Well according to the study national guidelines have it exactly right and moderate exercise is beneficial.
"jogging even <1 h per week or 1 time per week is associated with significant mortality risk reduction compared with sedentary"
"1 to 2.4 h of jogging per week, with a frequency of 2 to 3 times per week, at a slow or average pace is most favorable as an optimal jogging time, frequency, and speed for reducing mortality."
In the podcast commentary the researchers do agree that other equivalent types of exercise may have similar benefits.
There is also a caveat in that the the non joggers were more likely to be older, more obsess and have DM. They adjusted for that but the written editorial commentary suggests that it might still be a confounder.
How about the strenuous exercisers who had a higher death rate?
The study looked at 12 years of data . Most people who train for a long distance event don't sustain large amounts of exercise week in week without rest periods .They have times when they do less, times when they do long distances at slow pace and times when they do short distances at more intensive training.
Do these people actually end up in the strenuous category over 12 years? (I don't know, it's a genuine question that the full paper might answer)
It seems that only 40 people were categorised as strenuous joggers There were 2 deaths in this strenuous group so yes it was a high rate compared with the moderate and light joggers.
However , since the deaths considered were 'all cause' then it could be from anything (that's the same for all exercise categories but when there are only 2 deaths out of 40 then it could be important.)
Were theyrun over by a bus whilst running wearing an ipod? Did they have a heart attack at the finish line? Did they perhaps have road accidents when driving (strenuous runners may be competitive people, perhaps they are competitive on the road ) There are all sorts of possiblities
You need more data and more analysis to consider whether it was the running that increased the death rate or something else entirely.
The chart puts the figures in perspective
http://content.onlinejacc.org/article.aspx?articleID=2108914
