Depends what you mean by "serious athlete". It is true that high level athletes in sports like football and boxing often do pay the price in terms of health years later. But that has more to do with the stresses of the sport itself rather than the training. And athletes in most sports have longer life expectancies than that of the general population.
Besides which, the topic is training hard, not training for any specific sport.
Even the oldest of senior citzens can benefit from strength training (although the strength training would be different for someone who's very elderly than for someone's who's 24, 55 or whatever). Numerous studies have supported this, and shown increased independence, mobility, and decreased likelyhood of falls for seniors.
Furthermore, as mentioned in my previous post, my Grandfather is 77, is still capable of walking several miles easily (and fast) while carrying groceries and/or books, can chop wood, do carpentry, can still run (though he's not a runner), and has a grip that's still stronger than my own. And the muscle is certainly not gone. And this is despite being a diabetic, celiac, lactose intolerant, and having hypothyroidism. My great Uncle, who's 90, golfs regularly, and walks the full course. So the idea that you're lucky to be able to walk a mile or swim some laps at 60 or 70 is complete BS. For more examples read this:
http://rosstraining.com/blog/category/the-blog/age-related/ *note, in this link is a video of a man, at 70, deadlifting 650lbs.
Can we all age so well? Probably not...undoubtedly there's genetic factors or lifestyle factors that we have no control over, or injuries that aren't preventable, and can't be fully recovered from. But that doesn't mean you don't even try, or that you quit when you reach a snag.
Furthermore, the loss of muscle is only accelerated by not lifting weights and training hard, and can be slowed or reversed through lifting, especially heavy lifts, as it's the muscle fibers with the higher recruitment thresholds that are predominantly lost with age.
Lastly...why not read about the matter, instead of laboring under preconceptions that stem from (1) people making excuses and assumptions, and (2) the old incorrect school of thought which viewed that rest, and taking it easy was the best way to treat various chronic problems/diseases like cardiovascular disease, back problems etc.
It's actually only been three years since i was in Vegas. And I'll get it next time - the point is that my memory from that trip is sullied by regret. A small regret makes a big difference, is the point.
