Why do some people get much fitter from the same training while others barely budge?
Researchers followed older adults (aged 70–77) who did the Norwegian 4x4 interval workout twice a week for a full year.
Changes in peak VO2 ranged from a 56% increase to a 28% decline. They then compared 10 high responders (+22% on average) with 10 low responders, matched for age, sex, lean mass, and starting fitness.
A single hard workout shifted hundreds of blood proteins in both groups. But after a year, high responders had 394 resting proteins changed. Low responders had ZERO. The protein that best predicted who would improve was IGFBP7, which is released by senescent "zombie" cells. Higher levels before training meant smaller gains.
Mice without it gained 3.3 times more fitness on treadmill training, and raising it erased that advantage.
I'm still skeptical of true "non-responders.”Other research shows most of them improve once they train more. Interesting study, though!
Researchers followed older adults (aged 70–77) who did the Norwegian 4x4 interval workout twice a week for a full year.
Changes in peak VO2 ranged from a 56% increase to a 28% decline. They then compared 10 high responders (+22% on average) with 10 low responders, matched for age, sex, lean mass, and starting fitness.
A single hard workout shifted hundreds of blood proteins in both groups. But after a year, high responders had 394 resting proteins changed. Low responders had ZERO. The protein that best predicted who would improve was IGFBP7, which is released by senescent "zombie" cells. Higher levels before training meant smaller gains.
Mice without it gained 3.3 times more fitness on treadmill training, and raising it erased that advantage.
I'm still skeptical of true "non-responders.”Other research shows most of them improve once they train more. Interesting study, though!
