis (Stepwise Method) to predict 6MWD, we found that %Fat, TG and TC (R² 0.28, p<0.001) could predict 6MWD among obese children (Table 5).

Table 5: Predicted factors of 6MWD among obese children.

Discussion

In this first study on pediatric obesity in Thailand, we found that obese children had a lower age and gender-matched 6MWD than the 3^rd percentile of normal-weight children (92.9%) [22]. W/H, %Fat, and TC were the significant factors related to 6MWD performance in this study.

BMI is a well-established predictor of 6MWT performance in obese children and adolescents [11-14]. Increased BMI necessitates increased energy expenditure, which can limit physical fitness [23]. Since BMI varies with age, our study utilized %W/H to classify the severity of obesity. In Thailand, the severity of obesity was quantified using the W/H ratio derived from the growth curve of Thai children. Therefore, the 6MWD for morbidly obese children (365.07 ± 37.06 m) was shorter than that of the overweight (392.73 ± 41.02 m) and obese children (408.12 ± 55.16 m) (p=0.022), as shown this study.

In terms of body fat percentage (% Fat), we found a negative correlation between 6MWD and %Fat (r=-0.396, P=0.001), which is consistent with two previous studies that indicated adipose tissue in the legs and knees affect functional capacity, resulting in shorter walking distances [24,25]. In our study, the majority of participants had a higher %Fat which may have resulted in a reduction in muscle mass but no statistical difference in 6MWD.

Impaired cardiovascular function and hypertension are the primary risks associated with physical performance. Mahfouz et al. reported that walking distance and coronary flow reserve were reduced in obese adults with hypertension, which was attributed to microvascular dysfunction and arterial stiffness, which consequently limits exercise tolerance [26]. A study of pediatric patients with primary hypertension revealed that their exercise capacity was impaired [27]. However, due to the small sample size, we were unable to confirm this finding in our study.

All of the participants in our study had normal cardiac function reflection from normal LVEF (63.05 ± 6.04%), with observations of nearly lower normal values in morbid obesity (62.71 ± 7.21%), but without statistical significance. This observation finding is consistent with a prior study which demonstrated that obese adolescents had reduced systolic and diastolic cardiac function when compared to normal-weight adolescents who underwent interval aerobic training [28]. We found no correlation between LVEF and 6MWD, which may be due to a less sensitive cardiac function parameter. However, conventional echocardiography can be replaced by a more sensitive technique known as 3D wall motion tracking analysis, which is derived from magnetic resonance imaging scans. This technique can be used to evaluate cardiac remodeling and dysfunction in obese children [29]. Another method of evaluation by echocardiogram is the quantification of epicardial adipose tissue, which has been associated with visceral adipose tissue deposition. Children with obesity had more epicardial fat and impair cardiac function, including diastolic and systolic dysfunction, than children with normal weight [30].

Only TC exhibited a significant negative correlation with 6MWD (r=-0.386, P=0.001) among cardiometabolic risk variables. This is congruent with the findings of the study conducted by Tulika Kuman [31] and Valerio et al., which discovered that obese children with metabolic syndrome had a lower 6MWT performance. Adults with DM have a shorter walking distance than the healthy group [32]. This can be explained by poor glycemic management, which is related with an increase in atherosclerosis in numerous organs, including the lungs, and affects the coronary arteries, resulting in a decrease in blood flow to the heart muscle. A decrease in the heart’s capacity to contract can impede physical activity. In this study, however, obese children with impaired fasting glucose and DM which well-controlled blood sugar had no correlation with 6MWD.

Previous studies on the effects of physical activity and sedentary lifestyle on 6MWT indicated that a sedentary lifestyle is associated with a shorter walking distance, but has no correlation with physical activity [15,33]. Our study did not find a significant correlation between physical activity and sedentary life style and 6MWT, which may be explained by the emerging epidemic of COVID-19 virus. The number of online home schools in Thailand has increased because of the COVID-19 pandemic. As a result, many children have exhibited sedentary behavior and engaged in less physical activities. To determine the level of physical activity, we utilized questionnaires that contained possible recall and desirability biases. In addition to questionnaires, other methods of assessing physical activity, such as muscular strength, were also employed.

Previous research utilized anthropometric data to predict the 6MWD among obese children; age, height, BMI, and hip circumference accounted for 69% of the 6MWD’s variability [34]. In this study, we discovered an equation that utilized both anthropometric and metabolic variables; age, sex, %Fat, TG and TC, with R² of 0.28 and p<0.001 for weight-control intervention follow-up.

Limitation

A key limitation of this research is the small sample size in the Pass group to compare obesity-related factors between the two groups.

Conclusion

W/H, %Fat, and TC were associated with 6MWT performance among obese children aged 5 to 15 years old. Therefore, weight control and a fat-restricted diet are mainly recommended to improve physical performance. For future research, it is suggested that a pre and post diet fat-loss controlled trial be conducted to examine the improvement in physical performance.

Acknowledgements

We are grateful to Mrs. Phavinee Paorod for her work of completely standard 6MWT for all participants.

Conflict Of Interest

The authors declare no conflict of interest.

References

1. World Health Organization (2020) Obesity and overweight.

   [Google Scholar]

2. Yamborisut U (2020) Childhood obesity…challenges facing families and social change. J Nutri Asso Thai 55(1); 17–40.

   [Google Scholar]

3. Ratanachu-ek S, Thaweekul P, Eamopas O, Suthutvoravut U (2014) Obesity. Thai Ped 11-15.

   [Google Scholar]

4. Csige I, Ujvárosy D, Szabó Z, Lőrincz I, Paragh G, et al. (2018) The impact of obesity on the cardiovascular system. J Diabetes Res 2018; 3407306.

   [Crossref] [Google Scholar]

5. Hubert HB, Feinleib M, McNamara PM, Castelli WP (1983) Obesity as an independent risk factor for cardiovascular disease: A 26-year follow-up of participants in the Framingham Heart Study. Circulation 67(5); 968-77.

   [Crossref] [Google Scholar]

6. Korantzopoulos P, Kolettis TM (2005) Obesity and the risk of new-onset atrial fibrillation. JAMA 293(16); 1974; author reply 1975.

   [Crossref] [Google Scholar]

7. Rowland TW (2007) Effect of obesity on cardiac function in children and adolescents: A review. J Sports Sci Med 6(3); 319-26.

   [Google Scholar]

8. Solway S, Brooks D, Lacasse Y, Thomas S (2001) A qualitative systematic overview of the measurement properties of functional walk tests used in the cardiorespiratory domain. Chest 119(1); 256-70.

   [Crossref] [Google Scholar]

9. Paorod P, Chidnok W, Sayasathid J (2020) The effectiveness of cardiac rehabilitation program in open heart surgery patients at Heart Clinic, Naresuan University Hospital. J Royal Thai Army Nurses 21(1); 255-61.

   [Google Scholar]

10. ATS Committee (2002) ATS statement: Guidelines for the six-minute walk test. Am J Respir Crit Care Med 166(1); 111-7.

    [Google Scholar]

11. Morinder G, Mattsson E, Sollander C, Marcus C, Larsson UE (2009) Six-minute walk test in obese children and adolescents: Reproducibility and validity. Physiother Res Int 14(2); 91-104.

    [Crossref] [Google Scholar]

12. Raistenskis J, Sidlauskiene A, Strukcinskiene B, Uğur Baysal S, Buckus R (2016) Physical activity and physical fitness in obese, overweight, and normal-weight children. Turk J Med Sci 46(2); 443-50.

    [Crossref] [Google Scholar]

13. Calders P, Deforche B, Verschelde S, Bouckaert J, Chevalier F, et al. (2008) Predictors of 6-minute walk test and 12-minute walk/run test in obese children and adolescents. Eur J Pediatr 167(5); 563-8.

    [Crossref] [Google Scholar]

14. Geiger R, Willeit J, Rummel M, Högler W, Stübing K, et al. (2011) Six-minute walk distance in overweight children and adolescents: Effects of a weight-reducing program. J Pediatr 158(3); 447-51.

    [Crossref] [Google Scholar]

15. Valerio G, Licenziati MR, Tortorelli P, Calandriello LF, Alicante P, et al. (2018) Lower performance in the six-minute walk test in obese youth with cardiometabolic risk clustering. Front Endocrinol (Lausanne) 9; 701.

    [Crossref] [Google Scholar]

16. De Melo Leite DM, Reis JM, De Barcellos LAM, Pires W, Deresz LF, et al. (2019) Physical inactivity is associated with reduced heart rate variability in exercising eutrophic, type 1 diabetes and obese children. J Phy edu sport 19; 350-7.

    [Crossref] [Google Scholar]

17. Centers of Disease Control and Prevention (2020) The Health effects of overweight and obesity.

    [Google Scholar]

18. Bull FC, Maslin TS, Armstrong T (2009) Global physical activity questionnaire (gpaq): Nine country reliability and validity study. J Phy Act Healt 6(6); 790–804.

    [Crossref] [Google Scholar]

19. Department of Health Ministry of Public Health (2009) Manual for global physical activity surveillance among general population in province by cross-sectional.

    [Google Scholar]

20. McCarthy HD, Cole TJ, Fry T, Jebb SA, Prentice AM (2006) Body fat reference curves for children. Int J Obes (Lond) 30(4); 598-602.

    [Crossref] [Google Scholar]

21. Tissot C, Singh Y, Sekarski N (2018) Echocardiographic evaluation of ventricular function-for the neonatologist and pediatric intensivist. Front Pediatr 6; 79.

    [Crossref] [Google Scholar]

22. Ulrich S, Hildenbrand FF, Treder U, Fischler M, Keusch S, et al. (2013) Reference values for the 6-minute walk test in healthy children and adolescents in Switzerland. BMC Pulm Med 13; 49.

    [Crossref] [Google Scholar]

23. Pathare N, Haskvitz EM, Selleck M (2012) 6-minute walk test performance in young children who are normal weight and overweight. Cardiopulm Phys Ther J 23(4); 12-8.

    [Google Scholar]

24. Correia de Faria Santarém G, de Cleva R, Santo MA, Bernhard AB, Gadducci AV, et al. (2015) Correlation between Body Composition and Walking Capacity in Severe Obesity. PLoS One 10(6); e0130268.

    [Crossref] [Google Scholar]

25. Sternfeld B, Ngo L, Satariano WA, Tager IB (2002) Associations of body composition with physical performance and self-reported functional limitation in elderly men and women. Am J Epidemiol 156(2); 110-21.

    [Crossref] [Google Scholar]

26. Mahfouz RA, Gouda M, Ghareb MS, Galal I (2019) Association between fragmented QRS and exercise intolerance in hypertensive patients: The relation with coronary flow. Blood Press 28(2); 124-130.

    [Crossref] [Google Scholar]

27. Zhang H, Chen Y, Zheng T, Zhang M, Li X, et al. (2022) Factors affecting the exercise capacity in pediatric primary hypertension. Front Pediatr 10; 882223.

    [Crossref] [Google Scholar]

28. Ingul CB, Tjonna AE, Stolen TO, Stoylen A, Wisloff U (2010) Impaired cardiac function among obese adolescents: Effect of aerobic interval training. Arch Pediatr Adolesc Med 164(9); 852-9.

    [Crossref] [Google Scholar]

29. Saltijeral A, Isla LP, Pérez-Rodríguez O, Rueda S, Fernandez-Golfin C, et al. (2011) Early myocardial deformation changes associated to isolated obesity: A study based on 3D-wall motion tracking analysis. Obesity (Silver Spring 19(11); 2268-73.

    [Crossref] [Google Scholar]

30. Cote AT, Harris KC, Panagiotopoulos C, Sandor GG, Devlin AM (2013) Childhood obesity and cardiovascular dysfunction. J Am Coll Cardiol 62(15); 1309-19.

    [Crossref] [Google Scholar]

31. Tulika Kumari, Shyam Chand Choudhary, Kauser Usman, KK Sawlani, Avinash Agrawal, et al. (2019) Study of six minute walk test in patient of metabolic syndrome. Int J Adv Res 7(11); 339-43.

    [Crossref] [Google Scholar]

32. Kuziemski K, Słomiński W, Jassem E (2019) Impact of diabetes mellitus on functional exercise capacity and pulmonary functions in patients with diabetes and healthy persons. BMC Endocr Disord 19(1); 2.

    [Crossref] [Google Scholar]

33. Baillot A, Baillargeon JP, Brown C, Langlois MF (2015) The 6-min walk test reflects functional capacity in primary care and obese patients. Int J Sports Med 36(6); 503-9.

    [Crossref] [Google Scholar]

34. Makni E, Elloumi A, Ben Brahim M, Moalla W, Tabka Z, et al. (2020) Six-minute walk distance equation in children and adolescents with obesity. Acta Paediatr 109(12); 2729-37.

    [Crossref] [Google Scholar]