"But half of the older lifelong athletes showed some heart muscle scarring. The affected men were, in each case, those who’d trained the longest and hardest. Spending more years exercising strenuously or completing more marathon or ultramarathon races was, in this study, associated with a greater likelihood of heart damage."
Um, we already get this. Read Mark Sisson for gosh sakes! To paraphrase:
Move slowly (walk/hike) quite a bit.
Sprint once in a while. Lift heavy things once in a while.
High intensity stuff should be pretty brief. Low intensity - do quite a bit.
I haven't seen a single person here recommending marathons or ultramarathons as healthy. Otoh, if that's your thing, more power to you - just be aware of the downside. I'm pretty sure most of us here are.
This NYT article reviews some recent research on the effects of high volume running on scar tissue in the heart. It focuses on long-term, always active, non-smoking runners. There is scarring in heart tissues among most if not all of them. Even rats who are made to marathon-like running and high volume training, show scarring of the heart. Scared heart muscle is more likely to go into fibrillation because the contraction pulses across the heart become more fragile and lose their coordination. A scarred muscle does not have the flexibility and contraction force, so the coordination breaks down at mutiple sites. The good news is that this is reversed, in the rats, when they are no longer made to run excessively.
I have argued that metronomic training reduces the chaos in the heart. Scarring of heart muscle is an obvious way that would occur. A scarred heart cannot have the power law variation of heart beat intervals and is more likely to lock onto periodic contraction patterns---fibrillation.
This only looked at heart muscle. Other tissues of the heart may also be damaged, particularly the valves. There is often damage in other tissues as well, ankles, knees, hips, the foot, the upper respiratory system, the kidney (which has to clear the damaged proteins), and other organs that may be but in transitory state of ischemia.
We are not against running: easy forest running with cuts and variation of pace, or sprinting a variety of distances at varying pace, if fun and easy. It is the metronomic, forced pacing and long duration of long-distance running that is unnatural. And piling up the miles is not enjoying much of anything.
I've been listening to this guy a bit lately. He is pretty vehement about limiting aerobic activity - http://www.naturalhealthpodcasts.com/PodCasts/heart_attack.mp3
He has a lot to say about fibrosis in general as well.
I tend to just listen to my body..sometimes it wants to do two hours a day of sprints,rowing machine,elliptical,and a beach hike.Sometimes,like today,it's going to tell me" &*( you, buddy.we've done enough right now.Take a nap."
One thing not brought up in the usual criticisms of chronic cardio is that most of the research was conducted under the assumption that a low fat, high carbohydrate diet is the healthiest, so that's what the subjects were eating (carb loading, trying to be vegetarian, etc.) Over the years, you can get depleted on this type of diet whether you're running marathons or not. I'd be interested in seeing a study done of paleo dieters engaging in steady state, high intensity cardio and whether the same damage occurs.
I think I was overtraining previously, and have changed my workout schedule a bit in order to address the issue.
Sun - Tabata sprints (10x 20 sec. all-out sprints w/10 sec. rests between each)
Mon, Wed, Fri - Stronglifts 5x5 program
Tue, Thu - morning calisthenics, regular walking during the day
Sat - big hike with the dog, usually some tree-climbing and driftwood-balance-beaming is involved
I am also starting an IF regimen next week with a 16 hour fast followed by an 8 hour feeding window. We'll see what happens :)