Chronic Cardio is healthy?

In our little paleosphere endurance exercise is usually characterised as a "bad" thing.  Mark Sission's Chronic Cardio post is the usual basis for all this, but there are other references too.  In general I agree with this view.  However sometimes other bits and pieces pop up that indicate a different viewpoint.  I saw this one the other day:

Autophagy-related and autophagy-regulatory genes are induced in human muscle after ultraendurance exercise

The purpose of this study was to evaluate whether ultra endurance exercise changes the mRNA levels of the autophagy-related and autophagy-regulatory genes. Eight men (44 ± 1 years, range: 38–50 years) took part in a 200-km running race. The average running time was 28 h 03 min ± 2 h 01 min (range: 22 h 15 min–35 h 04 min). A muscle sample was taken from the vastus lateralis 2 weeks prior to the race and 3 h after arrival. Gene expression was assessed by RT-qPCR. Transcript levels of autophagy-related genes were increased by 49% for ATG4b (P = 0.025), 57% for ATG12 (P = 0.013), 286% for Gabarapl1 (P = 0.008) and 103% for LC3b (P = 0.011). The lysosomal enzyme cathepsin L mRNA was upregulated by 123% (P = 0.003). Similarly, transcript levels of the autophagy-regulatory genes BNIP3 and BNIP3l were both increased by 113% (P = 0.031 and P = 0.007, respectively). Since upregulation of these genes has been related with an increased autophagic flux in various models, our results strongly suggest that autophagy is activated in response to ultra endurance exercise.

Autophagy is usually presented as a "good thing" - the self eating process by which cells clean themselves up, getting rid of waste products and some pathogens.  Often it is promoted by fasting and again in the paleo world it is one of the benefits that are claimed for intermittent fasting.  I've probably written about that in the past somewhere.

Anyway, this study seems to link it to ultraendurance exercise.....actually it is talking epigenetics as far as I can see, particular autophagy related genes being switched on.  I suppose this might make sense if the exercise has actually cause massive damage and the body is frantically trying to clear up and repair the mess.  Maybe not so positive.