Here's a number worth sitting with: in a two-year clinical trial, previously sedentary people in their early 50s trained their hearts back to the elasticity of someone in their early 30s.
Not with a drug. Not with anything exotic. With about five hours of exercise a week, structured a particular way.
That trial has been doing the rounds again this month, and most of the coverage skips the details that actually matter. So let's go to the source.
The study
Researchers at UT Southwestern, led by Dr Benjamin Levine, recruited 61 healthy but sedentary adults (average age 53) who'd spent most of their adult lives not exercising. That matters, because the heart stiffens with disuse. A stiff left ventricle fills poorly, and that stiffening is one of the main roads to heart failure later in life.
Half the group was randomised into two years of progressive training. The other half did yoga, balance and light strength work as a control.
The results, published in Circulation (Howden et al., 2018): the training group improved their VO2max, the single best predictor of cardiovascular longevity we have, by 18%. More impressively, the stiffness of their left ventricle dropped significantly, with their heart mechanics ending up closer to those of healthy 30-somethings. The control group improved on none of it.
Twenty-plus years of sitting, meaningfully unwound in two.
What they actually did
This is the part most articles bury. The protocol built up to four to five sessions a week, roughly five hours all up:
- One interval session a week, the Norwegian 4x4: four rounds of 4 minutes hard (about 95% of max heart rate, a pace where you can't hold a conversation), each followed by 3 minutes easy. With warm-up and cool-down it's about 40 minutes.
- One longer session (an hour or so) at a comfortable, steady pace. A hilly walk, a ride, a swim.
- Two or three moderate 30-minute sessions, the kind where you can talk but you'd rather not sing.
- Strength training once or twice a week on top.
They didn't start there. Sessions were built up gradually over months, which is exactly how you should treat it too if you're currently doing very little.
The honest caveats
Fifty-three people finished the trial, so it's not a huge study. Everyone in it was healthy to begin with, and they were coached and monitored for the full two years.
Timing matters as well. Levine's team has found that hearts in the 70s are far less remodelable, and his line on it is blunt: the sweet spot is late middle age, when the heart still has plasticity. If you're in your 40s, 50s or early 60s and mostly sedentary, this study is speaking directly to you.
And no, you don't get the result in a fortnight. The stiffness changes showed up over the second year. This is a compounding investment, not a quick fix.
What to do with this
You don't need the lab. You need the dose. Start where you are:
Currently doing nothing? Walk 30 minutes, four days this week. That's the on-ramp the trial itself used.
Already moving a bit? Add one 4x4 interval session a week. Bike, hill walks, rower, whatever lets you get properly puffed for 4 minutes safely. If you have a heart condition or you're on medication, run it past your doctor first, no shortcuts on that one.
Then protect the streak. Five hours a week sounds like a lot until you see it laid out: it's about 45 minutes a day, and one rest day.
Your heart isn't stuck with the age on your licence. It responds to what you give it, decade after decade. Training is the biggest lever, and giving your heart the right raw materials day to day is ours. That's the whole reason StrongHeart exists.
Source: Howden EJ, Sarma S, Lawley JS, et al. Reversing the Cardiac Effects of Sedentary Aging in Middle Age — A Randomized Controlled Trial. Circulation, 2018.
This article is general information, not medical advice. Speak with your GP before starting a new exercise program, especially if you have an existing heart condition.