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May 24, 2021 | Reverberating Science

Impact Of Weather on Running Performance

Reproduced by Rodrigo Fava Neto

This content is a reproduction of parts of the scientific article entitled “Impact of Weather on Marathon-Running”, which quantified the impact of the weather on the marathon result of different groups of runners.

The article was published in 2007, available in its entirety at the Medicine & Science in Sports & Exercise, link at the bottom of the page. If you like the excerpts I transcribed here, I recommend reading them in full.

approx. 5 minutes reading

A 42 km marathon is among the most physiologically demanding endurance races in the world. Competitive runners normally maintain a pace corresponding to 70-90% of their maximum aerobic capacity for more than 2 hours. At maximum mechanical efficiency, more than 80% of the energy required for this task is transferred as heat to the center of the body.

In addition, the rate of endogenous heat production associated with a 2 h 10 min marathon estimated from common heat balance equations is approximately 1400 kcal / hour. This metabolic heat must be dissipated into the environment, or the body temperature will rise to physiologically dangerous levels.

The body temperature is independent of the climate up to a certain temperature range. And activities involving higher metabolic rates require a smaller temperature range.

Thus, the weather begins to affect physiological responses to exercise at relatively lower temperatures during activities that generate a high metabolic rate compared to those that generate lower metabolic rates.

To avoid health hazards, the National Collegiate Athletic Association (United States) has among its guidelines the recommendation that distance running (> 16 km (10 miles)) should not be carried out when the temperature WBGT (wet-bulb globe temperature) exceeds 28 ° C (82.4 ° F).

It is important to remember that the study was done using a temperature measurement that already considers humidity, wind, and incidence of sun, the WBGT.

The thermometer we have at home does not normally consider humidity, for example, which is one of the factors that changes our perception of heat.

The human body usually cools down with perspiration or sweat. Heat is removed from the body by the evaporation of this sweat. However, the high relative humidity reduces the rate of evaporation. This results in a lower rate of removal of heat from the body, and eventual overheating.

The heat index was created to express the combined result of temperature and humidity in the body, see table below.

Heat index in Celsius, considering temperature and humidity

(U.S. National Oceanic and Atmospheric Administration)

Heat index in Fahrenheit, considering temperature and humidity

(U.S. National Oceanic and Atmospheric Administration)

The main finding of this study was that there is a progressive and quantifiable decrease in the performance of the marathon as the temperature increases from 5 to 25 ° C.

Marathon results and weather data were obtained for Boston, New York, Twin Cities, Grandma’s, Richmond, Hartford and Vancouver marathons for 36, 29, 24, 23, 6, 12 and 10 years, respectively. The race results were divided into groups based on temperature (Q1 to 10 ° C, Q2 to 15 ° C, Q3 to 20 ° C, and Q4 to 25 ° C) and compared to Q0 to 5 ° C.

In order to quantify the impact of temperature on the performance of the first places, the average time of the first three was classified. This approach revealed that elite men were 1.7 ± 1.5, 2.5 ± 2.1, 3.3 ± 2.0 and 4.5 ± 2.3% (mean ± SD) slower than the course record.

The impact is greatest on the slowest runners. The comparison of the 25th, 50th, 100th and 300th finalists with the current male course record showed that their performance time decreased by 2.6, 3.5, 4.9 and 7.9% between the first and the fourth track temperature.

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Although it is not the focus of this study, one can imagine that the basic principles of the impact of the weather apply to other sports of long duration, and even to those that are recreational.

Important: adjust expectations, practice sport with knowledge, have fun and gain health.

link to the original article.

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