Central vs. Peripheral Cardiovascular Adaptations
There’s some science ahead, folks, but I’ll try to keep it interesting.
One of the things that we get asked frequently at EE is why we focus on resistance training. The short version is that, by focusing on high quality movements with resistance, we can positively affect the totality of the physiology including components that improve heart health. People have a hard time understanding this, so this post is largely about that.
The role of the heart
So why do we “need” to do cardiorespiratory training? People largely give me a tautological answer like “…Because we need to do cardiorespiratory training.” The “need” to do this has become so engrained in the zeitgeist of fitness that people accept the supposed requirement like they accept the need for oxygen in order to keep living. If you’re “fit,” you include cardiorespiratory training.
That still doesn’t answer “why.” If pressed, people then cite their heart health as the reason. Better answer. As amazing as the heart is, it’s simply a four chambered pump. Its action is modulated by the nervous system to meet the demands of any activity you’d participate in, from relaxing to high level athletics. The heart’s main role is to pump oxygenated blood to the working tissues of the body and to seamlessly meet this demand in a changing energetic environment. Put another way: your heart is there to serve your muscle tissue. Period. So we focus on improving muscle tissue at EE to make the heart healthier.
Now telling people this usually blows their minds. The assumption is that all of the changes that result in a healthier heart come from changes to the actual heart muscle. There are changes to the health muscle in high level endurance athletics to be sure; take a look at this graph:
In this case, LVID stands for “left ventricular internal dimension,” MWT stands for “Mean Wall Thickness,” and LVM stands for “Left Ventricular Mass.” It’s important to note that chronic endurance athletics (though not as much with ultraendurance athletics, paradoxically) does change the size of heart components, which generally return to normal after the athletics career has ceased. These adaptations are generally considered positive in the context of athletics.
Where the rubber meets the road is in the periphery. In this case, we’re not referring to the heart muscle but the muscle tissue and vascular structure that the heart is actually delivering oxygenated blood to and through. There is a significant amount of changes to tissue as a result of training including:
- Capillary Number & Recruitment
- Mitrochondria density
- Enzymatic activity
The last one is what I’ll focus on. First, take a look at this chart:
So when you look at that chart, you’ll see that cardiorespiratory (“aerobic”) training is associated with larger increases in enzymes that deal with the large amounts of pyruvate that such training results in. As expected, you see that anaerobic training results in substantial increases in the enzymes responsible for mobilizing ATP and increasing the accessibility of glycogen, anaerobic substrates.
Here’s the thing: if you train in a manner similar to how we do at EE, you get the best of both worlds. Studies have shown that when high intensity interval training is used, both anaerobic and aerobic enzymes increase substantially. (1, 2, 3). More muscle tissue means more of the changes discussed above and less stress on the heart at any workload. Will it make you an endurance athlete without specific training? No, but in one of the studies such training doubled endurance capacity (time to fatigue), which would come in handy during such events.
That’s a long way of saying: we use weights in an interval fashion because it builds muscle and makes your heart healthier with no time wasted. Simple, really.
Skyler Tanner is an Efficient Exercise Master Trainer and holds his MS in Exercise Science. He enjoys teaching others about the power of proper exercise and how it positively affects functional mobility and the biomarkers of aging.