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Hot Weather Training or How to Go Fast in the Heat and Live to Brag About It

Triathlon is a sport traditionally raced in the late spring, summer, and early fall. Our winter races are usually in the tropics or southern hemisphere, where it is summer. Also, triathlon race directors will routinely start races in temperature and humidity conditions that would result in the cancellation of a marathon due to perceived extreme risk of heat injury to the competitors and the resultant liability risks.

So, if you are going to do a race that can be warm or even hot, the questions are how best to prepare yourself to race in the heat and how to recognize the early signs of heat related injury so you don't become a casualty instead of a competitor. Intensive preparation including acclimatizing yourself to the conditions, and an exacting attention to fluid and salt requirements can also allow you to use your race preparation as an offensive competitive tool to help you win.

The down side is that failure to listen to your body very carefully while racing and training in the heat, can lead to severe lasting injury and even death in the worse case scenario.

The Physiology of Heat and Exercise

When experts examine weather conditions for competitive endurance events, heat begins to be a risk factor well below 80° F, especially if the humidity is over 70%. Then as the temperature and humidity rise to, and above, these levels, the air progressively hinders your body's ability to dissipate the heat that is generated by your body's rapid conversion of energy into forward motion. Triathlons shorter than Olympic distance are not much of a problem as hyperthermia (overheating) is usually only an issue on the run. Since it takes 10+ minutes for the body to begin to heat up while running, the short runs in sprint races are rarely an issue for the competitors.

Cycling in the heat rarely leads to hyperthermia during training or racing because of excellent heat loss through evaporation due to high air flow velocities. One exception to this rule occurs in extreme environments. For example, in the St. Croix 70.3 Triathlon, the temperature can be 90+ degrees, with humidity >90%.  On downwind sections of the course if the athlete is cycling at 20 mph and the wind is blowing at 20 mph, there is a net air flow velocity of zero. Then hyperthermia becomes an issue on the bike.

Normally you lose heat by radiation, convection, and evaporation. Evaporation of water from your skin and your lungs as you breathe is the most important mechanism for controlling the rise in body temperature that will occur when heat production from exercise exceeds heat loss  to the surrounding air. This becomes an issue if your body temperature rises to 102-103°, and a progressive danger as that temperature rises past 104°. Body temperatures over 105°expose you to risks of injury and death. Remember that before heat stroke occurs, you can drastically reduce heat production by just stopping. Past a certain poorly- defined point in the process of heat injury, however, active cooling is needed to prevent injury. 

The complex relationship between heat and humidity and the risk of injury have led to the development of combined measures such as the Heat Index. This is illustrated in the following link:

http://www.nsis.org/weather/heatindex.html

Larger individuals have more potential risk for heat-related problems as they have less surface area per pound of body mass, and more muscle mass per square foot of surface area. The insulation provided by body fat is also a risk factor as it prevents heat loss in an efficient manner.

Another factor to consider is that hot, very dry environments lead to very rapid evaporation of water from your skin ( Ironman Arizona, and the Grand Columbian are good examples.) This beneficially increases heat loss from evaporation, so wetting yourself can improve heat loss. The downsides are that you lose more fluid from sweating and the rapid evaporation can delude you into a lower perceived fluid loss rate and lead you to ingest less fluid and salt replacement.

Lastly, data from large sources such as the US military strongly suggest that occurrence of heat exhaustion or heat stroke then predisposes the individual to recurrent episodes of the same problem. So you must go to great lengths to avoid these dangerous problems. If you have had a prior heat stroke, my advice to you is to avoid hot weather training and races entirely.

Types of heat illness and their treatment

Heat Cramps:

Symptoms: muscle cramps, usually in the legs, and occurring after prolonged exertion

Treatment: slow down; increase fluid and salt intake to your limit of tolerance; if necessary, walk or seek refuge in the shade. These cramps will often abate with treatment and time so you can then resume training or racing after as little as 10-15 minutes.

Heat Exhaustion:

Symptoms:  headache, nausea, dizziness, cool and clammy skin, pale face, cramps, weakness, profuse perspiration, mild disorientation but no true confusion.

Treatment: STOP racing or training; get in the shade; drink cool or cold salt containing fluids; get assistance if you do not rapidly improve within minutes. Immersion in water may help. You are done racing/training for that day!

Heat Stroke:

Symptoms: headache, disorientation, nausea, face flushed, hot and dry skin, no perspiration, body temperature over 101°F, chills, rapid pulse. Unfortunately, endurance athletes can suffer heat stroke occasionally without having a warning period before sweating stops.

Treatment:  cool the person immediately; move to shade or indoors; wrap in a cool, wet sheet; get medical assistance ASAP.  Partial immersion in water can be lifesaving if medical help is not available. This is what the course volunteers or bystanders should do for you. If you are a careful observer of your body and feelings and you feel any of the symptoms described above, you should immediately take action. Particularly, if you were to stop sweating and/or develop "goose bumps", and/or suddenly feel cold, you must stop immediately and take action to lower your body temperature.

Strategies for hot weather training and racing:

1. You can clearly acclimatize yourself to exercise in the heat.
Acclimatization involves slowly increasing the intensity and duration of aerobic cycling and running in hot conditions over several weeks. A wise procedure would be to schedule base pace workouts in the heat initially every 2-3 days. Your body will respond by increasing your sweat rate significantly. Recognize that workouts in the heat will mean that you need more rest afterward AND significantly more salt and fluid. In very long workouts you simply cannot carry enough liquid with you and the only solution is to either stash a refill along the route or carry cash and plan your route to pass places you can stop to buy more electrolyte replacement drinks.

2.Fluid and salt replacement are the keys to success in hot weather training and racing.
The best strategy for getting your salt and fluids right is to weigh yourself naked before and, as soon as possible, after workouts. Other methods are either expensive, impractical, or both. Chart these weights and progressively increase your fluid and salt intake until you lose less than a 1/2 pound for workouts less than about 3 hours and a max of a pound for longer ones. Remember that dehydration is a major risk factor in the occurrence of heat exhaustion and heat stroke. Very few athletes can ingest more than 250-300 Kcal per hour at race pace, but most can train themselves to drink up to 32 oz or more per hour. The article referenced below addresses this issue. Read the article

3.Water/ice are not for drinking, but for cooling yourself.
Excessive water consumption is such a problem with Ironman athletes that the Association of Ironman Medical directors has recommended that water not be even offered at every aid stop. Since you are sweating salt water, and breathing out pure water, replacement should be a salt and water solution containing both sodium and potassium salts at a concentration somewhat less than the salt concentration in your blood. Drinking much water can lead to progressive hyponatremia. In the worst possible case that can lead to cerebral edema and death. In the best case it will reduce your performance.

4. Wear a white or light colored hat while running.
A light or white hat, especially if the underside of the brim is dark, can significantly reduce head and face temperatures in the sun by 10-15 °. Hats also form a convenient ice holder that will cool you and the water from the melting ice can wet your head and clothing to increase evaporative heat loss.

5. Don't warm up for races in extreme conditions.
Your body temperature is a balancing act between heat gain and loss. Warming up (except for the swim in a non wetsuit race means you start the race with a higher body temperature. Some elite athletes actually use cooling vests to reduce body temperatures immediately prior to a race. Cooling vest information is found at the link below.
http://www.arcticheatusa.com/

6. If you get muscle cramps then you need more salt.
Added salt intake can be a major factor in reducing cramping and must include both potassium and sodium salts. Try to either train yourself to race on the replacement fluid offered by your race organizer (which usually means you need another source of salt) or be prepared to provide at least some of your own fluid needs. For instance, in a 1/2 IM race you could start the bike with 2-3 20 oz bottles on your bike and start your run with a bottle in a carrier. Since you may need up to 200 oz of fluid to race a race of 5 1/2 to 6 hrs in extreme conditions with optimal hydration, you would be carrying at least 60-80 oz of your preferred drink mix. You still must try the race-provided drink during your training. It is unwise to drink anything during a race that you haven't used in your longer brick workouts.
My own personal requirement is 1/2 Cytomax -1/2 Accelerade with a minimum of 1/8 tsp table salt per 20 oz bottle. The salt content is raised with the temperature to 1/2 tsp at about 90°+ F. I also carry and use 2-4 proprietary salt tablets beginningabout 2 hours into a race or training workout.

7. Different folks sweat different amounts of salt.
Salt content of sweat varies widely from person to person, so there is no inexpensive or practical substitute for experimentation on yourself to determine your needs. In the heat remember to add salt until you stop cramping on longer workouts that contain at least some elements approaching AT (Anaerobic Threshold.)

8. Dampening yourself with water can dramatically increase your heat loss in certain conditions
On the bike, picking up a water bottle and spraying some on your back while riding every 10-15 minutes can increase your evaporative heat loss. Likewise, while running you can drizzle ice water from water stops over your torso and head to increase evaporative losses. Beware, however, that too much water so as to flood your shoes and wet your feet is a sure recipe for blisters that could end your race before the finish line.

9. Blisters on your feet and abrasion injury to various parts of your anatomy are a real problem in hot weather.
There are sure-fire strategies to help out here. Lubricants applied to underarms, nipples, and crotch areas are very helpful. Trying to keep your feet relatively dry always helps. Lubricants, either dry (talcum powder) or wet (Body Glide/Sport Slick) can reduce friction and blistering in both bike and running shoes. Toughening your feet can also help. Two ways to do this include conditioning your feet to do without socks slowly over months; and to paint the susceptible areas of your feet daily with Tincture of Iodine (TOI ) from the beginning of training season. TOI is well tolerated unless you are allergic to iodine. Also, it dries in 2-3 minutes so you can then walk around without staining the floor coverings or your bed sheets. (I go up to 1/2 IM without socks and virtually never blister using this process. My socks come off when the snow melts.)
Toughening your feet also contributes to pro-style transition times (the 4th sport in triathlon) as you save 10-30+ seconds by not donning socks. Lastly, in salt water swims, always rinse with fresh water before jumping on your bike, even if you have to bring your own water in an old Gatorade bottle. Salt from the ocean will scrub you raw as it dries into crystals.

10. Last but not least, avoid sun damage to your skin.
Sunburn is very, very bad. Melanoma is a deadly disease, and every sunburn increases your chances of getting this dreadful cancer. Protect the one and only issue of skin you'll ever have by including the following on your must do list: Buy training tops that are cool, readily aid in water evaporation, and that have protection for your neck and shoulders. Light colors or white helps keep you cool. Please remember that you can sunburn through very "see-through" fabrics.
Don't expect your suntan lotion to survive a swim with your wet suit. The fabric liner of the suit will remove most of the lotion from your skin. Remember to apply protective stuff to your face, ears, and nose. Never race with suntan lotion you haven't pre-tested during training to include swimming.
The best suntan lotions for daily use unfortunately are not sold in the US. The FDA hasn't approved the best chemical additives, but the Canadian government has done so. Brands sold through Canadian pharmacies such as L'Oreal's Ombrelle Extreme SPF-30 lotion are excellent and hypoallergenic. So get with a few friends and order by mail from Canada. The 240 ml bottles are economical.

In summary:  Hot weather training can dramatically improve your performance in hot weather racing. A couple of workouts per week at 2 pm, coupled with extra rest, can acclimate you to this extreme environment. Recognize that you must absolutely listen to your body, and that errors can exact a very high price. In extremely hot weather, only the smart, acclimated racers that can ride the line between performance and destruction survive to win. SO, If you want to be Jimmy Buffet's "last man standing" as the song says, practice in the heat if your "A" race is hot and listen very, very carefully to what your body has to say every  minute. Hydration, salt, prevention of sunburn, and body temperature control are the key issues.

My own personal experience in this area has led to numerous hot weather race wins against competitors I never thought I could begin to compete with on my best day. They DNF'd due to the heat and I paced and drank my way to a win on more than one day. My 2004 race win in St. Croix took approx 200 oz of fluid intake to win, and the bank thermometer read 99° on the last lap of the run.

Additional References and information:

http://sportsmedicine.about.com/cs/hydration/a/acsmfluid.htm

American College of Sports Medicine Position Stand. Heat and Cold Illnesses during Distance Running. Med Sci Sports Exerc 1996; 28:i-x.

Note that I depart from standardized recommendations about salt intake. Those standard recommendations assume we would not even be racing under the conditions that we commonly face as competitors in some hot race venues. Application of rules used in marathons would result in cancellation of numerous summer triathlons due to the temperature at race start time and/or the projected maximum temperature and humidity during the event.
   
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