Poor Health-related Physical Fitness Performance Increases the Overweight and Obesity Risk in Elderly People From Taiwan

Background The purpose of the present study was to investigate the associations between health-related physical tness performance and overweight/obesity risk among Taiwanese healthy older adults. Methods A secondary dataset from the nationwide survey with 21,630 data was applied in this study. Demographic characteristics, life habits, perceived health status, anthropometric assessments, and health-related physical tness measurements from this dataset were analyzed using the chi-square test, one-way analysis of variance, and logistic regression analysis. Results The results indicated that overweight and obesity signicantly reduced health-related physical tness performance in the Taiwanese older adult population. In particular, the upper extremity muscular endurance scores of older adults with poor activity and physical tness scores revealed obesity as a critical indicator of health-related physical tness performance. precisely cross-sectional study was conducted to analyze various physical tness measurements with OW and obesity risks among healthy older adults in Taiwan. Reviewed data derived from Taiwan's National Physical Fitness Survey Databases (THPFSD 2014–2015) charged by Taiwan's Sports Administration, Ministry of Education. All data were recruited using convenience sampling from 46 examination stations at 20 cities or counties in Taiwan. Each subject lled out demographic characteristics and life habit questionnaires and the measured resting heart rate and blood pressure for safe preliminary screening before conducting physical tness measurements. Finally, we assayed the questionnaire and physical tness data among 21,630 older adults aged higher or equal in the present study. The protocol, study design, data, and CS2-16114. their health status. Future studies are suggested to proceed with these aspects. Third, due to cross-sectional study design was applied, there is no cause and effect relationship can be guaranteed. Future studies may conduct longitudinal studies to have a better understanding of this relationship.


Background
The increasing prevalence of obesity is a public concern in many developing and developed countries. Obesity increases the risk factors of various diseases, such as hypertension, heart diseases, cancer, and type II diabetes [1,2]. Studies have indicated that obesity results in declining health-related physical tness performance, including muscular endurance, muscular strength, exibility, and cardiorespiratory capacity [3][4][5]. This decline reduces the quality of life and increases countries' economic and social burden [6].
Aging has also been discovered to reduce health-related physical tness performance. In the aging process, people's muscular strength, muscle mass, cardiorespiratory tness, and physical activity deteriorate while their body fat percentage increases, resulting in a high prevalence of overweight (OW) and obesity in older adults [7,8]. Furthermore, studies have revealed the phenomenon of muscle mass reducing as older adults' body fat increases-this is known as sarcopenic obesity [5,9]. Sarcopenic obesity may result in declining health-related physical tness performance, which reduces people's quality of life [5]. One study indicated that enhance one's health-related physical tness performance is signi cantly reducing the incidence of cardiovascular diseases [10]. Therefore, understanding the relationship between physical tness and obesity in older adults is vital.
The literature on obesity and health-related physical tness performance in the elderly population is sparse. Most studies on these topics discuss the in uence of obesity on the said performance of children or adolescents. Therefore, obesity and health-related physical tness performance in older adults are crucial topics that warrant signi cant sample analyses. The present study aimed to determine the associations of health-related physical tness performance with OB and obesity risk among healthy older adults in Taiwan.

Study design and participants
A cross-sectional study was conducted to analyze various physical tness measurements with OW and obesity risks among healthy older adults in Taiwan. Reviewed data derived from Taiwan's National Physical Fitness Survey Databases (THPFSD 2014(THPFSD -2015 charged by Taiwan's Sports Administration, Ministry of Education. All data were recruited using convenience sampling from 46 examination stations at 20 cities or counties in Taiwan. Each subject lled out demographic characteristics and life habit questionnaires and the measured resting heart rate and blood pressure for safe preliminary screening before conducting physical tness measurements. Finally, we assayed the questionnaire and physical tness data among 21,630 older adults aged higher than or equal 65 years between October 2014 and March 2015 in the present study. The protocol, study design, data, and survey were reviewed and approved by The Institutional Review Board, Chung Shan Medical University Hospital. The approved number is CS2-16114.

Data collection
The well-trained research assistant and nurses completed a face-to-face interview and physical examination. The questionnaire's data included demographic characteristics such as age, sex, education, and monthly income, and life habits such as smoking, betel-nut chewing, and dieting, as well as perceived health status, were recorded. Education level was divided into three categories: elementary or lower, junior or senior school, and college or higher. Monthly income level was divided into three categories: 20,000 NTD (New Taiwan Dollar) or under, between 20,001-40,000 NTD, and 40,001 NTD or above. Marital status was divided into three categories: married, never married, and divorced/separated/widowed. Health status was divided into three categories: excellent or good, fair, and very bad or poor. Smoking was divided into three categories: never, current, and former. Chewing betel nut was divided into three categories: never, current, and former. This questionnaire was developed by Taiwan's Sports Administration, Ministry of Education, and has implemented in the annual nationwide survey for years. The same questionnaire has also reported and published previously [11].

Anthropometric assessment
In this study, anthropometric assessments, including body weight (kg), height (m), waist, and hip circumference (WC & HC). All participants were required to remove their shoes and heavy clothes during measuring if any. Body mass index (BMI) of the participants then calculated (kg/m 2 ). The WC and HC were measured to the nearest 0.1 cm by a soft measuring tape at the natural waist and greater trochanter level. Thus, it allowed the present study to calculate the waist-to-hip ratio (WHR). The cut-off values for BMI were suggested by the Taiwanese Ministry of Health and Welfare (MOHW). The cut-offs for underweight (UW), normal weight (NW), OW, and obese (OB) are 18.5, 24, and 27 kg/m 2 [12].
Health-related physical tness measurements 2-minute step test, 30-second arm curl, 30-second chair stand, back scratch, chair sit-and-reach, one-leg stance with eye open, and 8-foot up-and-go were measured to access the functional capacity among the participants. These measurements were representing individual aerobic endurance, muscle strength, muscle endurance, exibility, and balance. The protocol of these measurements was conducted by quali ed examiners who have certi ed from the o cial training courses. Besides, the protocol of these measurements was mainly performed by the Serious Fitness Test (SFT) manual [13], except the oneleg stance with eye open was performed according to the previous approach [14].
The participants were informed of the measuring protocol with a 10 minutes warm-up, led by the examiners before the measurements. All participants were allowed to have the interval breaks until they are ready for the next section. The outcomes of these measurements were classi ed respectively into four quartiles for further analysis.

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The Statistical Analysis System (SAS) software package (Version 9.4, SAS Institute Inc., Cary, NC) was used for data analysis. Chi-square tests and one-way analysis of variance (ANOVA) were used to analyze demographic characteristics and health-related physical tness measurements among groups of participants. Tukey's post hoc tests were applied for those signi cant differences has found (p < 0.05) in order to determine the sequences among the groups. Further, logistic regression analyses were conducted to estimate the OW and obesity risks (odds ratios; ORs) with the health-related physical tness measurement quartiles. The potential confounders also adjusted the regression models. All values were expressed as means ± standard deviation (SD), or the percentage (frequency). The signi cant level within each analysis was p < 0.05 to reject the null hypothesis and with a con dence interval (CI) of 95%. Results 21,630 participants with complete data were included from Taiwan's National Physical Fitness Examination Survey Databases (35.38% of men). Demographic characteristics and anthropometric variables are presented in Table 1. The highest proportion of general obesity status was NW (41.69%). All participants were divided into trichotomy groups as NW, OW, and OB by gender. The signi cant differences were shown between NW, OW, and OB groups on all relevant variables except men's marital status (p = 0.481). In contrast, there were signi cant differences between NW, OW, and OB groups on all relevant variables except smoking status in women (p = 0.236).  Table 2 presented the comparison of inter-group differences by various health-related physical tness measurements. All the general obesity status groups were signi cant differences in all the health-related physical tness measurements in both men and women, and OB individuals got the lowest grade of all measurements except the 30-second arm curl test.

Discussion
This study employed large-sample national survey data to discuss the relationship between functional physical tness and obesity risks in older adults. The results indicated that OW and obesity signi cantly reduced the health-related physical tness performance in a Taiwanese older adult population. In particular, the upper extremity muscular endurance scores of older adults with poor activity and physical tness scores revealed obesity to be a critical indicator of health-related physical tness performance. These ndings are critical for establishing health care policies in the future.
Obesity is a key in uential factor in the exibility in older adults in Taiwan. OW and obesity are critical indicators of higher percentages of body fat and visceral fat, resulting in aggravated low-grade in ammation and osteoarthritis, further affecting the exibility in older adults [15,16]. Studies have veri ed that aging decreases the exibility [17]. In particular, the BMI and exibility in female older adults exhibit a signi cant negative correlation, which indicates that OW and obesity reduce the exibility [18][19][20]. This study used interference factors to adjust and compute odds ratios; the ndings revealed that in OW and OB older adults in Taiwan, different obesity levels signi cantly in uenced their chair sit-and-reach and back scratch test scores. This indicated that obesity levels had a signi cantly negative effect on older adults' exibility, a conclusion consistent with previous studies.
Besides, this study discovered that obesity had different in uences on upper extremity muscular endurance and lower extremity muscle strength and endurance in older adults. This study adjusted the research data for age, WC, education, monthly income, marital status, self-reported health status, smoking status, and betel nut chewing status for the in uences on lower extremity muscle strength and endurance. Our ndings revealed that older adults with NW had more favorable lower extremity muscular strength (8 Foot Up-and-Go test) and muscular endurance (30-second chair stand test) scores.
However, the scores for OW and OB older adults did not exhibit signi cant differences. This result is consistent with that of the previous study [21]. In this study, Brady (2014) measured participants' leg press strength and divided the scores by their lower extremities' weight to quantify their muscle quality. The results revealed that healthy older adults' muscle quality was signi cantly higher than that of OW and OB older adults, with no signi cant differences in muscle quality observed between the latter two [21]. This result is consistent with that of the present study, namely that the 8 foot up-and-go and 30second chair stand test results of OW and OB older adults did not exhibit signi cant differences. Therefore, BMI is a viable indicator for predicting older adults' obesity level, but cannot serve as an indicator for predicting their lower extremity muscular strength and endurance. A possible reason for this result may be older adults' different body densities because BMI values cannot wholly re ect the proportions of an individual's muscles and fat [22].
Unlike the results on lower extremities, this study revealed that obesity signi cantly in uenced older adults' upper extremity muscular endurance. This was particularly true for OW female older adults and the OB population. After conducting logistic regression and making adjustments for potential confounders, the present researchers discovered that OW and obesity posed higher risks to the rst and second levels in this study; by contrast, the other two intervals did not exhibit signi cant differences. These results indicated that obesity and OW's risk is signi cantly lower for older adults with more favorable upper extremity muscular endurance. Therefore, physical activity interventions can enhance exercise capabilities, signi cantly reducing the adverse effects of obesity on upper extremity muscular endurance.
The results revealed that for older adults in Taiwan, the 2-min step test results of OW and OB older adults are signi cantly worse than those of older adults of NW. However, after being adjusted by interference factors, this phenomenon was only true for OW male patients who had stepped on a ladder < 73 times. This result indicated that weight in uences male older adult populations with poor aerobic physical tness, but not women or OB populations. This nding is inconsistent with studies that have discovered the in uence of obesity on aerobic exercise capabilities [5,10]. However, this inconsistency could be caused by differences in participants' age, sex, and ethnicity, interference factors, or statistical power value. Future studies can discuss the relationship between other aerobic physical tness indicators and OW and obesity.
The strength of the present study was using a representative database. Although the potential confounders were considered throughout the analysis, some limitations should be addressed. First, the data used in this study was mainly included Chinese Taiwanese population. Future studies should investigate the populations from different races, lifestyles and cultures, social-economic backgrounds, etc. Second, the use of a secondary database limited the possibility of discussing other elder-related factors, such as chronic diseases, dietary and nutrition, and living status. These factors critically in uence the elder's quality of life as well as their health status. Future studies are suggested to proceed with these aspects. Third, due to cross-sectional study design was applied, there is no cause and effect relationship can be guaranteed. Future studies may conduct longitudinal studies to have a better understanding of this relationship.

Conclusion
In conclusion, this study discovered that OW and obesity signi cantly reduced the older adult population's health-related physical tness performance in Taiwan. In particular, they reduced the muscular endurance scores for populations with poor physical activity and physical tness scores. Furthermore, the ndings revealed that BMI to be a classi cation standard for OW and obesity. However, it was incapable of precisely predicting the effects of obesity on lower extremity muscular strength, muscular endurance, and aerobic physical tness performance. Future studies can use muscle quality or body fat classi cation as predictors of obesity in older adults, which could more precisely portray the relationship between obesity and health-related physical tness performance. Center of Sports for All, Sport Administration, Ministry of Education in Taiwan. All consents obtained from the study participants were written prior the data collection. This study's design and analysis procedure was approved by The Institutional Review Board, Chung Shan Medical University Hospital (CS2-16114).

Consent for publication
Not applicable.