Aerobic Capacity and the Metabolic Syndrome

This news release talks about an intriguing study between aerobic capacity and heart disease.  Over 11 generations, researchers bred rats with either low or high aerobic capacity.  The group of low aerobic capacity rats scored higher on risk factors related to the metabolic syndrome, suggesting a strong link between the two.

I dug deeper and got the full-text of the original study.  First, there was some good news for the low capacity rats: there were able to significantly increase their aerobic capacity through training.  The high capacity group was able to increase their fitness through training as well, and a sizeable gap remained, but at least the low capacity group maintained the ability to improve their capacity.

Next, the authors looked at longitudinal changes in both groups of rats.  They noticed that at five weeks old, both groups of rats weighed the same and had the same amounts of visceral fat.  Therefore, the authors believed that the low aerobic capacity of the one group of rats (before training) preceded and may have actually led to the metabolic problems this group encountered.

This is quite interesting as it shows that the metabolic syndrome may be prevented by achieving a high aerobic capacity (or as high as a person can get, given their genetics).  Other lines of thought suggest that a poor diet leads to metabolic problems, which leads to diminshed activity and ultimately a diminished aerobic capacity.  This new line of thinking starts from the other end and suggests that a low aerobic capacity may be the starting point for a downward metabolic cascade.  Of course, diet can cause metabolic dysfunction, but little research has focused on the possibility that aerobic capacity may be the more important and ultimate regulator of the metabolism.

But what about the conventional wisdom that aerobic capacity unavoidably declines with age?  Personally, I think this "normal" decline has been greatly overstated.  This article shows that if a person continues with high-intensity aerobic interval training, their aerobic capacity will not drop off much over time.  And this is great news for anyone wanting to stay healthy and avoid the metabolic syndrome as they age.