News · Fitness & Exercise
A 10% gap between the hands went with higher odds of stacked heart and diabetes conditions
Grip strength is a standard measure of aging, usually read as a single number. Comparing the two hands against each other picked out risk that overall weakness did not.
- An observational study of 8,132 Chinese adults aged 45 to 80, followed for up to nine years.
- Asymmetry meant one hand testing at least 10% stronger than the other.
- 848 people developed two or more of diabetes, heart disease and stroke during follow-up.
- Uneven grip alone carried higher odds; uneven and weak together carried the highest.
- Being weak without being uneven showed no clear signal, which is the surprise.
Grip strength has become one of the standard measures of how well someone is aging, because it is cheap, quick and correlates with almost everything: mortality, fracture, recovery after surgery, cognitive decline. It is nearly always reported as a single number, the best of a few squeezes.
A study in Experimental Gerontology, following 8,132 middle-aged and older Chinese adults, asked a different question: not how strong the grip is, but how similar the two hands are. The gap between the hands turned out to carry a signal that overall weakness did not.
What grip strength is used for
The test is deliberately simple. Squeeze a handheld gauge as hard as you can, record the best effort, compare against reference values for age and sex. Low grip strength is one of the defining criteria for sarcopenia, the age-related loss of muscle.
Its value comes from being a proxy for something broader. Grip reflects muscle mass, nerve function, nutrition and the general reserve a body holds, which is why it predicts outcomes far removed from hands. MedlinePlus makes the general case plainly: regular exercise is one of the best things you can do for your health, with benefits including reducing your risk for many chronic diseases.
How the two hands were compared
The definition is the part to hold on to. Handgrip asymmetry was defined as a 10% or greater relative difference between hands, which is more than the ordinary gap between a dominant and non-dominant hand. Low strength was defined separately, against the Asian Working Group for Sarcopenia criteria.
Crossing those two gave four groups: even and normal strength, uneven only, weak only, and both uneven and weak. Everyone came from the China Health and Retirement Longitudinal Study and was free of the outcome at the start, and follow-up ran from 2011 to 2020.
The outcome was the stacking of conditions: cardiometabolic multimorbidity, defined as at least two conditions among diabetes, heart disease, and stroke. During follow-up, 848 participants, about one in ten, developed it.
What the gap between hands predicted
Unevenness on its own mattered. Compared with people who were even and normal in strength, those who were asymmetric only carried a 23% higher risk of developing two or more of those conditions.
The combination was worse. Being both asymmetric and weak was associated with a 67% higher risk, which is the group any clinician would expect to do badly.
The surprise is the fourth group. Being weak without being uneven was not significantly associated with the outcome, despite low grip strength being the measure everyone actually uses.
Why a grip gap might beat weakness as a signal
Nobody knows, and the paper does not claim to. The most plausible account is that the two measures capture different things.
General weakness is a whole-body phenomenon: less muscle, less activity, less food, more age. It is common, and it accumulates slowly in everybody, which may be precisely why it fails to separate one person’s risk from another’s in a population this age.
A sizeable gap between the two sides is different. It suggests something asymmetric, and the body’s asymmetric problems tend to be neurological or vascular: a small stroke, a nerve compression, a circulation problem affecting one arm. If that is what asymmetry is detecting, it is picking up early damage rather than general decline, which would explain why it predicts a cluster of vascular and metabolic conditions.
That is a hypothesis built on a pattern, not a finding, and it is the obvious next thing to test.
What 8,132 grip measurements cannot show
Grip was measured at the start, so the study cannot tell whether an asymmetry that appears later carries the same meaning, or whether it changes over time.
Reverse causation has room here too. Undiagnosed vascular disease at baseline could produce both the asymmetry and the later diagnoses, in which case the grip test is detecting a condition that was already present rather than predicting a new one.
The cohort is also Chinese and middle-aged or older, with strength thresholds set by Asian criteria that differ from those used elsewhere. And the difference between hands is affected by ordinary things, including past injury, occupation and how strongly handed someone is.
What to take from the grip asymmetry finding
Nothing to do at home, which is worth saying because grip dynamometers are sold to consumers and this is not a reason to buy one. There is no treatment for an uneven grip and no threshold that means anything for an individual.
Where it may matter is in research and in clinics that already measure grip, often in older patients being assessed for frailty. If asymmetry carries information that the single number misses, then recording both hands costs nothing and may flag people worth looking at more closely. The measurement is already being taken. Half of it is currently being thrown away.
People also ask
What did the study find?
During follow-up, 848 participants (10.4%) developed cardiometabolic multimorbidity, defined as at least two of diabetes, heart disease and stroke. In the fully adjusted model, asymmetry alone was associated with a 23% higher risk than being symmetric with normal strength (HR 1.23, 95% CI 1.06-1.42), and being both asymmetric and weak with a 67% higher risk (HR 1.67, 95% CI 1.27-2.20). Being weak alone was not significantly associated (HR 1.09, 95% CI 0.76-1.56).
How is grip asymmetry measured?
With a handheld dynamometer, squeezing as hard as possible with each hand in turn. Asymmetry here means the stronger hand exceeded the weaker by at least 10%, which is a larger gap than the usual difference between a dominant and non-dominant hand.
What is cardiometabolic multimorbidity?
Having more than one of diabetes, heart disease and stroke at the same time. It is tracked separately from any single condition because the combination is harder to treat and carries worse outcomes than the sum of its parts.
Why would unevenness matter more than weakness?
The study cannot say. One suggestion is that asymmetry reflects something neurological or vascular affecting one side rather than general muscle loss, so it may be picking up a different problem rather than a worse version of the same one.
Should I test my grip at home?
There is no need. This is a research measure used to compare groups, the difference between hands varies for ordinary reasons including injury and handedness, and no treatment follows from the number.
What actually reduces this risk?
The things that reduce each condition separately: activity, not smoking, blood pressure and blood sugar control. This is general information rather than medical advice.