No. External stimula do not alter genetics. Lysenko is long dead.
No. External stimula do not alter genetics. Lysenko is long dead.
I am not current on the details of this muscle physiology. Speed and power are both dependent on the ability to rapidly recruit motor units into contraction. This is discussed in PPST3.
Let's formulate this a little more carefully:
External stimuli cannot alter the content of someone's genes.
External factors can and do alter the expression/transcription of genes, some of which may be passed on to offspring through DNA methylation, etc.
So, the question should be something like "Does exposure to hard work/training on young children impact the distribution of fast/slow muscle fibers, through alteration of genetic expression?"
This does seem like an evolutionarily useful bit of phenotypic plasticity, but I find it highly unlikely that there is much research aiming to answer the question.
Is there any work looking at the genes that control the distribution of fiber types in muscle tissue, and so on? I've no idea.
This is the epigenetic issue: we have mapped the human genome, but are only starting to understand the various influences (environmental, behavioral, etc.) that effect its expression. DNA methylation is just one possible influence.
This article discusses the issue in the context of muscle memory: Does skeletal muscle have an ?epi?-memory? The role of epigenetics in nutritional programming, metabolic disease, aging and exercise - Sharples - 2016 - Aging Cell - Wiley Online Library
It's an interesting read, and sums the recent thought on the issue quite well.
However, the exercise stimulus that has been studied to date has almost all been aerobic "cardio."
From the paper: "There are currently little or no studies into epigenetic modulation post acute anabolic stimuli such as that of acute resistance exercise or those induced by muscle hypertrophy*via chronic resistance exercise."
There is a bunch of interesting stuff in this paper.
Firstly, a big take away is how important maternal nutrition is, in terms of how it impacts body composition of offspring (including muscle fiber type distribution).
A second is the potential life-long durability of early life epigenetic alterations of skeletal muscle.
An interesting implication that they don't really discuss much has to do the odd multinucleate structure of skeletal muscle. Early life exposure to positive/negative stresses may create a life-long "memory" in muscle nuclei. But, because satellite cells can produce new, additional nuclei in response to a training stimulus, even if those early life exposures produce very durable markers in 'original' nuclei, it may be possible to either mitigate or augment the effect of those modifications through the addition of new nuclei with a different set of epigenetic markers (and hence different response to stimuli).