Posts tagged exercise

The ultimate limit of human endurance has been worked out by scientists analysing a 3,000 mile run, the Tour de France and other elite events. They showed the cap was 2.5 times the body’s resting metabolic rate, or 4,000 calories a day for an average person. Anything higher than that was not sustainable in the long term. The research, by Duke University, also showed pregnant women were endurance specialists, living at nearly the limit of what the human body can cope with. The study started with the Race Across the USA in which athletes ran 3,080 miles from California to Washington DC in 140 days. The study found a pattern between the length of a sporting event and energy expenditure - the longer the event, the harder it is to burn through the calories. So people can go far beyond their base metabolic rate while doing a short bout of exercise, it becomes unsustainable in the long term. The study also shows that while running a marathon may be beyond many, it is nowhere near the limit of human endurance. Marathon (just the one) runners used 15.6 times their resting metabolic rate. Cyclists during the 23 days of the Tour de France used 4.9 times their resting metabolic rate. A 95-day Antarctic trekker used 3.5 times the resting metabolic rate. During pregnancy, women’s energy use peaks at 2.2 times their resting metabolic rate. “You can do really intense stuff for a couple of days, but if you want to last longer then you have to dial it back,” Dr Herman Pontzer, from Duke University, told BBC News. “Every data point, for every event, is all mapped onto this beautifully crisp barrier of human endurance. "Nobody we know of has ever pushed through it.” The researchers argue the 2.5 figure may be down to the human digestive system, rather than anything to do with the heart, lungs or muscles. They found the body cannot digest, absorb and process enough calories and nutrients to sustain a higher level of energy use. The body can use up its own resources burning through fat or muscle mass - which can be recovered afterwards - in shorter events. But in extreme events - at the limits of human exhaustion - the body has to balance its energy use, the researchers argue.

via https://www.bbc.com/news/health–48527798

Implicit in the research is a new indictment of the Western diet. Not only do highly refined foods present tremendous caloric excess, they lack these salutary signals from the plant world—“signals that challenge,” Mattson says. Those signals might otherwise condition our cells in a way that prevents disease. Another variant of the hormetic idea holds that our ability to receive signals from plants isn’t reactive and defensive but, in fact, proactive. We’re not protecting ourselves from biopesticides so much as sensing plants’ stress levels in our food. Harvard scientist David Sinclair and his colleague Konrad Howitz call this xenohormesis: benefitting from the stress of others.

http://nautil.us/issue/15/turbulence/fruits-and-vegetables-are-trying-to-kill-you

Although she writes, “I would not dream of denying the evolutionary heritage present in our bodies,” Zuk briskly dismisses as simply “wrong” many common notions about that heritage. These errors fall into two large categories: misunderstandings about how evolution works and unfounded assumptions about how paleolithic humans lived. The first area is her speciality, and “Paleofantasy” offers a lively, lucid illustration of the intricacies of this all-important natural process. When it comes to the latter category, the anthropological aspect of the problem, Zuk treads more gingerly. Not only is this not her own field, but, as she observes, it is “ground often marked by acrimony and rancor” among the specialists themselves.

http://www.salon.com/2013/03/10/paleofantasy_stone_age_delusions/