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running in heat vs letting it cool slightly (Read 1691 times)

    quick google search regarding my earlier post...

    http://www.islandnet.com/~see/weather/life/heat.htm

     

    How The Body Reacts To Excess Heat

    When blood is heated above 37° C (98.6° F), the human body attempts to lose the extra heat by losing water through the skin and sweat glands, altering the rate and depth of blood circulation and, as a last resort, by panting. As body temperature rises, the heart rate increases and blood vessels dilate to increase blood flow from the body's core to the skin's surface. There, the blood is circulated through tiny capillaries threading around the upper layers of skin, and some excess heat drains off into the hopefully cooler atmosphere. At the same time, water moves from the blood through the skin, a process we refer to as perspiration or sweating. About 90 percent of the body's heat is lost through the skin, and most of that is lost through perspiration. When the air temperature is greater than 37° C, heat can only be lost through sweating.

    Sweating by itself, however, does nothing to cool the body unless the water is removed by evaporation. In order to evaporate the sweat from the body, heat energy is required to change liquid water into the vapour state: 540 calories of heat energy per gram of water to be exact. That heat of vaporization is contributed by the body to the water -- that is where the cooling comes from. However, some water vapour also condenses back onto the body returning those 540 calories per gram of heat in the process. If the rate of evaporation exceeds the rate of condensation, the body will cool. The concentration of water vapour in the air, the humidity, is a prime factor in determining the degree of evaporative cooling.

    Those who inhabit the areas affected by both heat and humidity often wonder about the relative comfort of desert heat, which exceeds 40° C (104° F). The answer lies in the water vapour content of the air: the humidity. In a hot, dry environment, more heat can be lost through evaporation than regained through condensation and the body cools.

    When the humidity is high, however, much of the heat lost is countered by an almost equal heat gain. Thus the cooling of the body is minimal, leading to overheating. And overheating can cause discomfort at the very least and death at the very worst. Continued loss of water and a variety of dissolved chemicals such as sodium chloride -- salt -- from the body, if not replenished, can cause dehydration and chemical imbalances. Dehydration depletes the body of water needed for sweating and thickens the blood, requiring more pressure to pump it through the body, thus straining the heart and bllod vessels. In addition, the increased heart rate and blood flow may harm or kill those with heart or circulatory diseases. Research on the effects of heat and humidity on humans has shown the severity of heat disorders increases with age. Conditions which cause heat cramps in a 16-year old may cause heat exhaustion in a 40-year old and heat stroke in someone over 60.

    2014 Goals:

    #1: Do what I can do. <DOING>

    #2: 365 Hours training <NOPE, INJURED>

     


    Feeling the growl again

      In other words....much of that high HR and rapid breathing that is associated with effort due to running in cooler weather, is instead due to the body's attempts to cool itself during hot weather.  So while the effort and signals say you're working as hard or harder the amount you are putting into the running probably isn't, and some signals (BR, breathing) that signal higher aerobic effort in cooler weather are partly signalling cooling attempts in hotter weather.

       

      Good stuff.

      "If you want to be a bad a$s, then do what a bad a$s does.  There's your pep talk for today.  Go Run." -- Slo_Hand

       

        I was wondering about the panting part at under 80-85 % of my Max HR, when I know I don't breath so hard in races when my HR is much higher.  Now I know it's probably a last resort to cool down when running in 90 degree humid weather.

          The physiology is interesting, but it doesn't take a Ph.D in physiology to figure these things out. All it takes is a summer of training in the heat--it's harder, and the payoff is less.

            I know my body didn't react well to the heat and 10K race I ran Monday.  Things I experienced...dead legs, burning skin, chills, and total exhaustion.  After the race I was disappointed in myself for actually stopping for the first time ever during a race and walking some instead of pushing through it.  After thinking more about the race later that night, I think I did the right thing. 


            Feeling the growl again

              The physiology is interesting, but it doesn't take a Ph.D in physiology to figure these things out. All it takes is a summer of training in the heat--it's harder, and the payoff is less.

               

              But you feel like superman when it cools down again.  Total context game on the mind, but it may lead one to THINK it did a lot more than it did.

               

              I'll take training hard over the winter and racing in the spring over trying to train through the summer heat and race in the fall, however.  I'm getting too old for that.

              "If you want to be a bad a$s, then do what a bad a$s does.  There's your pep talk for today.  Go Run." -- Slo_Hand

               

                I'll take training hard over the winter and racing in the spring over trying to train through the summer heat and race in the fall, however.  I'm getting too old for that.

                 

                +1

                www.hplg.net  The Human Powered League - Solo Cup Series - Trail Building


                Marquess of Utopia

                  Just from experience I dread the humidity. I really don’t look at the temperatures anymore; I look at the dew point. This has been one on the toughest years I can remember; the dew point is rarely below 70 degrees and has been as high as 80 degrees. I don’t think the relative humidity is helpful either. 55-60 degrees and 100% humidity is ok while 85 degrees and 72% humidity (dew point at 75) is awful and an easy/recovery pace is tough.

                   

                  I went for a long run at a pace that I should have been able to easily manage it was a nice over cast day I had plenty of places to hydrate with Nuun tablets, but I still felt a part the last 6 miles. 75 degrees shouldn’t feel that bad, but with a dew point of 75… it sucked.

                   

                  This my heat index calculator designed for runners:

                   

                  If (dewPoint > 55 degrees)

                   

                  {

                   

                                  RunningFeelsLikeTemp = Temp + (dewPoint – 55)

                   

                  }

                   

                  Else

                   

                  {

                   

                                  RunningFeelsLikeTemp = Temp

                   

                  }

                   

                  So running on 95 degree day and the dew point is at 80 degrees will feel the same as a 120 degree day in Phoenix, AZ.

                    10:30am local time in Dallas.

                     

                    Current Temperature: 95*

                    Dew Point: 67*

                    Therefore, the "Feels Like" temperature is 107* (and it's only 10:30)....

                    2014 Goals:

                    #1: Do what I can do. <DOING>

                    #2: 365 Hours training <NOPE, INJURED>

                     

                      But you feel like superman when it cools down again.  Total context game on the mind, but it may lead one to THINK it did a lot more than it did.

                       

                      I'll take training hard over the winter and racing in the spring over trying to train through the summer heat and race in the fall, however.  I'm getting too old for that.

                       

                      I did it last year, but actually I think it was only because I was in really good shape going into summer training that I was able to pull it off. And despite training pretty hard and consistently, I didn't see tons of gains.

                       

                      This year has been tougher, but I think it's more a matter of motivation and simply not being in great shape.

                      xor


                        Or you could just be old now.

                         

                         

                        That there is a joke.

                         

                        I'll be in Dallas next week.  Gonna run 50k around a park.  At least that will be at night.

                         

                          Or you could just be old now.

                           

                           

                          That there is a joke.

                           

                          I'll be in Dallas next week.  Gonna run 50k around a park.  At least that will be at night.

                           

                          Ha, yeah, I ran in Houston for a year. Brutal!

                           

                          Sometimes I think that sensitivity to the heat is less about how old you are and more about how many times you've experienced heat exhaustion or stress. But that's purely speculative.

                            Thanks, Spaniel, for the summary!! ;o)  I wasn't going to read the whole "excess heat" stuff because, actually my point of previous post being, I really don't think it matters that much.  I always felt that, in the heart of MN winter, we probably nurt more calories running outdoor because our body probably burns more calories just to stay warm; and also during the summer if I have to walk (as the alternate workout when injured), I'd wear extra clothes because, that way, my heart will probably be beating extra and so you are actually getting some training benefits.

                             

                            That said, when you talk about training "benefits" or "effectiveness", you're probably better off work out in a comfortable condition--meaning, in the cooler condition instead of too hot.  This has always been Arthur Lydiard's argument to high altitude training; it MIGHT be better off if you train at sea-level at higher aerobic effort (=faster speed) than plod along at altitude.  That, of course, is not to say that high altitude training doesn't have any merrit--looking at the results, you just can't deny it.  But for some people--a lot of us--, it is probably better off to do a good solid workout than subjecting yourself under tougher condition to gain extra benefit; probably because you ain't in a bigger scheme of things.

                              I'll be in Dallas next week.  Gonna run 50k around a park.  At least that will be at night.

                               

                              Fort Worth, right?  El Scorcho.  Buddy ran it a couple years ago.  I haven't yet.  Enjoy.

                              2014 Goals:

                              #1: Do what I can do. <DOING>

                              #2: 365 Hours training <NOPE, INJURED>

                               

                              xor


                                Yes, it will be my 3rd El Scorcho out of 5.  I was running them in even years (Dos and Cuatro), but I need to come visit my folks, so Cinco got me too.

                                 

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