August 1, 2023 – Most people hear “firm handshake” and robotically consider the business world. A cursory search reveals articles with titles like “Seven Revealing Things Your Handshake Says About You” (Forbes) and “How a handshake can tell you everything you need to know about a person” (Incl.).
But those that know know what your handshake Really reveals: your current health status, possible future diseases, and the way long you may live. In fact, grip strength often is the most revealing health metric your doctor has never measured.
During a typical doctor's visit, you expect your doctor to record your temperature, weight, heart rate and blood pressure. These measurements are called “vital signs” for a reason. They provide a fast snapshot of your current condition and supply clues about your future health.
However, there may be an excellent argument for including grip strength on this group. Grip strength testing is straightforward, quick and non-invasive, and could be monitored over time. All that’s required is a handgrip dynamometer, a tool that will cost lower than the stethoscope on the doctor's, and a chair.
What does grip strength reveal? The force you’ll be able to generate together with your hand is a sound indicator of overall body strength. And overall body strength is a key to healthy aging.
“In many studies, strength has been considered an indicator of positive health and weakness as an indicator of negative health consequences,” said Mark Peterson, PhDassociate professor of physical medicine and rehabilitation research on the University of Michigan who has participated in dozens of those studies.
Among the Health risks associated with poor grip strength:
- Type 2 diabetes
- Heart disease
- Cancer
- Dementia and Alzheimer's disease
- depression
- Functional disability
- osteoporosis
- Premature death from any cause
The predictive advantages of grip strength have been documented across continents and culturesAlthough most of those studies focused on older adults, they will not be the one age group that researchers have examined.
“We have several papers on the importance of grip strength in predicting diabetes and cardiovascular disease in children and adolescents,” Peterson said.
Why grip strength? How can the force generated by such small muscles within the hand and forearm be linked to so many vital consequences?
Survival of the fittest
The very first thing to know about grip strength testing is that it's only partly concerning the grip. It's mostly about strength. That's what drew Peterson to this area of research.
“I'm a former strength coach, so I wanted to explain why strength is important for all population groups, not just athletes,” he said. “I firmly believe that maintaining strength and a healthy lifestyle are a guarantee for a long life.”
Consider a classic study of Swedish army recruitsDue to Sweden's conscription policy after World War II, virtually every young man within the country underwent a physical examination to find out his fitness for military service – which included a test of grip strength.
This gave the researchers a database of greater than one million participants. Decades later, they followed them up using publicly available records.
What they found: The men with the weakest grip strength were 20% more prone to die of their late teens to mid-50s than those with medium to high grip strength. Even the suicide rate was 20 to 30% higher among the many weakest recruits.
There is a brutal Darwinian logic to the concept a stronger person with a stronger grip would enjoy an extended and healthier life. For our ancestors, stronger hands probably meant being higher at every part that was mandatory for survival: hunting, fighting, constructing shelters, and bearing and raising children.
Those with such a bonus could be more attractive to potential partners. They would then have more children, and people children could be stronger and healthier because of genetics and nutrition.
Fast forward to the twenty first century, where we now have to force ourselves to be physically lively, although science keeps showing us why it’s so necessary for health and longevity. The old rules still apply: strength helps you survive.
Grip strength and the aging process
Some of the primary grip strength studies used it as an indicator of nutritional status in older men and ladies. Diet, in turn, predicted their ability to survive illness or surgery.
And it is sensible: When an elderly person doesn't eat enough to remain healthy and vital, their strength declines. Declining strength makes them more vulnerable to infections, hospitalizations, and post-operative complications, resulting in longer hospital stays, lack of independence, and ultimately the next risk of death from any cause.
In this sense, Peterson’s research team on the University of Michigan found that Low grip strength correlates with faster aging on the cellular level.
The study examined DNA methylation, which Peterson describes as “a reflection of a person’s exposure to certain life events.”
For example, smokers have altered methylation patterns in comparison with non-smokers. The same applies to people who find themselves exposed to higher levels of environmental pollution.
Accelerated DNA methylation “means you're fundamentally at higher risk for what are traditionally considered age-related chronic diseases,” Peterson said. These diseases include Alzheimer's disease, type 2 diabetes, chronic inflammation and the next risk of premature death.
As you could recall, these aspects are also related to lower grip strength, which we now know is linked to higher DNA methylation and faster biological aging.
But there continues to be one piece of the puzzle missing: Why exactly is the strength of your grip linked to so many health consequences?
Grip strength and muscle function
“The loss of muscle function is the first step in the disability process,” said Ryan McGrath, PhDAssistant professor of health, nutrition and exercise sciences at North Dakota State University. “You can measure that with a handgrip test. That can help you identify people who are at risk for the next step in the process, which is a decline in physical performance.”
McGrath conducted grip strength research as a postdoctoral fellow on the University of Michigan, where he worked with Peterson. Like his mentor, he has published quite a few studies using data obtained with a handgrip dynamometer.
“It can be a good tool for assessing muscle function and strength,” he explained. Because the test is so easy to perform – you sit in a chair, rest your arm at your side, bend your elbow to 90 degrees and squeeze the device as hard as you’ll be able to – researchers can work with large groups and procure statistically meaningful data.
“There are numerous health consequences associated with it. That is one of its greatest strengths and one of its greatest weaknesses,” McGrath said.
He compared the dynamometer to a tire pressure gauge. Just as a tire pressure gauge can warn you to a lack of pressure without revealing the reason behind the leak, a dynamometer cannot let you know why your grip strength has decreased.
“It's hard to give a predictive value,” he said. “You don't know what steps to take next. As a standalone measure, it's concerning.”
That's why his current research goes beyond easy tests of maximum grip strength to incorporate more complex measures of rate of force development (how quickly you’ll be able to exert force), repeatability (how much your strength drops between the primary and second or third grip), and asymmetry (how big the difference is between the strength of your right and left hands).
Any of those measures could detect a possible neuronal or neuromuscular problem.
In a 2020 study, for instance, McGrath and his team at NDSU showed that older adults with weakness and asymmetry In grip strength tests, children were almost 4 times more prone to experience functional limitations. These limitations could affect their ability to do every part from routine tasks to private care and feeding.
This brings us to perhaps crucial query: What do you do with grip strength data from a patient, client or yourself once you’ve got it?
Waging war against weakness
Defining weakness is simple. Using dynamometer readings, the commonly accepted limits for weak grip strength are 26 kilograms for an adult male and 16 kilograms for a female. (As you will note in a moment, it is healthier to make use of kilograms fairly than kilos.)
But that's far too easy, Peterson said.
Firstly, your age plays a task. Grip strength typically reaches its peak for men of their late 20s and declines rapidly in middle age and beyond. For women, it reaches a plateau of their 20s and declines slowly until their 50s, so you need to at the least seek the advice of the age-based standards you include with a dynamometer.
One more caveat: Peterson said grip strength tests aren't very informative for individuals who actively engage in strength training, although he suggests that dedicated athletes make up a comparatively small percentage of the population – as little as 10%.
The height of the person being examined also plays a task.
“You absolutely have to consider body mass if you want to understand how grip strength or any other measure of strength affects health and function,” Peterson said.
To calculate your strength-to-weight ratio (which Peterson calls “normalized grip strength”), simply divide your grip strength in kilograms by your body weight in kilograms. For men, a ratio above 0.70 is in the highest percentile. For women, it's 0.50. (A full table of normalized grip strength percentiles could be found here.) Here.)
And what if the outcomes suggest that the person in query is objectively weak? “For me, it's simple,” Peterson said. “You have to exercise.”
Common sense suggests doing plenty of forearm exercises for grip strength. That's not the case, says Peterson. The strength of your hand and forearm muscles reflects what they’ll do along side the movement of all of your other muscles.
A 2019 study found that older adults a variety of training programs can result in modest but meaningful improvements in participants' grip strength – they usually don't necessarily need to involve actual gripping exercises. The programs ranged from Tai Chi to water aerobics to walking, stretching and all types of resistance training.
Peterson's advice to everyone seems to be pretty straightforward: Get stronger. It doesn't really matter the way you do it or how much strength you ultimately gain. Even a bit of more strength means a bit of less weakness and a bit of more life.