Does Strength Training Actually Slow Aging?

Yes. And the data is specific about how much.

The UK Biobank tracked over 70,000 adults. The ones in the top tier for both cardio fitness and grip strength had 47% lower all-cause mortality than the bottom tier. Not either one. Both.

That is the part people skip. You can be a strong person who gets winded on stairs. You can be a runner who cannot open a jar in twenty years. Neither of those people showed up in the top tier. The people who did were training both at once.

This is not a supplement stack or a morning routine. It is two things, done consistently, in the same week: heavy resistance work and real aerobic effort. The study did not reward intensity. It rewarded the combination.

Most programs pick a lane. Lifters lift. Runners run. The body does not care which one you are loyal to. It cares whether both systems are getting pushed.

If you have spent years doing one and skipping the other, this is the number that should bother you. Not because you are behind. Because the fix is boring and already known. Lift heavy. Get your heart rate up. Do both in the same week, every week, and keep doing it as the decades stack.

Source: Kim Y, et al. Eur J Epidemiol. 2018. UK Biobank cohort, 70,913 adults.