A question about genetic limits or potential

Hello doctors, I had a simple question, not sure if this should go in training Q/A or some other section, but I ended up settling for this.

As far as I am aware, it is generally accepted that every person when it comes to strength training and such has their own “genetic potential” or “limit” that will dictate how far they can go with this endeavor assuming everything else such as training variables, motivation and environment are dialed in. Not everyone who is 220lbs is capable of deadlifting 750lbs for example due to genetic factors.

All of that is well accepted from what I know, but I’ve recently seen some people online, both just random commenters or prolific influencers expressing the idea that there is no “genetic limit” or “natural/natty limit” as some like to say and that you should expect to keep making slower and slower progress until you reach a certain age. In other words, these guys are saying that the actual “genetic limit” for muscle mass or strength doesn’t exist, but what limits you is age, basically suggesting you eventually “run out of time” to make any more gains and then regress, but you would never hit a limit when you are younger. So basically suggesting if you theoretically remained 25 forever and were immortal you should expect “endless gains” without any peds.

My question is that is there actually any evidence to support this line of thinking or do these people just simply not know what they are talking about like most people online? I’ve just always assumed that your genetic potential for muscle mass and strength was independent of age and that even if you could theoretically remain “young” forever, with enough years of training you would still hit a genetic ceiling nonetheless, since I’ve known people who’ve been training since they were teenagers and with about two decades of training, by the time they are in their late 30’s or so which is still young, they tend to max out their potential regardless.

In case it matters, the people who promote this idea also tend to care about “hormone levels” or “testosterone” a lot and tend to say that gains stop with age “due to decline in testosterone levels” and that if “your testosterone levels remain as high as when you are 20, you shouldn’t stop gaining” whereas I’ve heard you guys’s content suggest t levels within the normal range are irrelevant for strength or hypertrophy outcomes.

Someone making a claim without evidence can be dismissed without evidence. Easy peasy. A few additional thoughts:

  1. We have pretty good evidence that people respond differently to the same exercise plan, independent of T levels, sex, age, etc. This means that there are other things responsible for how someone responds to training than their hormones, sex, ethnicity, and so on. Genes play a big role.
  2. Depending on the specific quality being assessed, somewhere between 30-80% of a person’s strength, power, and muscle mass levels are attributed to genetic differences (Genetic inheritance effects on endurance and muscle strength: an update - PubMed)
  3. Long-term data on strength athletes, where strength performance in sport is the most important thing in their lives shows that the peak age for performance is somewhere in the mid 20’s to mid 30’s, with a drop off in small, but reliable drop performance after that. Perhaps someone should tell them if they just tried harder to make more time, they’d be even stronger! (Peak Age and Performance Progression in World-Class Weightlifting and Powerlifting Athletes - PubMed , Performance Development From Youth to Senior and Age of Peak Performance in Olympic Weightlifting - PubMed , Peak Age and Performance Progression in World-Class Track-and-Field Athletes - PubMed )
  4. The above doesn’t mean that people can’t get stronger as they age, as the relative amount of strength improvement is the same between younger and older trainees. (Heterogeneity in resistance training-induced muscle strength and mass responses in men and women of different ages - PubMed)
  5. Rather, there definitely seems to be some upper limit competitive athletes begin to approach as they get closer and closer to their peak. It may be that regular folks rarely approach their limits, but I don’t think that means that limits don’t exist.
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