On a Sunday morning, I dragged my hungover ass out of bed and clipped my index finger to a pulse oximeter—a thumb-sized monitor that measures heart rate. According to iHeart, the health and wellness app that syncs the device with an iPhone or iPad, I was now 38 years old.
That's just 15 years off. I'm 23.
After I spent 30 seconds nervously staring at the pulse signals on my phone screen, iHeart determined my "internal age," which is a term its designers use to describe the suppleness of the body's interior at a particular point in time. In other words, the app calculated the extent to which my evening of Smirnoff shots and lack of sleep had, at least temporarily, impacted my body's insides. The device determines this measurement, they say, by using the pulse signal found in the index fingertip to measure the flexibility of the aorta, the large artery that extends from the heart to the abdomen.
"With stiffening of the aorta, there's an increased risk of death from all causes," the app's inventor, a Toronto medical doctor named Jess Goodman, told me. Goodman emphasized that through exercise, attention to diet, and reduction in stress, aortic stiffness can improve.
iHeart was originally intended to help middle-agers monitor physiological well-being. But in March, a report from the Framingham Heart Study gave reason to think that younger people could benefit, too. The study suggested that aortic stiffness could indicate troublesome brain changes as early as young adulthood—much sooner than what researchers previously suspected.
Curious to see how my own habits might be impacting my internal age, I spent the weekend attached to the app's pulse oximeter. And though I didn't really need the $200 device to remind me that a sleepless night of abusing alcohol might not be health-conscious—I have my mother for that—I'll admit that getting wasted at the bar is far less appealing when an app tells you that your physiological age is approaching 40.
I was taken aback by how suddenly—and drastically—my internal age could vary. When I stress-ate half a pack of quinoa chips, I turned 33. When my Uber driver reeked of weed and body odour, I was 38 again. When I sweat out my Sunday morning toxins in a yoga class, I was back in my 20s. After a relaxing nap, my internal age reached an all-time low of 25.
"You can see how changing a tiny aspect of your lifestyle makes a difference," Sarah Goodman, Jess's daughter and iHeart CEO, told me. "It's a snapshot of how you're doing at that moment."
A mere weekend with the device was an inadequate amount of time to monitor any real changes in my aortic stiffness, Jess told me. He said that if I used the app on a regular basis, I would begin to notice patterns in my pulse analysis results. He encourages users to test themselves at the same time every day, after they have been resting for at least two minutes.
Ideally, internal age should range within 5 to 10 years of one's biological age, Jess said.
Not all doctors are sold on the usefulness of this sort of device. David Mazer, a cardiac anaesthesiologist at St. Michael's Hospital in Toronto (who had no prior knowledge of iHeart), agreed that measuring pulse wave velocity does indicate aortic stiffness, and that doctors are always looking for new ways to promote cardiovascular health. But, like me, he questioned whether such rapid changes in "internal age" are a meaningful sign of health.
"[Users] could become obsessed with the app," Mazer said. "They might repeatedly measure the number, or misinterpret what it says." Jess stressed that iHeart is a health and wellness app, not a medical device, and that it's only meant to direct its users to adopt healthier habits.
I decided to perform a little experiment, and see how my "internal age" stacked up against my father's. Compared to him, I'm pretty much a health nut. I work out almost daily, adhere to a fairly healthy diet, rarely smoke, and drink only on the weekends. But apparently, as we relaxed over lunch, my dad was, at least temporarily, in better shape.
I asked him to try out the device. An overweight 64-year-old with a fondness for Camel cigarettes and a nightly glass of vodka on the rocks, he'd just taken his blood pressure medication, which stacked the odds in his favour. And I'd just chugged a cup of coffee, which can temporarily raise a person's blood pressure, so that was probably working against me.
My father, the real-life Benjamin Button, gloated at his internal age of 39. Meanwhile, I had reached my highest age of the weekend: 43.