Sir Roger Bannister once said, “Experiments in the laboratory are not of much practical value to athletes.” We have had hot temperatures this summer and the heat also put a distinctive stamp on the 2012 Boston Marathon. I will share my strategy as it applies to recreational summer running too.

With temperature forecast for 90 degrees, emails went out to all participants offered deferments for the following year, and encouraged all but the fittest runners to participate. “This is the year for experiencing, not racing the Boston Marathon” was the message.

Even more prudently, the race committee also issued the statement “Good hydration is important, but overhydration is dangerous.” In other words, drinking too much water is not only unhealthy, but potentially fatal.

Winning times for men and women were over nine minutes slower than 2011. The sun is a powerful brake through radiant heat. With shade temp at 90, the road temp in the sun was 10 to15 degrees warmer. Many of the elite frontrunners did not finish. Last year’s record-breaking winner Geoffrey Mutai dropped out after 18 miles with stomach cramps.

I played it safe and finished nine minutes slower than last year’s time, yet came away with fourth in my age group (45-49). More importantly, I avoided the medical tent by following good racing practices. I wasn’t there to see how fast I could run, but to enjoy myself and soak up the terrific vibes of the race.

In the preceding days before the race good karma was passed on to me over a coffee with 1984 women’s winner Lorraine Moeller and 1976 winner Jack Fultz. The 1976 race started in near 100-degree heat and was known as “Run for the Hoses” as spectators used garden hoses to cool runners down. It should be noted that even then it was the “Run for the Hoses,” not the Gatorade nor water stations. Common practice in 1976 was not to drink beyond thirst.

Lorraine Moller shared her pre-race cooling strategy before the Barcelona Olympics where she won bronze. Her manager found a local home where the team could take cold showers before the race while competitors waited at the start in the heat. Later, Deena Kastor and Meb Kezflezighi would use higher tech cooling vests before their Olympic medal performances. I did the low-tech cooling by relaxing at a family friend’s house in Hopkinton and pouring an ice cold bottle on my head before the start.

I didn’t drink very much during the race, maybe 12 to16 ounces of water, but repeatedly cooled down by pouring water over my head and body. The primary cooling is evaporative and thankfully the humidity was low enough for this to happen. In April the body has not yet fully developed the sweat mechanisms. Too often, runners mistakenly think that drinking a copious amount of water will lower the body’s core temperature; however, over drinking won’t cool you down.

Although it was my 19th time running Boston, like many in this year’s race I was totally overwhelmed by the generosity and kindness of spectators who lined the streets with water and hoses for cooling. These weren’t official volunteers. They were family, kids, and students, all eager to help runners in the heat. Better yet, because the water was coming from peoples’ homes, it was cold much colder than the aid stations. I’d douse myself with the water from these impromptu aid stations and find a new burst of energy.

Here are some take away messages based on the science of cooling and how we evolved. Historically the best performers end a race in what many would clinically call “dehydration” . But they are not ill, just appropriately warm and tired and in need of some recovery. Ingrained human behavior of “I am hot and must drink more” is wisely being replaced with “I am thirsty, so I should drink.” We evolved to run for hours in the sun without an aid station every mile.

Some “dehydration” (used quotes as this is a non clinical term with no real definition) is normal and humans developed favorable biological adaptations that permit prolonged running in the heat. Dangerous heat stroke occurs more frequently in shorter events when the body’s engine is on high. Body temperature exchange is a balance of metabolic heat production and the exchange with the environment. It has little to do with hydration.

We are designed to run (albeit maybe not race) in the heat and are the best warm weather runners on the planet. Understanding this helps our cooling strategy and pacing. Running on two feet reduces our surface area to the sun and gets us off the hot surface of the ground. As we get warmer, more blood is diverted to the skin for cooling, thus a pace reduction is needed. We have an innate sense of fatigue and warmth and our brain will shut off motor units when too warm. Be self-aware and do not override this. Modern day persistence hunters will run two to six hours at easy paces with very little water. If they needed to stop for water they’d have to give up the chase. Our lack of fur and smooth skin facilitate sweating. We run with relatively small muscles and long springs of our tendons, an efficient stride that benefits us in the heat.

Here are a few modern day strategies which complement our evolutionary human properties.

Pre-cool as best you can before a run. An ice cold towel, an electrolyte popsicle, a cold bottle to pour and carry, finding shade, and not “warming up” can all be applied.

Keep the body wet for evaporative cooling. Pour water on the large body surface areas. Sunscreen can bead the sweat and fluid and it just rolls off you so use this sparingly to prevent burn in key areas only.

Radiant heat transfer from the sun is huge. We all feel this. So find shade if you can.

Drink when you are thirsty and know your body. Do not drink to replace every ounce lost. You will lose fluid. We are designed to do this safely as long as we replace later at a meal.

Slow your pace . An 8 minute mile might become a 10 minute mile at the same effort.

Dress white and light and expose skin for evaporation.

Use electrolytes if you are going to be sweating and replacing fluids for over three hours. Electrolytes will help maintain better fluid balance. You can drink sports beverages to get your electrolytes or you can use electrolyte tablets, gels, or powdered mixes.

Acclimatization works. In 7 to14 days of running in heat your body makes magical adaptations, so go easy and be patient.

Do not run in the heat if you are poorly conditioned, have existing medical problems, are taking prescription medications which affect heat regulation, use dietary supplements (especially stimulants), or have a history of heat illness.