A drop of 15% in muscle strength can already serve as a warning sign of future mobility loss in older adults, even when their strength still falls within normal ranges, according to a study by researchers at the Federal University of São Carlos (UFSCar) in Brazil and University College London in the United Kingdom.
The study tracked 4,541 people aged 60 or older over 12 years and found that monitoring how a person's strength changes over time can help identify, at an early stage, the risk of slower walking speed later in life. Grip strength, measured by hand squeeze, was one of the parameters used.
A decline in walking speed is considered another key indicator of health in old age, since it is linked to a higher risk of falls, hospitalization and loss of independence.
The findings were published in the scientific journal GeroScience and were supported by the São Paulo Research Foundation (FAPESP), a Brazilian public agency that funds scientific research.
Grip strength as a health gauge
To track muscle strength, the researchers used handgrip strength, a simple test that serves as an indicator of the body's overall muscular condition.
One of the parameters currently used to identify weakness in older adults sets the threshold below 27 kilograms of force for men and 16 kilograms for women.
The new study showed that a person does not necessarily need to fall below those thresholds to show a warning sign. Tiago da Silva Alexandre, a professor in UFSCar's Department of Gerontology and the study's coordinator, said that even individuals who remained above the minimum threshold entered a process leading to slower walking after losing 15% of their strength.
Why losing strength affects walking
Muscle strength is necessary for basic daily movements, such as standing up, rising from a chair and walking.
Alexandre explained that muscle strength is one of the pillars of mobility. He said that although balance, absence of pain, flexibility and cardiorespiratory capacity also play a role, without a minimum reserve of strength the body cannot sustain basic movements such as standing up, walking or maintaining stability while standing.
Among the older adults who lost between 15% and 20% of their strength over the 12 years, the cumulative reduction in walking speed reached 0.189 meters per second.
By comparison, walking speeds below 0.8 meters per second are already considered a sign of slowness and represent a warning for the health of older adults.
A possible clinical cutoff
According to the authors, the finding underscores the importance of tracking not just absolute strength values but how they change over time. A loss of more than 15% could serve as a clinical cutoff point to identify, early on, older adults at risk of declining mobility.
