A simple test to determine a person’s grip strength is a robust predictor of developing metabolic disorders in middle or older age, a cross-continental study has found.
The test locations, demographics and methodology all were selected for a reason.
“Prevalence of chronic disease is highest in the US and China,” says Dr Mark Peterson, assistant professor of physical medicine and rehabilitation at Michigan Medicine and a member of the University of Michigan Global Research, Education and Collaboration in Health and Institute for Healthcare Policy and Innovation. “There’s a dire need to identify midlife predictors of disability and diabetes in both populations.”
Peterson is the lead author on a new study that investigated if normalised grip strength – which is defined as a person’s grip strength divided by their body mass – could serve as a biomarker for both cardiometabolic disease and physical disability in American and Chinese adults.
He teamed up with colleagues from the U-M School of Public Health, Michigan Medicine’s Global REACH, the Institute for Social Science Survey and the National School of Development at Peking University in Beijing, China.
One reason for the study’s geographic focus: “China represents a unique population,” Peterson says. “It’s the world’s largest population of diabetics, which imposes a huge health and economic burden on their entire country.” He adds, “In 2015, China and the US had a combined $320bn in diabetes-related health care costs, according to the International Diabetes Federation. The ageing populations in both countries are growing because of improved medical care of older adults and longer life expectancy. While on one hand that’s great, on the other, it represents two populations that have increasing prevalence estimates of diabetes, cardiovascular health issues and functional impairments. The longer people live with those health issues, the greater the burden is to society.”
The research team used data on middle-aged and older adults from the US National Health and Nutrition Examination Survey from 2011 to 2012 and 2013 to 2014, and the 2011 portion of the China Health and Retirement Longitudinal Study. These surveys were selected because they included measures of muscle strength capacity and the necessary information pertaining to disability and cardiometabolic diseases.
“We wanted to examine grip strength in particular because it is highly associated with overall body strength,” Peterson says. “To asses someone’s grip strength using a handgrip dynamometer takes less than 10 seconds, which makes it extremely attractive to adopt in a clinical or community setting at the population level.”
The research team analysed normalised grip strength for 4,544 U.S. and 6,030 Chinese study participants 50 years of age and older. The study group also had blood samples taken for non-fasting glycated haemoglobin and answered a questionnaire about impairments of functional limitation related to mobility. A subsample of 2,225 adults had fasting measures for glucose, insulin and triglycerides.
Using weighted logistic regression models, the team assessed the association between normalised grip strength and diabetes, hyperglycaemia, hypertriglyceridemia, low HDL cholesterol, hypertension and physical disability. They controlled for age, sex and numerous socio-demographic characteristics.
Perhaps the largest finding of the study was that low normalised grip strength was greatly associated with both cardiometabolic diseases and physical disabilities in middle-age to older adults, both men and women, and in both the US and Chinese populations.
For every 0.05 decrement in normalised grip strength in US and Chinese adults, respectively, there were: 49% and 17% increased odds for diabetes; 46% and 11% increased odds of hyperglycaemia; 15% and 11% increased odds of hypertriglyceridemia; 22% and 15% increased odds of low HDL cholesterol; 19% and 10% increased odds of hypertension; and 36% and 11% increased odds for disability status.
Other highlights from the research team included: prevalence of physical disabilities was higher among older adults (65 years old and older) compared to middle-aged adults (50 years old to 64.9 years old) in both populations; in US adults, physical disability status, obesity and abdominal obesity were more prevalent, and diabetes prevalence was higher with increasing age in US men; in Chinese adults, diabetes prevalence was higher for women than men in both middle-aged and older adults; diabetes was more prevalent in US than Chinese men in both age categories, but more prevalent in Chinese women than US women; and normalised grip strength was higher in Chinese men and women than US men and women in both age categories.
Peterson would like to see these research results translated to the clinical setting.
“We hope these findings illustrate how important a simple grip strength test could be in the clinical setting,” Peterson says. “It’s an easy way to screen and identify people who are at early risk for these health issues.”
Background: Evidence highlights the importance of muscular strength as a protective factor for health and function across aging populations. The purpose of this study was to examine the extent to which low normalized grip strength (NGS) serves as a biomarker for both cardiometabolic disease and physical disability in U.S. and Chinese adults.
Methods: Middle aged and older adults from the U.S. National Health and Nutrition Examination Survey 2011–2012 and 2013–2014 combined surveys (n = 4,544), and the 2011 wave of the China Health and Retirement Longitudinal Study (n = 6,030) were included. Strength was assessed using a handgrip dynamometer, and was normalized to body mass. Weighted logistic regression models were used to assess the association between NGS and diabetes, hyperglycemia, hypertriglyceridemia, low HDL-cholesterol, hypertension, and physical disability status, while controlling for age, sex, and sociodemographic characteristics.
Results: Every 0.05 lower NGS was independently associated with a 1.49 (95% confidence interval [CI]: 1.42–1.56) and 1.17 (95% CI: 1.11–1.23) odds for diabetes; a 1.46 (95% CI: 1.39–1.53) and 1.11 (95% CI: 1.07–1.15) odds of hyperglycemia; a 1.15 (95% CI: 1.07–1.25) and 1.11 (95% CI: 1.08–1.14) odds of hypertriglyceridemia; a 1.22 (95% CI: 1.17–1.27) and 1.15 (95% CI: 1.12–1.18) odds of low HDL-cholesterol; a 1.19 (95% CI: 1.14–1.24) and 1.10 (95% CI: 1.07–1.14) odds of hypertension; and a 1.36 (95% CI: 1.29–1.42) and 1.10 (95% CI: 1.05–1.15) odds for physical disability status in U.S. and Chinese adults, respectively.
Conclusions: NGS was robustly associated with both cardiometabolic disease risk and physical disabilities in U.S. and Chinese aging adults.
Mark D Peterson Kate Duchowny Qinqin Meng Yafeng Wang Xinxin Chen Yaohui Zhao