How do you run 26.2 miles if you have trouble making it around the block? With good coach­ing, discipline, and lots of group support, as NOVA shows when it follows 13 generally sedentary people through a training regimen designed to prepare them for an ultimate test of stamina and endurance. Created in cooperation with the Boston Athletic Association®, which granted NOVA unprec­edented access to the 111th Boston Marathon®, and Tufts University, “Marathon Challenge” takes viewers on a unique adventure inside the human body, tracking the physiological changes that exercise can bring about.

Zatopek worried he had lost fitness. That was not the case, however. On race day Zatopek felt great. Fully rested, his strong body had finally absorbed the countless miles he had put in through the forests surrounding Prague. He won the gold at the European 10,000 meters, finishing with the world’s second-fastest time.

From then on, such a forced rest before a race has been known as “the Zatopek Phenomenon.”

For more info on tapering for your next race read the rest of this article.

Marathon running might be in some people’s genes, according to a new study, which shows that a genetic mutation that boosts muscle endurance has spread widely in some human populations.

There are two types of skeletal muscle fibers. Fast fibers, which use sugars for fuel and do not require oxygen, kick in for tasks that require maximum force and quick action, such as sprinting. Slow fibers, which employ oxygen-using (or aerobic) pathways, power activities that require endurance, such as long-distance running. A protein called alpha-actinin-3 is made mostly by fast fibers and is implicated in their capacity for rapid force generation. About 18% of people of European descent do not produce the protein at all due to mutations in both their copies of the gene ACTN3, which codes for alpha-actinin-3. Previous studies have shown that endurance athletes such as long-distance runners have higher frequencies of this mutation, whereas sprinters and athletes in other sports that require quick muscle strength have lower frequencies.

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One possibility, Dr. Chediak said, is that cytokines — hormones that signal the immune system — are making these athletes sleep so much.

Exercise, Dr. Chediak said, prompts muscles to release two cytokines, interleukin 6 and tumor necrosis factor alpha, that make people drowsy and prolong the time they remain sleeping. In fact, those cytokines also are released when people have a cold or infection, which is why people sleep so much when they are ill.

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