A friend of mine used to tell me: “When we get to be 70 our bodies age twice as fast as they used to…” I’ve always wondered if this French popular expression held a kernel of truth and if it was the case was the multiplier “two” correct at 70, but how much should it be upgraded at 75, 80, 85, 90 and further as we age.
I wondered if there had been any studies made, what was objectively measured and what were the findings if any. After doing some research, I soon realized that my friend’s saying contained some figments of truth, but not in the literal sense that "the body suddenly ages twice as fast at 70." Researchers who study aging have found that aging is not linear.
Many aspects of human physiology decline gradually for decades and then accelerate at certain milestones. However, the acceleration differs depending on what’s being measured. There are in fact at least four ways to measure aging:- Mortality risk (chance of dying within a given year)
- Physical performance (strength, balance, walking speed, endurance)
- Organ function (heart, lungs, kidneys, immune system, etc.)
- Biological markers (DNA, proteins, inflammation, cellular changes)
The above categories or aspects do not all age simultaneously.
Starting with mortality risk, one of the most robust findings in demography is the Gompertz law, discovered in the 1820s. It shows that after adulthood, the risk of death increases approximately exponentially with age. A rough rule is that mortality risk doubles every 7–9 years after middle age.
For example, if a healthy 60-year-old has a certain annual risk of death, at 68–69, that risk is about twice as high. At 76–78, it’s about four times as high, then at 84–87, it’s about eight times as high. This does not mean the body is aging twice as fast; it means the consequences of accumulated aging become increasingly apparent.
In terms of physical capabilities, we see several bodily functions declining at an accelerated rate, starting with muscle mass and strength. After age 30, muscle mass declines slowly (about 3–8% per decade), but past age 60–70 the loss often accelerates significantly, with strength falling faster than muscle mass itself.
This is why many people notice that, at 80, they may lose strength in a year that would have taken several years to lose at 50. Walking speed and balance both decline gradually until about 70, then the slope steepens after 75–80. These measures are among the best predictors of future health and longevity.Tomorrow, we’ll talk about how aging affects organ functions and other biological markers...





