Difference between revisions of "Heat limited running pace"

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In hot conditions, your maximum running pace is limited by your ability to cool off. It is possible to calculate your theoretical maximum running pace at a particular temperature and humidity given your height and weight.  
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In hot conditions, your maximum running pace is limited by your ability to cool off. It is possible to calculate your theoretical maximum running pace at a particular temperature and humidity given your height and weight. This calculator is based on my [[Running Heat Model]].
 
=Introduction=
 
=Introduction=
 
When you run, you produce heat that must be removed from your body. In cold conditions, this is not a problem, but as the temperature and humidity go up, it becomes harder to remove the generated heat. If you generate more heat than you lose, your core temperature will rise and you will have to slow down. For most people, the rise in core temperature causes a gradual, though unpleasant, slow down. However, extreme dedication can force some people to push hard enough to raise their core temperature enough to cause collapse, coma and even death.  
 
When you run, you produce heat that must be removed from your body. In cold conditions, this is not a problem, but as the temperature and humidity go up, it becomes harder to remove the generated heat. If you generate more heat than you lose, your core temperature will rise and you will have to slow down. For most people, the rise in core temperature causes a gradual, though unpleasant, slow down. However, extreme dedication can force some people to push hard enough to raise their core temperature enough to cause collapse, coma and even death.  
 
=Heat limited pace table=
 
=Heat limited pace table=
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<include_PHP file="HeatMaxRunningPace" />
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=Input Form=
 
<html>
 
<html>
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<style type="text/css">
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table.imagetable {
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<form style="font-family: Helvetica,Arial,sans-serif;" method="get" action="/wiki/Heat_limited_running_pace" name="HeatLimits">
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font-family: verdana,arial,sans-serif;
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  <table style="text-align: left;" border="1"
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font-size:11px;
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cellpadding="1" cellspacing="1">
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color:#333333;
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    <tbody>
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border-width: 1px;
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      <tr>
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border-color: #999999;
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        <td>Height</td>
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border-collapse: collapse;
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        <td>
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}
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        <table style="text-align: left;" border="0" cellpadding="0" cellspacing="0">
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table.imagetable th {
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          <tbody>
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background:#b5cfd2 url('cell-blue.jpg');
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            <tr>
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border-width: 1px;
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              <td><input maxlength="3" size="3" name="Height" value="70"></td>
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padding: 8px;
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              <td>
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border-style: solid;
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              <select name="HeightUnits">
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border-color: #999999;
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              <option selected="selected">Inches</option>
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}
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              <option>Centimeters</option>
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table.imagetable td {
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              </select>
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background:#dcddc0 url('cell-grey.jpg');
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              </td>
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border-width: 1px;
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            </tr>
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padding: 8px;
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          </tbody>
−
border-style: solid;
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        </table>
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border-color: #999999;
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        </td>
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}
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      </tr>
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</style>
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      <tr>
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        <td>Weight</td>
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        <td>
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        <table style="text-align: left;" border="0" cellpadding="0" cellspacing="0">
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          <tbody>
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            <tr>
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              <td><input maxlength="3" size="3" name="Weight" value="135"></td>
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              <td>
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              <select name="WeightUnits">
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              <option>Kg</option>
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              <option selected="selected">Pounds</option>
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              </select>
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              </td>
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            </tr>
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          </tbody>
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        </table>
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        </td>
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      </tr>
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      <tr>
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        <td>Temperature Units</td>
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        <td>
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        <table style="text-align: left;" border="0" cellpadding="0" cellspacing="0">
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          <tbody>
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            <tr>
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              <select name="TempUnits">
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              <option>Centigrade</option>
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              <option selected="selected">Fahrenheit</option>
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              </select>
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              </td>
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            </tr>
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          </tbody>
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        </table>
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        </td>
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      </tr>
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      <tr>
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        <td>Temperature Increment</td>
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        <td>
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        <table style="text-align: left;" border="0" cellpadding="0" cellspacing="0">
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          <tbody>
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            <tr>
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              <select name="TempInc">
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              <option>Fine</option>
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              <option selected="selected">Course</option>
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              </select>
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              </td>
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            </tr>
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          </tbody>
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        </table>
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        </td>
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      </tr>
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    </tbody>
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  </table>
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  <input type="submit" name="mysubmit" value="Generate" />
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</form>
 
</html>
 
</html>
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<include_PHP file="HeatMaxRunningPace" />
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 +
 
 
=Heat Acclimation Training=
 
=Heat Acclimation Training=
 
''Main article: [[Heat Acclimation Training]]''  
 
''Main article: [[Heat Acclimation Training]]''  
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Heat Acclimation can improve your ability to keep cool by sweating more and sweating earlier, as well as making your sweat more dilute. Heat adaptation can also teach you the warning signs of an elevated core temperature so you can adjust your pace or take action to cool off before things get dangerous. However, heat adaptation does not change the limits of physics, nor does it allow you to tolerate a higher core temperature.
 
Heat Acclimation can improve your ability to keep cool by sweating more and sweating earlier, as well as making your sweat more dilute. Heat adaptation can also teach you the warning signs of an elevated core temperature so you can adjust your pace or take action to cool off before things get dangerous. However, heat adaptation does not change the limits of physics, nor does it allow you to tolerate a higher core temperature.
  
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=Basic Heat Calculation=
 
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The basic heat calculation is from
 
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# Heat produced from running. This is dependent mainly on your weight.
 
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# Heat lost (or gained) from convection. This is mostly dependent on your surface area (calculated from weight and height), and the air temperature.
 
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# Heat lost (or gained) from radiation. This is mostly dependent on your surface area and the air temperature.
 
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# Heat lost from evaporation of sweat. This is mostly dependent on your surface area, the air temperature and humidity.
 
 
=Important caveats=
 
=Important caveats=
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The calculations of maximum pace make lots of assumptions. This means that the pace indicated may not be safe.
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In addition to the caveats in [[Running Heat Model]], the calculations of maximum pace make extra assumptions. '''This means that the pace indicated may not be safe'''.  
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* This is the maximum pace based on the limits of heat; there are other limiting factors that mean you may not be able to achieve these paces.
 
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* Your running efficiency may be different to the average. A higher efficiency will produce less heat at a given pace, a lower efficiency will produce more heat.
 
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* The only air movement is assumed to be from running through still air.
 
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** Any wind can make a significant difference, with a headwind or crosswind cooling your off. A tailwind less than twice your running pace will reduce your cooling; it takes a tailwind of at least twice your running pace to cool you off more than still air, but of course a tailwind will reduce the energy required to run.
 
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* The calculations assume negligible clothing. If you are wearing more than the absolute minimum clothing, this will impair your ability to cool off.
 
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* It is possible to actively cool off with ice, which will allow you to tolerate higher temperatures.
 
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* Any direct sun will increase the heat stress and dark clothing will make this worse.
 
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=Advanced notes on calculations=
 
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These notes are for those with an interest in the underlying details.
 
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* There are multiple formulas for calculating water vapor pressure which produce slightly different results.
 
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* The calculation of skin temperature is not straightforward. The calculator uses Neilson's approach rather than the Mehnert formula.  
 
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* The maximum running pace is calculated using a goal seek algorithm.
 
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* The various formulas for calculating the surface area of the skin appear to give similar results.
 
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=References=
 
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This calculator is based on [http://www.ncbi.nlm.nih.gov/pubmed/8784753 Olympics in Atlanta: a fight against physics] and [http://www.ncbi.nlm.nih.gov/pubmed/10048634 Advantages of a smaller bodymass in humans when distance-running in warm, humid conditions]
 
 
=See Also=
 
=See Also=
 +
* Running calculators
 +
** [[Running Heat Model]]
 +
** [[Perceived Temperature For Runners]]
 +
** [[Optimum Running Temperature]]
 
* [[Running in the Heat]]
 
* [[Running in the Heat]]
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* [[Perceived Temperature For Runners]] (An experimental chart)
 
 
* [[Heat Acclimation Training]]
 
* [[Heat Acclimation Training]]
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* [[Impact of Heat on Marathon Performance]]  
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* [[Impact of Heat on Marathon Performance]]
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* [[VDOT Calculator]] which adjusts for heat
 

Latest revision as of 07:39, 13 November 2011

In hot conditions, your maximum running pace is limited by your ability to cool off. It is possible to calculate your theoretical maximum running pace at a particular temperature and humidity given your height and weight. This calculator is based on my Running Heat Model.

1 Introduction

When you run, you produce heat that must be removed from your body. In cold conditions, this is not a problem, but as the temperature and humidity go up, it becomes harder to remove the generated heat. If you generate more heat than you lose, your core temperature will rise and you will have to slow down. For most people, the rise in core temperature causes a gradual, though unpleasant, slow down. However, extreme dedication can force some people to push hard enough to raise their core temperature enough to cause collapse, coma and even death.

2 Heat limited pace table

The table below shows an example set of maximum running paces for someone who is 174cm/70inches high and weighs 60Kg/132lbs. You can create a customized version of this table by filling in the form below

0%10%20%30%40%50%60%70%80%90%100%
50f/(10c)UnlimitedUnlimitedUnlimitedUnlimitedUnlimitedUnlimitedUnlimitedUnlimitedUnlimitedUnlimitedUnlimited
55f/(12.8c)UnlimitedUnlimitedUnlimitedUnlimitedUnlimitedUnlimitedUnlimitedUnlimitedUnlimitedUnlimitedUnlimited
60f/(15.6c)UnlimitedUnlimitedUnlimitedUnlimitedUnlimitedUnlimitedUnlimitedUnlimitedUnlimitedUnlimitedUnlimited
65f/(18.3c)UnlimitedUnlimitedUnlimitedUnlimitedUnlimitedUnlimitedUnlimitedUnlimitedUnlimitedUnlimitedUnlimited
70f/(21.1c)UnlimitedUnlimitedUnlimitedUnlimitedUnlimitedUnlimitedUnlimitedUnlimitedUnlimitedUnlimited4:25
75f/(23.9c)UnlimitedUnlimitedUnlimitedUnlimitedUnlimitedUnlimitedUnlimitedUnlimited4:245:015:47
80f/(26.7c)UnlimitedUnlimitedUnlimitedUnlimitedUnlimitedUnlimited4:074:485:396:488:21
85f/(29.4c)UnlimitedUnlimitedUnlimitedUnlimitedUnlimitedUnlimited4:446:339:34 >14:00 >14:00
90f/(32.2c)UnlimitedUnlimitedUnlimitedUnlimitedUnlimitedUnlimited5:378:36 >14:00 >14:00 >14:00
95f/(35c)UnlimitedUnlimitedUnlimitedUnlimitedUnlimited4:287:0212:40 >14:00 >14:00 >14:00
100f/(37.8c)UnlimitedUnlimitedUnlimitedUnlimitedUnlimited5:169:40 >14:00 >14:00 >14:00 >14:00

3 Input Form

Height
Weight
Temperature Units
Temperature Increment


4 Heat Acclimation Training

Main article: Heat Acclimation Training

Heat Acclimation can improve your ability to keep cool by sweating more and sweating earlier, as well as making your sweat more dilute. Heat adaptation can also teach you the warning signs of an elevated core temperature so you can adjust your pace or take action to cool off before things get dangerous. However, heat adaptation does not change the limits of physics, nor does it allow you to tolerate a higher core temperature.

5 Important caveats

In addition to the caveats in Running Heat Model, the calculations of maximum pace make extra assumptions. This means that the pace indicated may not be safe.

6 See Also

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