From sports to general health, most of us were raised on a version of fitness that treats cardio and strength as two different teams. Runners ran. Lifters lifted. And crossing over felt like betrayal—or at least a waste of the training time you’d already invested in your team.
But feelings and reality aren’t always on the same page.
A few days ago, Josh Kerr broke the mile world record that had stood since 1999. He ran 3:42.66 in London, finally getting under the 3:43.13 Hicham El Guerrouj had held for 27 years. Kerr didn’t get there by narrowing his focus down to running (like many of his peers)—he’s credited his twice-weekly strength training (mobility, kettlebell swings, barbell deadlifts, dumbbell bench presses, pullups, and core work) as the biggest factor in staying healthy enough to train at the volume a world record demands.
Of course, you don’t need to be chasing a world record to put that same idea to work. One of the things I’ve always enjoyed about kettlebells specifically is that they don’t make you “choose” between strength or cardio. Get-ups, squats, and presses build strength the way you’d expect from any reasonable weight. And swings, snatches, and jerks produce similar cardiovascular benefits to running or rowing—and double as strength work when you load them heavy and keep the reps low.
But the tool is beside the point. Whether it’s a track, rower, barbell, or kettlebell, the pattern holds: strength and cardio aren’t competing priorities—for a world record or a long life.
What each one predicts on its own
When it comes to longevity, both matter independently (before you even get to what happens when you combine them).
A 2025 analysis from the Copenhagen City Heart Study followed nearly 10,000 adults for 27 years and tracked who was still alive at the end of it. Findings showed that higher cardiorespiratory fitness (CRF) was associated with meaningfully lower all-cause and cardiovascular mortality. Higher muscle strength, measured by grip test, was protective too—a bit less strongly than CRF in this particular cohort, but far from negligible.
In any case, the real question isn’t which of the two is better if longevity is the goal—it’s what happens when you have both.
What happens when you combine them
A 2018 UK Biobank study followed close to 71,000 adults and directly compared four groups: low CRF and low grip strength, high CRF and low grip strength, low CRF and high grip strength, and high in both. People in the bottom fitness category for both measures were the reference point. The two mixed groups landed in between: high CRF paired with low grip strength cut all-cause mortality risk by 42%, low CRF paired with high grip strength by 29%—with CRF carrying more of the weight (though the two estimates overlapped enough that the gap isn’t a sure thing). More importantly, people with high CRF and high grip strength had a 47% lower risk of all-cause mortality—and a 69% lower risk of cardiovascular mortality—compared to the reference group.
That number comes from one study, though the direction it points—combined strength and cardio beating either alone—shows up consistently elsewhere. Either way, the practical takeaway doesn’t change: training both strength and cardio pays off more than picking one.
Putting it into practice
For those whose training has been mostly focused on a single modality (strength or cardio), adding the other doesn’t need to be complicated. If you’ve traditionally focused on cardio, one or two half-hour resistance training sessions per week is enough to move the needle. Alternatively, lifters will benefit from a cardio session or two (hike, ruck, swim, bike, sports like basketball or pickleball) of similar length. And if you’re short on time, swapping one of your current sessions for some kettlebell training is a perfectly viable option.
If you’re already doing some version of both, keep at it, of course. But also, the more useful next step might not be for you—it might be sharing this tip with someone who’s still choosing sides. Forward it, or just bring it up next time it’s relevant.
Whatever your situation, start small. The goal isn’t to completely develop a lagging capacity by next month. It’s to make sure neither one is neglected for the next fifty years.