Lactic acid doesn’t make muscles sore

Lactic acid doesn’t slow us down when we’re running. The body burns it as fuel. It does not hang around and make our muscles sore: that’s likely caused by microscopic muscle tears. George A. Brooks, a professor in the department of integrative biology at the University of California, Berkeley, has provided the new evidence: “Lactic acid is… fuel” by Gina Kolata.

Retrotransposons explained

Prof. Larry Moran over at Sandwalk explains “Retrotransposons.” RNA viruses are sneaky little things that insert foreign DNA into our genomes. This is my chance to understand those jokes about Gag, Pol, and Env.

Could retroviruses be why a sizeable fraction of humans have mouse tumour genes in their DNA, which makes them more susceptible to breast cancer?

Here’s mention of a paper: Clark, L.A., J.M. Wahl, C.A. Rees and K.E. Murphy (2006). “Retrotransposon insertion in SILV is responsible for merle patterning of the domestic dog.” Proceedings of the National Academy of Sciences of the USA 103: 1376-1381. (Also SINE insertion in SILV gene.)

Record heat halts Chicago Marathon

In today’s Chicago Marathon, 45,000 runners were registered. Hot, muggy weather was predicted. Ten thousand runners chose not to start. The race organizers did what they could. Compared to last year, they provided 10 more buses to take “drop-outs” back to the finish line and 15 more “cooling buses” for those who needed treatment, as well as 10,000 more servings of water or sports drinks. There were 700 medical volunteers, including 100 doctors.

Almost 36,000 runners started out in the hottest temperatures in thirty years: 88°F (31°C). Heat and humidity are a vicious combination. There were 10,934 DNFs (Did Not Finish). One man collapsed and died at the 18th mile of the 26-mile course. Even more surprising, almost one percent of the runners were taken to hospital or treated in the medical tents. The race started at 8:00 a.m. and the fastest runners finished, but anyone who didn’t reach the half-way point by about noon was told to get off the course and start walking back to the finishing area. Then those who had passed the half-way point were told that the race was over and they should simply stop and go straight to the recovery tents or post-race snacks.

The Army Ten-Miler in Washington, D.C., today had 26,000 runners registered. Officials thought they were ready for 70°F temperatures and high humidity with extra fluids and aid stations. Yet another runner died in that race.

It is very unusual for a runner to die like that. It made the news once when a runner had a heart attack during a race – I forget now whether it was Chicago or New York. But I calculated that in an ordinary population of that size, four people would have heart attacks during the same hours.

This article on heat exhaustion and heatstroke, “Evaluation and Treatment of Heat-related Illnesses,” by Randall K. Wexler, mentions runners:

marathon runners have developed temperature elevations up to 41°C (105.8°F) while running in 25°C (77°F) weather.

The article says that heat illnesses “occur insidiously but progress rapidly.”

I watched the 1999 Philadelphia Marathon, which was run in November with 100% humidity. Some say the temperatures were in the 60s, others that they were in the low to mid 70s. It felt like at least 80°F (26°C). I was too hot just standing on the sidelines. The runners were much worse off. By the half-way point runners were struggling and many were vomiting. But it didn’t reach the dangerous levels of today’s race, as you can see by the heat index chart below.

You can read more about today’s Chicago Marathon in The Chicagoist: Triumph and Tragedy at Chicago Marathon. And you can find more news and pictures at Chicago Tribune Sports.

One of the news articles commented that runners prefer weather of 40 – 50°F (5 – 10°C) because they generate so much heat when running. My favourite weather for running is at least that cold, preferably with some wet snow.

Spandrels and belly-buttons…

The Evilutionary Biologist’s Citation Classic this week is “The Spandrels of San Marco and the Panglossian Paradigm: A Critique of the Adaptationist Programme,” by Stephen Jay Gould and Richard C. Lewontin. The Evilutionary Biologist says:

Despite my misgivings about Gould, I found the paper on the Adaptationist Programme to be spot on. …the paper addressed a real concern in evolutionary biology…. the study of adaptation in the ’70s still suffered from wishy-washy, uncritical thinking (Larry Moran [of Sandwalk] might argue still does today!). The problem was Just So stories (so named after the Kipling kiddie stories about How the Leopard Got His Spots etc.) where anyone can invent reasons, however fanciful, for why certain phenotypic traits exist.

Hop on over for a discussion of what, why, and why not. (Hat tip to Pharyngula)

%d bloggers like this: