4-7-15

“In response to endurance training and repeated demands on the heart
and circulatory system, the heart itself must become stronger and more efficient. Unlike resistance training, which simply enlarges part of the
wall of the heart (left ventricle) in response to brief and acute increases
in cardiac load, cardiovascular training strengthens the entire heart, and most importantly, increases the vascular network that delivers blood to the heart itself (the heart itself doesn’t just get blood from what it pumps – it, of course, has to pump blood to its own arteries as well, and this vascular network that fuels it is critical to allowing it to sustain stronger, faster contractions for an extended period of time).

*****Along with the improved vascular network, the heart’s stroke volume (blood pumped per contraction) is increased – this adaptation requires extended full ventricular filling (Frank-Starling mechanism), which as mentioned tends to occur in the moderate aerobic range (70-85% of MHR) – high intensity training, including weight training, does not seem to trigger this same increase in contractility, and therefore may not result in the same adaptation.*****

The primary reason that these stressors are different: During resistance training/HIIT, a combination of muscle occlusion and the valsava maneuver (straining) actually increase blood pressure but occludes venous return; in other words, since everything is tensed during every repetition or short interval, no blood is flowing during muscular contraction, and less is flowing into the heart. When an individual is running or biking, this isn’t the case, venous return is actually increased. In essence, with weight training, though the heart rate is increasing, it’s not necessarily pumping more blood. With cardiovascular training, it is.”

I hope that the above literature explains a little why, we should slow down  so that we can speed up. See you tomorrow