SerpApi.Org
If you’re a fitness-minded individual in their 20s or 30s reading this, you have probably encountered the resident older gentleman in your gym watching you work out saying “I used to be able to do that stuff.”
As the saying goes, Father Time is undefeated. While we have accepted this, the real question is why. Does aging itself impact your ability to build muscle and perform, or is it the slow deterioration in activity level that is responsible for the decline?
A unique new study looked at the muscle biopsies of four groups: young adults, older adults matched to young adults' activity levels, older adults who'd done real structured training (3x/week, an hour each, for over a year), and older adults with early frailty. They biopsied muscle and measured thousands of genes, metabolites, and fat molecules.
Aging muscle does in fact have an energy bottleneck. Over 1,000 genes involved in building the cell's energy-producing machinery (mitochondria) decline with age. NAD+ in particular drops with age. This is a molecule essential for creating energy from fuel. It is part of the reason why NAD+ supplements and peptides are becoming so popular. While it is not the entire story of energy production, it does play an important role.
In conjunction with the drop in NAD+, fat begins to accumulate in muscle. This is not visceral or subcutaneous fat; this is inside the muscle itself in the form of intramuscular triglycerides. This causes a downstream effect which can potentially lead to insulin resistance.
Structured training prevented over half of this decline. Roughly 55–57% of the age-related gene changes simply weren't present in the trained older adults. Their muscle looked biologically younger. Walking wasn’t enough to avoid these changes though; it has to be meaningful endurance training (it’s unclear the effect resistance training would have as this study did not look at it).
Changes related to nerve-muscle communication and a tissue-maintenance pathway (WNT signaling) showed up in all older adults regardless of training. So there are certain things that cannot be reversed through physical activity alone.
This study shows that, while you can’t change everything, you can maintain quite a bit of your youth with structured training. It’s important to note that this study was not an intervention; it was more a snapshot in time using various groups of people. It’s unclear if adding exercise for an inactive adult would reverse these changes, so it’s best to get ahead of the game.
With that said, roughly half of what we chalk up to “getting old” is actually preventable, and the mechanism looks concrete: preserved mitochondria, preserved NAD+, and muscle that keeps generating energy the way younger muscle does.
