Triathlon training: yes or no to wetsuits in the pool?

One of the golden principles of training is specificity. In short, this means your training should be as specific as possible for the demands of your competitive event. A lot of the time, this is glaringly obvious; you wouldn’t train for a marathon by cycling, or train for a 400m freestyle event in the pool by performing backstroke sessions in the sea!

However, the specificity principle goes a lot deeper than this. For example, if you are training for a hilly or mountain marathon, you need to perform a chunk of training on the hills or in the mountains. Likewise, if you’re training for an open-water 400m freestyle race, you need to ensure your training includes open water sessions in order to learn how to cope with colder, choppy waters, where there are no lane lines to guide you and the psychology of knowing that the inky dark water below you can be very deep and shared with many other creatures!

Triathlon swimming

One of the main challenges and/or appeals of triathlon competition is competing in open water, where simply being a good swimmer in the pool is not enough – for all the reason given above. Physiologically, the biggest of these challenges is cold water. Since water conducts heat away from the skin nearly 20 times more effectively than air, temperatures that are absolutely fine for terrestrial training can cause major problems when the body is immersed in water. For example, running outdoors in cool/cold conditions of 5C (41F) is near ideal for maximum marathon performance⁽¹⁾. However, when immersed in water at 5C, progressive heat loss occurs and hypothermia begins to set in.

The initial effects of hypothermia involve peripheral muscle cooling, which can impair physical performance, reducing dexterity in the hands and finger followed by the failure of more global movements such as those involved in swimming⁽²⁾. In fact, even before this point, maximum muscle power falls – by around 3% for every degree C reduction in muscle temperature⁽³⁾. Continued cold water immersion leads to a progressive reduction in deep body temperature, leading to symptoms of hypothermia, confusion, introversion and disorientation⁽⁴⁾. Within 90 minutes or so, death will inevitably occur (see figure 1).

Figure 1: Water temperature, hypothermia and survival*