The answer lives in this podcast
The Diary Of A CEO with Steven Bartlett · Steven Bartlett
Why are strong legs particularly important for Alzheimer's prevention?
A study on identical twins — sharing the exact same genetic profile — tracked over a 10-year period with cognitive tests and MRIs found a striking result: the twin with the greatest strength and most leg power had a bigger brain, larger gray matter volume, better-preserved cognitive functions, and consistently outperformed the other on cognitive tests. Because twins eliminate genetic variables entirely, the difference in brain health was attributable directly to physical conditioning, making leg strength one of the clearest causal signals researchers have found in Alzheimer's prevention.
What is gray matter?
Your brain consists of both gray and white matter. Gray matter contains the cell bodies and lives on the outer portions of the brain. White matter, found deeper within the brain, is where myelinated neurons reside. Preserving gray matter volume is directly linked to maintaining cognitive function as we age — and the twin study measured exactly this.
This finding doesn't stand alone. The SMART trial reinforced the same conclusion from a different angle: people with mild cognitive impairment who completed resistance training two to three times per week not only preserved their cognitive functions — they enhanced their processing speed, improved their fluid intelligence, and slowed the loss of gray matter. Resistance training, specifically, delivers the greatest return on investment when it comes to brain protection. You can explore the full episode and more on this topic directly on Listenly.
"Having strong legs is by far the most important tool in your toolbox for the prevention of Alzheimer's disease."
— Episode: Alzheimer's Starts 20 Years Before Symptoms! How To Protect Your Brain Now · The Diary Of A CEO with Steven BartlettSee also
The ApoE4 gene (Apolipoprotein E gene) is one of the strongest genetic risk factors for Alzheimer's disease. One copy raises risk by two to three times for males and six-fold for females; two copies raise it ten times for males and fifteen-fold for females — though carrying the gene is not a foregone conclusion of developing the disease.
The SMART trial took a group of people with mild cognitive impairment and gave them resistance training two to three times per week. They not only preserved their cognitive functions but also enhanced their processing speed, improved their fluid intelligence, and experienced a measurable slowing of gray matter loss.