It’s a numbers thing. The most common marker of mortality is the body mass index, which is your weight to height ratio. But BMI is often bullshit. It’ll label Kahlil Mack obese and say some skinny dude with a beer belly and Twinkie diet is the epitome of health, without ever factoring in muscle and fat. And, as for your vital signs—blood pressure, breathing rate, pulse, and temperature—they’re like dashboard warning lights: invaluable when something is going wrong but otherwise not so much. Out with the old, in with the new. Recently, researchers have discovered numbers that better demonstrate health and predict mortality, and they have a lot more to do with the gym than the doctor’s office.

THE NEW VITAL SIGNS

WALKING SPEED

One of those numbers is 2.6, as in feet per second. An analysis of nearly 35,000 seniors found that those who walked at about 2.6 feet per second over a short distance (a rate of slightly less than 2 m.p.h.) were likely to hit their average life expectancy, and for every four inches farther they perambulated per second their chance of dying in the next decade dropped by about 12%.

GRIP STRENGTH

A hand dynamometer tests grip strength / U.S. Air Force photo by Staff Sgt. Damien Taylor

A 2018 study of over a half-million (!) people, aged 40-69, found that heart disease, respiratory disease, most cancers, and all-cause mortality were higher amongst those with lower grip strength. Grip was a better predictor of mortality than blood pressure.

And if you think that’s just a middle-aged thing, the Swedish military tested over 1.1 million (!!) males, aged 16-19, for grip and leg strength and followed up 24 years later. Those who demonstrated “high muscular strength” as teenagers had a 20-35% lower risk of premature mortality, independent of BMI or blood pressure. Those in the lowest 10% for strength “showed by far the highest risk of mortality for different causes.”

PUSHUPS

In a 10-year Harvard study of 1104 firefighters, aged 21-66, there was a strong correlation between pushup capacity and heart disease. Participants able to do more than 40 pushups were 96% less likely to have a cardiovascular disease event than those who completed fewer than 10. Pushups were more strongly associated with cardiovascular disease risk than treadmill tests.

photo: Mike Baird

GET STRONGER, LIVE LONGER

Walking pace, gripping, and pushups are merely gauges of general fitness. They have the advantage of simplicity, and their tests can be performed quickly for little or no cost almost anywhere.

Take the pushup. It’s a strength indicator—both upper body and core, if performed strictly—and, at higher reps, a cardiovascular indicator, that can override the BMI. A smoker with an ideal BMI who’s never entered a gym is likely to struggle to get 10, but someone with The Rock’s physique and an “obese” BMI might go all day. And a blob will never get his belly off the floor. The simple pushup helps to reveal what the BMI misses: How much of the body mass is muscle and how much is fat?

What’s more, becoming more proficient in pushups, or stronger and more fit in general (even just walking faster at 80), requires a conscious commitment, and that, in and of itself, is an indication that you’re focused on the sort of self-improvement that, on average, leads to a longer life. You’re probably less likely to indulge in unhealthy activities and more likely to develop healthy habits in diet, exercise, and recovery. Get stronger, live longer. Now drop and give us 50.

(Painting: The Death of Socrates, Jacques-Louis David, 1787)