NYT blogged about this new find with the title 'When Exercise Is Too Much of a Good Thing'. However they concluded with the following positive statement:
"But if you exercise regularly and currently have no symptoms, “I think it’s safe to say that you should keep it up,” Dr. Thompson said."That's also what Chris Carmichael thinks according to his blog: 'Too Much of Good Thing? Hardly.', where he sums his personal views very encouragingly for us about 50 years old endurance athletes:
"But for me the health, performance, social, and psychological benefits of being a life-long athlete far outweigh the risk described in the NY Times blog. Case in point: When I hit “send” on this, I’m off for a 5+ hour training ride on the Queen K Highway!"However, as Gordo Byrn points out in 'You Have a Choice', five hours per day is likely to cause illness if sustained long term. I'm sure Mr. Carmichael didn't plan to work out as long every day either. Anyway Mr. Byrn observes that two hours per day (12-15 hours per week) on the average is his personal sweet spot for optimal athletic performance and "life benefits".
Heart disease is everywhere these days, and endurance athletes are not immune to it. Alberto Salazar is often mentioned in this context. In 'Why Did Alberto Salazar Have a Heart Attack?' his cardiologist explained what went wrong and why.
Even lifelong aerobic exercise is not likely to be a major cause of heart disease, as long as it's taken easy rather than too hard. Too much of a good thing can kill you of course, but what is exactly 'too much' will vary a lot individually. Combined with a healthy lifestyle, I believe aerobic exercise in moderation can help prevent disease and increase happiness.