Getting a grip on health norms: Handgrip strength

Now, a groundbreaking study led by the University of South Australia and conducted in collaboration with 140 authors across the globe, has created the world’s largest and most geographically comprehensive international norms for handgrip strength, enabling global peer-comparison, health screening and surveillance across the adult lifespan.

Published in The Journal of Sport and Health Science today, the new norms are based on 100 unique observational studies representing 2.4 million adults aged 20 to 100+ years, from 69 countries (representing six of the seven continents, 17 of 22 United Nations’ geographical subregions, and 71% of the world’s population).

It is the first time that norms have been reported for handgrip strength across different age groups and sexes at the international level.

Handgrip strength, or isometric grip, is measured via a handgrip dynamometer which is gripped and squeezed to record the maximum force a person can produce over a few seconds.

A person with low handgrip, or low muscle strength, has a higher risk of death from all causes and cardiovascular disease as well as a higher incidence of physical disability.

The new study has established a percentile framework that ranks strength. Adults below the 20^th percentile are considered to have ‘low’ strength; those between 20-39^th percentiles have ‘somewhat low’ strength; those in the 40-59^th percentiles have ‘moderate’ strength; those in the 60-79^th percentiles have ‘somewhat high’ strength; and those at or above the 80^th percentile having ‘high’ strength.

Importantly, norms can be used to monitor healthy aging by examining changes in strength over time.

Lead researcher Professor Grant Tomkinson says the new norms will help clinicians better identify people who may be at risk of poor health and in need of interventions.

“Muscle strength, which reflects the ability of the muscles to produce force maximally, is a powerful biomarker of current and future health,” Prof Tomkinson says.

“A good general measure of overall muscle strength is how hard you can grip.

“Grip strength improves a little throughout early adulthood, peaks between age 30 and 39, and then drops off as people age, especially in late adulthood.

“By establishing international handgrip norms through a reference population, we can determine how well someone compares to their peers of the same age and sex, and quickly identify people who need intervention.

“But until now, there has been no international markers by which to compare or benchmark.

“Our research has established robust international norms that enable clinicians and exercise professionals to interpret and relate results in a percentile ranking. For example, adults below the 20^th percentile are considered to have ‘low’ strength, those between 20-39^th percentiles have ‘somewhat low’ strength, and so on as the scale progresses.

“So, what we have developed is an international guideline and benchmark that enables clinicians to compare and track muscle strength — and therefore potential health risks — across the adult lifespan.”

The new norms will enable standardised grip strength test results for cross- and within-country comparisons, to identify trends over time, monitor improvements and evaluate the effectiveness of implemented public health policies. They will also facilitate individual feedback, advice, and health interventions for those at risk.