> You could argus that there is a difference between physical and mental focus ... Not only that, developing software is generally a "slow" task, not constant

> You could argus that there is a difference between physical and mental focus ... Not only that, developing software is generally a "slow" task, not constant decision making in spans of milliseconds like in a "fast" sport you mentioned. If you want to compare, try a "slow" sport like golf, does your observation still hold true? In engineering tasks you also gain a lot of productivity (at least if your metrics aren't crap, might be often a problem here) from years and decades of building up experience and knowledge. Moreover this doesn't get lost to a huge degree if you pause 1-2 years, not like physical training which goes away quickly and is hard to build up again. I think what could play a role here is that older people may often be less focused on the job because that focus shifts to other things in life like e.g. family.