Functional Testing Can Happen at Home

In Part 1 I argued that movement is a vital sign we don't measure. The obvious next question is where you'd measure it, and my answer is not the clinic.

Why the clinic is the wrong place to start

A functional test at a clinic visit gives you one number. It's taken in a room the patient doesn't know, usually once or twice a year. That tells you how someone moved that day. It doesn't tell you if they're getting stronger, slowing down, or getting close to a fall. To see a trend you need a lot of readings, and the only place you get a lot of readings is at home.

What the research shows so far

The simple tests most clinicians already know, like the chair stand, five sit-to-stands and Timed Up and Go, seem to hold up when the patient does them at home. In one study, older adults did the tests in their own homes while one rater watched in person and another watched by video, and the two scored them almost the same (study). Another study had fourteen older adults do the tests on their own and repeat them four weeks later, and the results were very consistent (study). Those are small groups of people who were willing to take part, so I wouldn't stretch the conclusion. I do take from it that a chair and a phone can produce real data.

Phones can do more than time a stopwatch. A 2023 study in npj Digital Medicine had 405 people across 35 states film themselves doing five sit-to-stands at home. What the researchers pulled from the videos lined up with osteoarthritis diagnoses and with how people rated their own physical and mental health (study). The home times also ran longer than the reference numbers the authors compared against, about 11.4 seconds versus 7.5. Home numbers aren't clinic numbers, so a program needs its own ranges and a consistent setup.

Then there's the data from wearing a sensor through a normal week. In a 2023 study in the Journals of Gerontology, the usual clinic mobility tests didn't predict who fell. Walking cadence measured by a wearable in daily life did, at least for people who were already doing well. Every 10 extra steps a minute went with a 27.7% lower fall rate (study). It's early, but it suggests a lot of what matters happens outside the visit.

What has to be sorted out first

Moving testing home creates work. People need instructions they can follow alone, including chair height, how much floor space to clear, and where to put the camera. Someone has to decide who is safe to test without another person nearby. Someone has to look at the results and tell a good test from a bad one. And the results have to end up in the record where the clinician already works, because a separate portal won't get opened.

Next

Collecting data at home is the first step. The second is knowing the number actually means something. Part 3 is about what makes a movement measure a real biomarker.

Disclosure: I'm VP of Operations at BioMech Health, which works in objective movement measurement. This series reflects my own views and isn't about any specific product.