Triathlon

Physiology of triathlon

Triathlons occur in a variety of distances, from the Sprint (750m swim, 20km bike, 5km run) and the Olympic (1.5km swim, 40km bike, 10km run)to the Half Ironman (1.2mile swim, 56mile bike, 13.1mile run) and Ironman (2.4mile swim, 102mile bike, 26.2mile run) Distance races. Each triathlon event and distance involves a variety of environmental and medical considerations.

Swimming Considerations

Probably the number one medical concern for the swim portion of a triathlon is the water temperature. Oftentimes, the water temperature makes wetsuits unnecessary, but triathlons will often allow their use even if the water is that warm. However, if race officials announce race morning that the water temperature is above the wetsuit-legal limit of 78 then participants will often not be eligible for an age group award if a wetsuit is worn. So if the water is above the limit of 78°, what is the benefit to wearing a wetsuit? The wetsuits are made of neoprene; in addition to providing some protection from the other swimmers’ arms, hands, legs and fingernails, neoprene is also a very buoyant material. The more an athlete floats, the less resistance is encountered, thereby making it that much easier to move through the water.

In addition to concerns about water temperature, acclimatization is important. Prior to competing in the swim, athletes should consider it essential to become familiar with the swim course. And to the best of their ability, the athletes should understand what it is like to swim in such a location and event. It will be difficult to mimic the chaos of swimming amongst hundreds of flailing arms and legs, but appreciating what it is like to swim in open water is quite helpful. Swimming in an open water environment is quite different from swimming in your local pool and can produce in some a quite anxious feeling. It is one thing to imagine swimming in open water amongst all the other athletes, it is quite another to actually do so. Therefore, if such an anxiety exists for you, desensitizing yourself to the environment (by gradually becoming more familiar with it) will do a world of good and will make the swim that much more enjoyable.

Cycling Considerations

Fluid replacement is one of the most important concerns during the cycling segment of triathlon. The fluids consumed during the triathlon perform multiple roles, perhaps the two most important are the replacement of water and electrolytes lost to sweating and (potentially) decreasing built up heat. The need to replace fluid is not controversial. What is, however, is the substance to replace it with, plain water or commercially-available electrolyte replacement drink. Hyponatremia following the race is a relatively recent issue. Hyponatremia is essentially too low levels of electrolytes thought to be due to a combination of electrolytes lost to sweating and excess water consumed. The current thought is that consuming the aforementioned electrolyte replacement fluids prevents hyponatremia. Further, and post-race hyponatremia concerns aside, there is also evidence that consuming a flavored electrolyte substance better maintains proper hydration status when compared to drinking unflavored (plain) water. It might be that drinking something flavored provided more fluids or consuming electrolytes prevented dehydration. Regardless, most organizations (like the American College of Sports Medicine, among others) now recommend electrolyte replacement beverages during endurance competitions.

Running Considerations

The same dehydration concerns during the cycling leg continue for the running segment. By this time, however, having been exposed to the sun and other elements for more than an hour causes an increase in internal temperature and excessive radiation exposure.

During the Hawaii Ironman triathlon, the amount of ultraviolet radiation (as measured by erythema doses) was significantly higher than those recommended by the International Radiation Protection Agency. During this study, each athlete was sunburned, though each of them had used sunscreen with an SPF greater than 25. A combination of adequate sunscreen and proper clothing can prevent some of these adverse effects.

Concerning the likely increase in internal temperature, the most common issues are heat illness. The conditions that both contribute to and exacerbate these illnesses include: obesity, low fitness levels, dehydration, history of heat illness, lack of acclimatization, sleep deprivation, sunburn and illness less than one week prior to the event. Appropriate training will address the first two concerns (obesity and fitness) while the previously discussed fluid replacement strategies cover the next (dehydration).

Wetsuits, electrolytes and sunscreen . . . so much more to the triathlon than simply swimming, biking and running. So as you prepare for a triathlon:

• Become familiar with the swim course and accustomed to swimming in open water (preferably amongst many other swimmers).
• Have a solid, practical fluid replacement strategy for both the bike and run portions of the triathlon. Doing so prevents a great many injuries and illnesses.
• Train, train, train. Like proper fluid replacement, the better fitness you have, the more “used to” each segment you are, the less likely you are to have adverse medical conditions during or afterward.

Groups we’ve worked with:

• Omaha Triathlon
• Omaha Women’s Triathlon
• Team Nebraska Triathlon