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From Fellrnr.com, Running tips
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Training for a spring race requires extra caution as you will have been training through the winter and be unprepared for warm conditions. While a spring race may be cool, there is also a risk of conditions that are warm enough (above 40f) to impair performance (see [Impact of Heat on Marathon Performance] for more details). Heat acclimation training, sometimes called heat adaptation training, can prepare you for these warmer conditions. This type of training is also valuable if you are traveling to a warmer climate for a race, or if you are training in the cool part of the day for a race in the warmer times. In addition, heat acclimation can improve cold weather performance. One study<ref name="performance"/> showed that heat acclimation improved performance in the cold by 6% and by 8% in heat.
==Background==
Exercise becomes harder as the temperature rises, with 40 degrees Fahrenheit being close to optimal. Exercise in the heat causes blood vessels in the skin to expand to help with cooling. The demands of the extra blood for cooling creates added stress on the cardiovascular system<ref name="Caso"/>. The athlete’s athlete's body will also sweat to produce cooling; in dry conditions evaporation of sweat provides 98% of cooling and in humid conditions 80%<ref name="Caso"/>. The loss of fluids due to sweating can lead to dehydration that also impairs performance. The impact of dehydration is in addition to the impact of the heat<ref name="Caso"/>.
==Danger of Death==
A dedicated athlete can push themselves hard enough to raise their core temperature to dangerous levels, leading to heatstroke, which can be fatal<ref name="Binkley"/>. Heatstroke can be the result of prolonged exercise in hot conditions, but it can also be the '''result of shorter periods of high intensity exercise, especially in the untrained or overweight'''. It is vitally important that heat acclimation training is started gradually. You must become aware of how your body is adjusting to the heat, and to learn the warning signs of elevated core temperatures. Training in heat suits (see below) is especially dangerous, as the heat will not escape even after you collapse! Generally, an athlete reaches ‘voluntary exhaustion’ 'voluntary exhaustion' when their core temperature reaches about 39c/102f<ref name="Nielsen"/>, so never push hard with heat acclimation. I would take it as a personal favor if you could avoid killing yourself.
==Symptoms of Heat Stroke==
If you have any of the following symptoms while performing heat acclimation training, you should stop and cool off. Taking your internal temperature, ideally with an in-ear thermometer will allow you to double check if this is heat stroke. Heat stroke is caused by an internal temperature of >40.6 °C (105.1 °F), is extremely dangerous and can be fatal. The following can be symptoms of heat stroke:
* Like any new training routine, start off slowly and build up both duration and intensity over time.
* Be aware of how you are feeling and avoid pushing hard.
* Build up to exercising at 50% [[VO2max]] or above<ref name="Armstron1991Armstrong-1991"/>. 50% of [[VO2max]] is about 70% of maximum [[Heart Rate]]<ref name="swain"/> or "very slow running"<ref name="brianmac"/>.
* Use gradually increasing periods from 30 to 100 minutes over 10 to 14 days<ref name="Shapiro"/>
* Acclimation is fully developed after 7 to 14 days<ref name="Armstron1991Armstrong-1991"/>, but up to 75% of acclimation is reached after 5 days <ref name="Shapiro"/>.
* Reduce your training load to compensate for the added stress of the heat. The heat can make you far more tiered than you would expect.
* Consider alternating heat acclimation training and cooler training to preserve intensity<ref name="Noakes"/>
==Fellrnr Heat Suit==
This 'heat suit' will allow for heat training even in quite cool conditions. However, it works by preventing the body cooling itself, so it increases the risk of heat stroke. If you overheat wearing this heat suit, you will not cool off after you collapse. Please be careful taking this approach, and start off with very low intensity exercise.
The key to the Fellrnr Heat Suit comes from two waterproof layers. A traditional sweat suit uses a single waterproof layer to trap your sweat and preventing it from cooling your body. The problem with the single layer is that the sweat soaks through any clothing and reduces the insulation. In cooler conditions the sweat soaked clothes can become chilly even with the waterproof layer. The Fellrnr Heat Suit approach traps the sweat away from the insulation layer, preventing this cooling effect. The Fellrnr Heat Suit has the following layers over both your top and legs:
* A close fitting thermal layer near the skin. The purpose of this layer is to hold the sweat and keep your skin relatively comfortable.
* A waterproof layer that traps the sweat in the first thermal layer.
* An insulation layer, such as fleece that prevents any heat escaping. Because it is trapped between the two waterproof layers, it never becomes wet.
* A second waterproof or windproof layer that traps the body’s body's heat in the insulation layer.
* In addition, wear hat, gloves and ideally a neck warmer or face mask.
This combination will prevent the majority of heat escaping your body.
* The athlete becomes psychologically prepared for heat stress. <ref name="ismj"/>
* The ability to consume and absorb more fluids (anecdotal evidence only)
===Notes on Heat Acclimatization ===
* Younger runners do better in the heat than older runners but training can negate this<ref name="Armstron1991Armstrong-1991"/>* Acclimation is faster in fitter athletes<ref name="Armstron1991Armstrong-1991"/>* On return to a cool climate, acclimation lasts for about a week, then decays<ref name="Armstron1991Armstrong-1991"/>
* People who have always lived in hot climates are believed to have superior adaptation<ref name="Noakes"/>
==See Also==
* Running calculators
* [[Running in the Heat]]
* [[Impact of Heat on Marathon Performance]]
== references ==
<references>
<ref name="Armstron1991Armstrong-1991"> LE. Armstrong, CM. Maresh, The induction and decay of heat acclimatisation in trained athletes., Sports Med, volume 12, issue 5, pages 302-12, Nov 1991, PMID [http://www.ncbi.nlm.nih.gov/pubmed/1763248 The induction and decay of heat acclimatisation in trained athletes.1763248]</ref><ref name="Shapiro">https://www Y. Shapiro, D. Moran, Y.thiemeEpstein, Acclimatization strategies-connect-preparing for exercise in the heat.com, Int J Sports Med, volume 19 Suppl 2, pages S161-3, Jun 1998, doi [http:/ejournals/abstract/sportsmed/dx.doi.org/10.1055/s-2007-971986 Acclimatization Strategies 10.1055/s-2007- Preparing for Exercise in the Heat971986], PMID [http://www.ncbi.nlm.nih.gov/pubmed/9694427 9694427]</ref><ref name="Noakes">The Timothy Noakes, Lore of Runningrunning, date 2003, publisher Human Kinetics, location Champaign, Tim NoakesIL, isbn 0-87322-959-2, pp pages 188</ref><ref name="Noakes2">The Timothy Noakes, Lore of Runningrunning, Tim Noakesdate 2003, publisher Human Kinetics, location Champaign, IL, isbn 0-87322-959-2, pp pages 214</ref><ref name="Caso"> DJ. Casa, Exercise in the heat. I. Fundamentals of thermal physiology, performance implications, and dehydration., J Athl Train, volume 34, issue 3, pages 246-52, Jul 1999, PMID [http://www.ncbi.nlm.nih.gov/pmcpubmed/articles/PMC1322918/pdf/jathtrain00007-0030.pdf Exercise in the Heat. I. Fundamentals of Thermal Physiology, Performance Implications, and Dehydration16558572 16558572]</ref><ref name="Nielsen">http://wwwB. Nielsen, JR. Hales, S.ncbiStrange, NJ.nlmChristensen, J.nihWarberg, B.gov/pmc/articles/PMC1175224/ Saltin, Human circulatory and thermoregulatory adaptations with heat acclimation and exercise in a hot, dry environment., J Physiol, volume 460, pages 467-85, Jan 1993, PMID [http://www.ncbi.nlm.nih.gov/pubmed/8487204 8487204]</ref><ref name="Binkley">HM. Binkley, J. Beckett, DJ. Casa, DM. Kleiner, PE. Plummer, National Athletic Trainers' Association Position Statement: Exertional Heat Illnesses., J Athl Train, volume 37, issue 3, pages 329-343, Sep 2002, PMID [http://www.ncbi.nlm.nih.gov/pmc/articlespubmed/PMC164365/ National Athletic Trainers' Association Position Statement: Exertional Heat Illnesses12937591 12937591]</ref><ref name="ismj">httpTaylor, Nigel AS, and James D. Cotter. "Heat adaptation: guidelines for the optimisation of human performance://wwwreview article.ismj" International SportMed Journal: The Extreme Environment and Sports Medicine: Part 2 7.com/default.asp?pageID=854255817%20-%2029/03/1 (2006%20): p-%20Rank:033.</ref><ref name="swain">DP. Swain et al (1994) ', KS. Abernathy, CS. Smith, SJ. Lee, SA. Bunn, Target HR heart rates for the development of CV cardiorespiratory fitness' - Medicine & Science in ., Med Sci Sports & ExerciseExerc, volume 26(, issue 1), pages 112-1166, Jan 1994, PMID [http://www.ncbi.nlm.nih.gov/pubmed/8133731 8133731]</ref>
<ref name="brianmac">http://www.brianmac.co.uk/vo2max.htm</ref>
<ref name="postsauna">GS. Scoon, WG. Hopkins, S. Mayhew, JD. Cotter, Effect of post-exercise sauna bathing on the endurance performance of competitive male runners ., J Sci Med Sport, volume 10, issue 4, pages 259-62, Aug 2007, doi [http://wwwdx.doi.org/10.1016/j.jsams.2006.06.009 10.1016/j.jsams.org2006.06.009], PMID [http:/article/S1440-2440%2806%2900139-3www.ncbi.nlm.nih.gov/pubmed/abstract16877041 16877041]</ref><ref name="performance">S. Lorenzo, JR. Halliwill, MN. Sawka, CT. Minson, Heat acclimation improves exercise performance ., J Appl Physiol (1985), volume 109, issue 4, pages 1140-7, Oct 2010, doi [http://dx.doi.org/10.1152/japplphysiol.00495.2010 10.1152/japplphysiol.00495.2010], PMID [http://www.ncbi.nlm.nih.gov/pubmed/20724560 20724560]</ref>
</references>
