On the journey from hale to frail, which physical attribute is the first to fade and rob you of independence?

A new study examined three markers of physical ability to see which of them declined at the fastest rate and was the most reliable measure of ageing.

These were:

• The loss of muscle mass and strength is a dire consequence of ageing and doing no exercise. By slowing muscle loss and maintaining strength through exercise, we protect the joints as they degenerate and we’re less likely to suffer a fall
• The loss of an efficient gait, or walking style. Gait velocity slows because older adults take shorter steps at the same rate
• The ability to balance on one leg.

These are all connected. For example, the most likely reason for shortened step length is weakness of the calf muscles, which propel the body forward. Calf muscle strength is substantially decreased in older adults. And when the gait becomes unsteady, your balance is compromised.

The new study

But, in the Mayo Clinic study, it was found that the ability and length of time a person can stand on one leg “is a more telltale measure of ageing than changes in strength or gait”.

That is, you lose this ability at a faster rate than losing leg or grip strength, or shortening your stride.

In the study, 40 healthy, independent people over 50 underwent walking, balance, grip strength and knee strength tests. Half of the participants were under 65; the other half were 65 and older.

In the balance tests, the participants were instructed to hold a variety of poses while standing on a force plate. A force plate is a boxy-looking platform containing a number of sensors. They measure the posture, power, and positions of athletes and patients as they move.

In the study, participants stood:

• On both feet with eyes open
• On both feet with eyes closed
• On the non-dominant leg with eyes open
• On the dominant leg with eyes open.

In the one-legged tests, participants could hold the leg they weren’t standing on where they wanted. The tests were 30 seconds each.

Standing on one leg – specifically the non-dominant leg – showed the highest rate of decline with age.

In other findings: There were no age-related declines in the strength tests that were specific to sex. This indicates that participants’ grip and knee strength declined at a similar rate.

Researchers did not identify sex differences in the gait and balance tests, which suggests that male and female subjects were equally affected by age.

What the researcher says

Dr Kenton Kaufman, senior author of the study and director of the Motion Analysis Laboratory at Mayo Clinic, said:

“Balance is an important measure because, in addition to muscle strength, it requires input from vision, the vestibular system and the somatosensory systems.”

The vestibular system functions to detect the position and movement of our head in space. This allows for the co-ordination of eye movements, posture, and equilibrium.

The somatosensory system is, in part, concerned with the conscious perception of touch, pressure, pain, temperature, position and movement.

“Changes in balance are noteworthy,” said Kaufman.

“If you have poor balance, you’re at risk of falling, whether or not you’re moving. Falls are a severe health risk with serious consequences.”

Kaufman said people can take steps to train their balance. For example, by standing on one leg, you can train yourself to co-ordinate your muscle and vestibular responses to maintain correct balance.

If you can stand on one leg for 30 seconds, you are doing well, he said.

 A 2022 international study, which included researchers from the University of Sydney, found that “the inability to stand on one leg for 10 seconds in mid-to-later life is linked to a near doubling in the risk of death from any cause within the next 10 years”.