The final decades of a human's life are a litany of gradual mechanical failures. Strength wanes, fitness drops, and the brain can get a little foggy.
Balance is among the first to slide, sending us wobbling some time in our mid-fifties. Given the fact that falls are a major cause of injury-based death around the world, keeping track of this vital function should be more of a priority than it currently is.
One obstacle to medical surveillance of balance in old age is we simply don't know what to look for as an early sign of decline. So, an international team of researchers in sports medicine crunched the clinical data collected as part of a large ongoing study on exercise.
Subjects were aged from their fifties to early seventies when their first evaluation took place. As part of their assessment, they were required to stand on their left or right leg for 10 seconds, with their raised foot tucked behind their standing leg, keeping their arms by their sides.
"The one-legged stance test has been used to assess balance over the last five decades, but it is not routinely employed in the clinical examination of middle-aged and older individuals," says medical scientist Setor Kunutsor from the Bristol Medical School in the UK.
To make it as fair as possible, each participant could make three attempts.
It's a relatively simple task with a clear outcome. Either they could make it to the end of the count in at least one of their tests, or they began to tip.
Of the 1,702 volunteers who took part between 2009 and late 2020, nearly 350 - that's 1 in 5 - couldn't hold their balance, a result that became twice as likely for every additional 5 years of aging.
The participants' health was subsequently tracked over the years, detailing deaths and their likely causes. Sure enough, more participants who had been unable to hold their balance died within the study period.
In fact, only 4.5 percent of those who could successfully stand on one leg for a whole 10 seconds passed away, compared with more than 17 percent of those who couldn't.
The cause of deaths in each group didn't vary a great deal, including diseases such as cancer, cardiovascular disease, and even a handful from COVID.
That said, those who struggled to keep their balance were, in general, less healthy, with more cases of coronary artery disease, hypertension, and diabetes, potentially contributing to ailing health and reduced capacity for recovery.
Taking everything from age to sex to underlying conditions into account, being unable to stand on one leg without support for a whole 10 seconds made volunteers 84 percent more likely to die within the following 10 years.
Exactly why this is the case isn't clear. That's the weird thing with observational studies like these - researchers can only compare factors, such as death and balance, and calculate comparisons in the odds.
It's possible a variety of subtle influences are at work. Some could be indirect, where illness affecting the apparatus we use to stay steady on our feet also decreases general health in other ways.
Falling is a major cause of death worldwide, with around 684,000 individuals succumbing to injuries that result from a serious topple. It's likely a proportion of these - especially among the elderly - could have been avoided, or at least mitigated, by adequate balance.
Having a tool for balance that is based on a quantitative measure of risk is a great starting place for assessing who might benefit from intervening exercises, or simply need to take greater care.
It's important to add that the results were based on people who were primarily white and from a more affluent background, relatively speaking. It's also possible there were other factors hidden to the researchers, such as medications that could affect balance or a history of falls.
Studies like these aren't always going to give us the whole story straight away. But the evidence so far is enough to show how monitoring our balance could benefit us in our later years.
"The current findings suggest the 10-second one-legged stance is a potential practical tool that could be used in routine clinical practice to identify middle-aged and older individuals at high risk of death," says Kunutsor.
This research was published in the British Journal of Sports Medicine.