Relationship of Metabolic Diseases with Physical Activity Depending on Age (original) (raw)

1. Ethical approval

The study was reviewed and approved by the Ethics Committee of the Korea Centers for Disease Control and Prevention (Approval Number 2013-12EXP-03-5C).

2. Subjects

This study was conducted using the second-year survey data of the 6th Korea National Health and Nutrition Examination Survey (KNHANES VI-2) conducted from January to December in 2014. The data used in this study were provided according to the procedures presented in the KNHANES homepage (https://knhanes.cdc.go.kr) [23]. Out of a total of 9,701 respondents aged 19 or older, 2,506 were excluded. Reasons for exclusion included an absence of data regarding physical activity or parameters known to be associated with metabolic diseases, such as blood pressure (BP), waist circumference (WC), body mass index (BMI) and the levels of red blood cells (RBC), hemoglobin (HB), hematocrit (HCT), white blood cells (WBC), platelets (PLT), fasting blood sugars (FBS), triglycerides (TG), high density lipoprotein cholesterol (HDL-C), aspartate aminotransferase (AST), alanine aminotransaminase (ALT), total cholesterol (TC), blood urea nitrogen (BUN), and creatinine (CR). Thus, the data from 7,295 subjects were analyzed. Among these, 382 persons in the normal group and 1,525 persons in the metabolic disease group were analyzed to investigate the relationship between metabolic diseases and physical activity of low- intensity, moderate-intensity and high-intensity according to age using physical, hematological and biochemical parameters.

3. Investigation

The criteria for the diagnosis of metabolic diseases were defined using the guidelines presented in the National Cholesterol Education Program Adults Treatment Panel III; NCEP ATP III [24]. Briefly, the criteria for diagnosis of metabolic diseases were fasting blood glucose (≥110 mg/dL), Asian waist circumference (male ≥90 cm, female >80 cm), blood pressure (systolic/diastolic blood pressure ≥130/85 mmHg), triglycerides (≥150 mg/dL), and high density lipoprotein cholesterol (male <40 mg/dL, female <50 mg/dL) When three or more of the criteria were met, the patient was diagnosed with metabolic disease.

Physical activity was measured using a Korean-version short-form self-report measure of the International Physical Activity Questionnaire developed for the purpose of comprehensive and objective assessment of daily physical activity in everyday life as well as health-related physical activity [25]. The measurement tool was designed to respond to the vigorous physical activity, moderate physical activity, and walking time of 10 minutes or more during the 7 days before the questionnaire survey. Vigorous physical activity was considered activity that makes you breathe much more heavily than usual, and included carrying heavy objects, running, aerobic exercises, climbing, and cycling at a fast speed. Moderate physical activity was defined as activity that led to slightly heavier breath than usual, such as carrying light items, biking at a normal speed, dancing, etc. Walking included walking during recreational activities, sports, exercise, and leisure time, as well as walking at work, home, and while using transportation. The amount of physical activity was converted into the continuous index and categorical index according to the Guidelines for Data Processing and Analysis of the International Physical Activity Questionnaire. The continuous index is for determining the Metabolic Equivalent Task (MET) to compare levels of energy consumption by multiplying the MET level by each activity time. The MET level of each physical activity is 8 for vigorous physical activity, 4 for moderate physical activity, and 3.3 for walking. The categorical index indicates the division of subjects into three levels according to the following criteria. The inactive group, Group 1 (low- intensity), was the group of people who perform the lowest degree of physical activity. This group includes those who do not belong to Group 2 (moderate-intensity) or Group 3 (high- intensity) or do not perform physical activity. Group 2, which was the minimum physical activity group, included people that satisfy any one of the following three criteria: vigorous physical activity for at least 20 minutes per day for at least three days a week; moderate physical activity or walking for at least 30 minutes per day for at least five days a week; physical activity of at least 600 MET-min/week through walking at least 5 days a week or through any combination of moderate or vigorous physical activity. Finally, Group 3, which was the health promoting activity group, included people that satisfied one of the following two criteria: consume at least 1,500 MET-min/week through vigorous activity at least three days per week, or consume at least 3,000 MET-min/week through walking 7 days a week or through any combination of moderate or vigorous physical activity [26]. The amount of physical activity was calculated by measuring the time of vigorous physical activity, moderate physical activity, walking, and sedentary activity in the past 7 days, and then converting them to MET (min/week) values to derive the continuous index and categorical index. The total physical activity score of the continuous score was calculated as the sum of the MET values of walking, moderate-activity, and vigorous activity, while physical activity of less than 10 minutes was considered to be equivalent to no physical activity.

4. Statistical analysis

The data collected in this study were statistically analyzed using the SPSS version 20 program. Descriptive statistics were used to determine the general characteristics of the subjects. ANOVA (analysis of variance) was performed to examine the differences between the normal and metabolic disease groups according to age and the differences depending on physical activity according to age. Correlations between age and metabolic parameters in the normal and metabolic disease groups were confirmed using Pearson’s correlation coefficient. An independent sample t-test was conducted to examine the differences between normal and metabolic disease groups. Multiple regression analysis was conducted to investigate the effects of age and physical activity intensity on parameters of metabolic diseases in the normal and metabolic disease groups.