- Open Access
The association among three aspects of physical fitness and metabolic syndrome in a Korean elderly population
© Hwang and Kim. 2015
- Received: 23 July 2015
- Accepted: 18 November 2015
- Published: 12 December 2015
The purpose of current study is to evaluate the association between physical fitness level and the prevalence of metabolic syndrome (MS) in a Korean elderly population.
A cross-sectional study measuring physical fitness and components of MS in a health promotion center of a general hospital for routine health check-ups. A total of 227 subjects >60 years old agreed to participate. A lifestyle questionnaire that included cigarette smoking, alcohol consumption, and physical activity was checked. Body weight, height, blood pressure, fasting glucose, total cholesterol, triglycerides, high density lipoprotein-cholesterol, low density lipoprotein-cholesterol, C-reactive protein, and glycated hemoglobin were measured. Muscular strength was assessed by measuring grasping power. Muscular endurance was evaluated using a sit-up test. Cardiopulmonary fitness was assessed via the Tecumseh step test (measuring hear rates at 1 min post-exercise).
The highest tertile muscular endurance group (sit-ups >15 in men, >10 in women) was 0.37 times less likely to have MS [95 % confidence interval (CI) 0.17–0.84; p = 0.036] compared to that in the lowest tertile group (<11 in men, 0 in women), and the highest tertile in the cardiopulmonary fitness group (heart rate at rest >91/min in men, >92/min in women) was 2.81 times more likely to have MS (95 % CI 1.27–6.18; p = 0.038) compared to that in the lowest tertile group (<81/min in men, <80/min in women).
Cardiopulmonary fitness and muscular endurance were related to MS in a Korean elderly population after adjusting for age, sex, current smoker, current alcohol drinking, and physical activity. Older adults should be encouraged to increase their cardiopulmonary fitness and muscular endurance.
- Physical fitness
- Metabolic syndrome
- Cardiopulmonary fitness
- Muscular endurance
Metabolic syndrome (MS) is the term given to a group of interrelated risk factors of metabolic origin that appear to directly promote the development of cardiovascular diseases . MS is strongly associated with type 2 diabetes mellitus . The prevalence of MS are increasing rapidly and a study recently reported that the prevalence of MS is 22.1 % in Korean males and 27.8 % in Korean females . Thus, preventing MS has become an important issue.
In general, people with MS have low physical performance, and high level physical fitness could be helpful to prevent the development of chronic diseases independent of adiposity in youth and adults [4, 5]. Physical fitness is defined as the ability to carry out work necessary for muscle exercise . It is generally considered “the ability to perform daily tasks without fatigue” . However, most studies that have demonstrated the relationship between physical fitness and MS were performed with young Caucasian adults, and relatively few studies have been conducted among the Asian elderly population. Therefore, the purpose of this study was to evaluate the association between physical fitness level and the prevalence of MS in a Korean elderly population.
This cross-sectional study was explained to a Korean elderly population who visited a health promotion center of one general hospital in Gyeonggi province for routine health check-ups between November 2008 and February 2009, and 227 (121 men and 106 women) subjects >60 years old agreed to participate. Written informed consent was obtained from all subjects. This study was approved by the ethics review committee of a hospital.
Life style measurements
All subjects completed a lifestyle questionnaire that included questions about cigarette smoking, alcohol consumption, and physical activity. A smoking habit was defined as currently smoking cigarettes. Drinking more than 70 g/week was defined as alcohol drinking. Age and sex was checked by resident registration number. Current medical diseases such as diabetes mellitus and hypertension were collected from medical records. Subjects who had history of chronic liver disease or chronic renal disease were not included in this study.
Body weight (kg) and height (cm) were measured using JENIX automatic measuring equipment (Garden Jenix, Seoul, Korea) while subjects were wearing light-weight clothing or a hospital gown without shoes. Body mass index (BMI, kg/m2) was calculated as weight (kg) divided by height squared (m2), and waist circumference (WC, cm) was measured midway between the lowest rib and the iliac crest using a Gullick II tape with subjects in the standing position at the end of a normal expiration. All anthropometric measurements were performed by a single researcher.
Blood pressure (BP) and blood assay
BP was measured using a mercury sphygmomanometer (Hico, Tokyo, Japan) when the subjects were relaxed. All participants were asked to rest for 10 min in the sitting position prior to the measurement. Blood samples were collected for biochemical tests after overnight fasting (>12 h), and serum concentrations of fasting glucose, total cholesterol (TC), triglycerides (TG), high density lipoprotein-cholesterol (HDL-C), low density lipoprotein-cholesterol (LDL-C), and C-reactive protein were measured using an ADVIA 1650 Chemistry System (Siemens, Tarrytown, NY, USA). Glycated hemoglobin (HbA1C) was evaluated using a HLC-723GHb instrument (TOSOH, Siba, Minaoto-ku, Japan).
Physical fitness measurements
Muscular strength was assessed by measuring grasping power with a digital dynamometer (TKK 5101 Grip-D; Takey, Tokyo, Japan). The subject sat with shoulders adducted, elbows flexed, and forearms at the mid-position. The second joint was used to position the dynamometer, and the handle was adjusted according to finger length. The subject performed the test twice, allowing a 3 min rest period between measurements. The mean value of two trials was scored. This test is valid and reliable .
Muscular endurance was assessed using a sit-up test. The participants lay on sit-up equipment and performed sit-ups with their feet attached to the equipment’s foot holders. One sit-up was counted when the participants sat up so that their elbows touched their thighs, and they had returned to the supine position and both shoulders touched the equipment. The number of sit-ups performed in 30 s was recorded.
Cardiopulmonary fitness was assessed using the Tecumseh step test. Based on the guidelines for the Tecumseh step test, subjects performed 24 steps/min, maintaining a constant stepping rate on a 20.3 cm high step for 3 min. To help maintain a constant stepping rate, a metronome was used, and an assistant was present. The subjects wore HR monitors (FS3C; Polar Electro, Lake Success, NY, USA), and HRs were recorded prior to exercise and at each 1 min interval during the exercise session. HR was also measured for 1 min during the recovery phase. Participants with higher cardiopulmonary fitness would have lower HRs at 1 min post-exercise than those with lower cardiopulmonary fitness .
Physical activity (PA) assessment
Definition of MS
According to the National Cholesterol Education Program Adult Treatment Panel III (NCEP ATP III) standard, MS is diagnosed when a person has three or more components from the following list: abdominal obesity (WC >102 cm for males, >88 cm for females), high fasting glucose level (>100 mg/dL, fasting or taking diabetic medications), high blood pressure (systolic blood pressure >130 mm Hg or diastolic blood pressure >85 mm Hg or taking antihypertensives), high TG (>150 mg/dL), and low level of HDL-C (<40 mg/dL for males, <50 mg/dL for females) . Due to a smaller body size, the Asian version of the modified NCEP ATP III definition was employed (WC: >90 cm in males, >80 cm in females) .
The t test or Chi square test was used to compare differences between subjects with MS and subjects without MS. A non-normally distributed variable such as triglyceride was analyzed after log transformation. A partial correlation analysis was carried out to identify the relationship between physical fitness and components of MS. Each physical fitness item was categorized into tertiles to compute odds ratios (ORs) and 95 % confidence intervals (CIs) for MS. A logistic regression analysis was performed to assess the associations between physical fitness and MS after adjusting for age, sex, current smoker, current alcohol drinking, and physical activity. All statistical analyses were conducted using SPSS 17.0 (SPSS Inc., Chicago, IL, USA), and a p value <0.05 was considered significant.
Baseline characteristics of the subjects according to metabolic syndrome (MS)
Without MS (n = 142)
With MS (n = 85)
66.9 ± 5.3
66.8 ± 5.3
Body mass index, kg/m2
23.5 ± 2.4
26.0 ± 2.6
Waist circumference, cm
79.5 ± 7.0
86.3 ± 6.6
Systolic blood pressure, mmHg
126.6 ± 14.6
133.7 ± 12.3
Diastolic blood pressure, mmHg
76.7 ± 9.8
79.1 ± 8.4
98.9 ± 17.6
113.2 ± 23.6
5.80 ± 0.72
6.12 ± 0.72
Total cholesterol, mg/dL
193.3 ± 32.6
192.6 ± 35.3
109.2 ± 50.4
176.9 ± 92.1
52.1 ± 12.5
42.6 ± 9.4
120.4 ± 28.4
123.0 ± 32.1
C-reactive proteina, mg/dL
0.18 ± 0.41
0.18 ± 0.29
Total Physical activitya, METs
2192.2 ± 3130.8
1884.1 ± 1980.2
Partial correlation analysis between physical fitness and the components of metabolic syndrome
HR 1 min post exercise
Systolic blood pressure
Diastolic blood pressure
HR 1 min post exercise
Odd ratios for metabolic syndrome according to physical fitness
p for trend
HR 1 min post exercise
This study reported the the association of physical fitness and prevalence of metabolic syndrome in selected population, in other words, elderly subjects and Korean population with measuring complete physical fitness.
MS is very prevalent in many countries worldwide. Many cross-sectional studies support an inverse association between physical activity and MS, but few studies have been conducted on the association between physical fitness and MS. Furthermore, most of those studies focused on cardiopulmonary fitness using a cycle ergometer or treadmill test. The present study checked physical fitness from three aspects: muscular strength measuring grasping power, muscular endurance using a sit-up test, and cardiopulmonary fitness by the Tecumseh step test.
BMI, WC, diabetes mellitus, hypertension, fasting glucose, HbA1c, and TG were higher or more frequent in the MS group, whereas HDL-C was lower, as these parameters are included in the diagnostic criteria of MS. TC, LDL-C, and physical activity were not different between subjects with MS and those without MS. Physical activity levels were not different between the MS and non-MS groups.
Previous studies [14–20] on cross-sectional associations between physical fitness and MS have reported a significant inverse association between fitness and the prevalence of MS. Carnethon et al. reported low fitness (<20th percentile) were three- to sixfold more likely to develop diabetes, hypertension, and the metabolic syndrome than participants with high fitness (≥60th percentile) . In Quebec family study, fitness was negatively associated with most individual components of the metabolic syndrome, except HDL-cholesterol . Prevalence of the MS was markedly lower across progressively higher levels of cardiorespiratory fitness(CRF) . A dose–response association was present between the number of components of the MS and exercise capacity . individuals with lowest CRF compared to those with highest CRF had 3.1- and 11.8-fold higher risk of having 2 and ≥3 MS components, respectively . All of these studies checked cardiopulmonary fitness via a treadmill test or cycle ergometer as a measure of physical fitness. However, these methods require time, qualified personnel, and resources. The Tecumseh step test used in the current study is a relatively quick and easy test for measuring cardiopulmonary fitness and the correlation between the results of the 3 min step test and maximum oxygen consumption has been validated . In the present study, cardiopulmonary fitness assessed by the Tecumseh step test was negatively associated with MS. Cardiopulmonary fitness is the ability to exercise continuously for extended periods without tiring while working the heart and lungs. Increased cardiopulmonary fitness is known to reduce the risk of cardio-metabolic diseases [19–23]. Low cardiopulmonary fitness is an independent predictor of all-cause and cardiovascular disease mortality. Cardiopulmonary fitness is considered to affect these comorbidities by regulating cardiac output and blood pressure .
The strength of the present study is that we checked two additional aspects of physical fitness such as muscular strength and muscular endurance. Grasping power is proportional to skeletal muscle mass, which could be related to body mass in general and could explain the positive correlation between grasping power and BMI and WC. Although muscular strength was not associated with MS in the present study, another study showed that lower grip strength was significantly associated with increased odds of having MS . The number of sit ups on the sit-up test was positively correlated with fasting glucose. Insulin resistance is thought to be associated with central obesity. The relationship between the sit-up test and MS could be due to central adiposity . Thus, measures of muscular endurance could be a marker for the risk of MS.
Several limitations of the present study should be recognized. First, the cross-sectional nature of this study precluded our ability to identify any cause-effect relationships. Second, self-reported physical activity is almost always substantially higher than that measured objectively, and, therefore, it might lead to an attenuation of the effect of physical activity on MS in the elderly. Third, the prevalence of MS in this study (36 % for male and 40 % for female) were much higher than those of MS in national representative data (22.1 % in Korean males and 27.8 % for females) 0.3 The discrepancy could be due to the fact that the study sample used in the current study was older adults. Also, there could be a selection bias since the study sample was selected from only one general hospital in Gyeonggi province, the most populous province of Korea, although we enrolled all elderly who who visited for routine health check-ups and agreed to participate. Fourth, muscular strength is validated in the adolescent, not the older adults.
Cardiopulmonary fitness and muscular endurance were related to MS in a Korean elderly population after adjusting for age, sex, current smoker, current alcohol drinking and physical activity. In conclusion, not only cardiopulmonary fitness but also strengthening muscle should be recommended in practice, services or health care policy, especially for elderly.
HJH participated in the design of the study and performed the statistical analysis. SHK conceived of the study, and participated in its design and coordination and helped to draft the manuscript. Both authors read and approved the final manuscript.
The authors declare that they have no competing interests.
Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
- Grundy SM, Brewer HB Jr, Cleeman JI, et al. Definition of metabolic syndrome: report of the National Heart, Lung, and Blood Institute/American Heart Association conference on scientific issues related to definition. Circulation. 2004;109:433–8.View ArticlePubMedGoogle Scholar
- Hanson RL, Imperatore G, Bennett PH, et al. Components of the metabolic syndrome and incidence of type 2 diabetes. Diabetes. 2002;51:3120–7.View ArticlePubMedGoogle Scholar
- Kim MH, Kim MK, Choi BY, et al. Prevalence of the metabolic syndrome and its association with cardiovascular disease in Korea. J Korean Med Sci. 2004;19:195–201.PubMed CentralView ArticlePubMedGoogle Scholar
- Ferreira I, Twisk JW, van Mechelen W, et al. Development of fatness, fitness, and lifestyle from adolescence to the age of 36 years: determinants of the metabolic syndrome in young adults: the amsterdam growth and health longitudinal study. Arch Intern Med. 2005;165:42–8.View ArticlePubMedGoogle Scholar
- LaMonte MJ, Barlow CE, Jurca R, et al. Cardiorespiratory fitness is inversely associated with the incidence of metabolic syndrome: a prospective study of men and women. Circulation. 2005;112:505–12.View ArticlePubMedGoogle Scholar
- Bouchard C, Shephard RJ, Stephens TH. Physical activity, fitness and health. A consensus of current knowledge. Champaign, IL: Human Kinetics. 1993.Google Scholar
- Caspersen CJ, Powell KE, Christenson GM. Physical activity, exercise and physical fitness: definitions and distinctions for health-related research. Public Health Rep. 1985;100:126–31.PubMed CentralPubMedGoogle Scholar
- Espana-Romero V, Ortega FB, Vicente-Rodriguez G, et al. Elbow position affects handgrip strength in adolescents: validity and reliability of Jamar, DynEx, and TKK dynamometers. J Strength Cond Res. 2010;24:272–7.View ArticlePubMedGoogle Scholar
- Santo AS, Golding LA. Predicting maximum oxygen uptake from a modified 3-minute step test. Res Q Exerc Sport. 2003;74:110–5.View ArticlePubMedGoogle Scholar
- Craig CL, Marshall AL, Sjostrom M, et al. International physical activity questionnaire: 12-country reliability and validity. Med Sci Sports Exerc. 2003;35(8):1381–95.View ArticlePubMedGoogle Scholar
- Oh JY, Yang YJ, Kim BS, et al. Validity and reliability of Korean version of international Physical Activity Questionnaire (IPAQ) short form. J Korean Acad Fam Med. 2007;28:532–41.Google Scholar
- National Cholesterol Education Program/National Heart, Lung and Blood Institute/National Institute of Health. Third report of the expert panel on detection, evaluation, and treatment of high blood cholesterol in adults (adult treatment panel III). Bethesda: National Heart, Lung and Blood Institute/National Institute of Health. 2002.Google Scholar
- Tan CE, Ma S, Wai D, et al. Can we apply the national cholesterol education program adult treatment panel definition of the metabolic syndrome to Asians? Diabetes Care. 2004;27:1182–6.View ArticlePubMedGoogle Scholar
- Carnethon MR, Gidding SS, Nehgme R, et al. Cardiorespiratory fitness in young adulthood and the development of cardiovascular disease risk factors. JAMA. 2003;290:3092–100.View ArticlePubMedGoogle Scholar
- Boule NG, Bouchard C, Tremblay A. Physical fitness and the metabolic syndrome in adults from the Quebec Family Study. Can J Appl Physiol. 2005;30:140–56.View ArticlePubMedGoogle Scholar
- Farrell SW, Cheng YJ, Blair SN. Prevalence of the metabolic syndrome across cardiorespiratory fitness levels in women. Obes Res. 2004;12:824–30.View ArticlePubMedGoogle Scholar
- Wong CY, O’Moore-Sullivan T, Fang ZY, et al. Myocardial and vascular dysfunction and exercise capacity in the metabolic syndrome. Am J Cardiol. 2005;96:1686–91.View ArticlePubMedGoogle Scholar
- Orakzai RH, Orakzai SH, Nasir K, et al. Association of increased cardiorespiratory fitness with low risk for clustering of metabolic syndrome components in asymptomatic men. Arch Med Res. 2006;37:522–8.View ArticlePubMedGoogle Scholar
- Blair SN, Kohl HW 3rd, Paffenbarger RS Jr, et al. Physical fitness and all-cause mortality: a prospective study of healthy men and women. JAMA. 1989;262:2395–401.View ArticlePubMedGoogle Scholar
- Sandvik L, Erikssen J, Thaulow E, et al. Physical fitness as a predictor of mortality among healthy, middle-aged Norwegian men. N Engl J Med. 1993;328:533–7.View ArticlePubMedGoogle Scholar
- Blair SN, Kohl HW 3rd, Barlow CE, et al. Changes in physical fitness and all cause mortality: a prospective study of healthy and unhealthy men. JAMA. 1995;273:1093–8.View ArticlePubMedGoogle Scholar
- Erikssen G, Liestol K, Bjornholt J, et al. Changes in physical fitness and changes in mortality. Lancet. 1998;352:759–62.View ArticlePubMedGoogle Scholar
- Duncan GE. Exercise, fitness, and cardiovascular disease risk in type 2 diabetes and the metabolic syndrome. Curr Diab Rep. 2006;6:29–35.View ArticlePubMedGoogle Scholar
- Armstrong K, Rakhit D, Jeffriess L, et al. Cardiorespiratory fitness is related to physical inactivity, metabolic risk factors, and atherosclerotic burden in glucose-intolerant renal transplant recipients. Clin J Am Soc Nephrol. 2006;1:1275–83.View ArticlePubMedGoogle Scholar
- Sayer AA, Syddall HE, Dennison EM, et al. Grip strength and the metabolic syndrome: findings from the Hertfordshire Cohort Study. QJM. 2007;100:707–13.PubMed CentralView ArticlePubMedGoogle Scholar
- Ferrannini E, Haffner SM, Mitchell BD, et al. Hyperinsulinemia: the key feature of a cardiovascular and metabolic syndrome. Diabetologia. 1991;34:416–22.View ArticlePubMedGoogle Scholar