Reid Forgrave at the New York Times:
There are two principal reasons for the superior conditioning of cross-country skiers, according to Laura Richardson, a clinical exercise physiologist at the University of Michigan School of Kinesiology. First, theirs is a quadrupedal sport, with arms and legs working hard at the same time, along with core and back muscles. Because the body’s cardiovascular system is not accustomed to serving those large muscle groups simultaneously at high rates of exertion, they all compete for the available blood. Over time, the body adapts by increasing blood volume, so the heart pumps more blood with each heartbeat. This sends more hemoglobin with oxygen throughout the body. As a result, most elite cross-country skiers like Diggins have an especially powerful heart muscle and an especially large and strong left ventricle to pump out more blood per minute. The mitochondria in muscle tissues — the powerhouses of the cell — in turn grow in size and in numbers to handle the rise in oxygen.
More here.
Enjoying the content on 3QD? Help keep us going by donating now.