Most triathletes are well aware that racing, and even training for, Ironman and Ironman 70.3 events does a number on the body and the mind. Training for a long-distance triathlon event that takes 4-7 hours (Ironman 70.3) or 8-17 hours (Ironman) is mentally and physically demanding. It takes careful planning and consideration of training intensity and training volume to manage the amount of stress and strain that an athlete experiences, otherwise the athlete can find themselves in a state of burnout or injury. The mental toll that heavy training loads take on athletes preparing for Ironman and Ironman 70.3 racing should also be considered. Some age group athletes will train 10-20 hours per week to prepare for these events, with professionals training upwards of 30-40 hours per week. The sheer volume of training will inevitably start to have a psychological impact. It is for these reasons above that a periodized approach to training is important in helping athletes prepare appropriately, maximize performance, and minimize any possible risk of poor outcomes.
In general, moderate and relatively short duration exercise (e.g., a 30-minute brisk walk) is good for us immediately afterwards and in the long-term. However, when exercise starts to become more extreme (e.g., a 4-hour bike ride with some intervals mixed into the middle of it), the immediate impacts that the body experiences after the session begin to change. In some studies, there have been immediate deleterious impacts noted in the body’s inflammatory balance and immune system balance (1, 2). In other words, the more extreme the exercise, the more of a toll the body takes and the more it shows up immediately after the session.
It does make some intuitive sense, however, as in order to see long-term positive adaptations, the body needs to be stressed in a way that it is not accustomed to followed by a period of recovery. Gentle and moderate exercise is not enough of a stress to improve athletic performance and it is likely not significant enough to throw our body’s internal environment out of homeostatic balance either. However, the type of training that most triathletes engage in certainly can throw things out of balance for a bit. A very tangible example of this is delayed onset muscle soreness that an athlete might experience after a hard run session or a heavy gym session. There are multiple reasons why delayed onset muscle soreness occurs, including potential micro-tearing of the muscle fibers to a pro-inflammatory response from damage incurred during the training session itself. However, the short-term damage and degradation ultimately, with the proper recovery, leads to the body bouncing back stronger and fitter than it was before. This is a concept known as supercompensation, and is essentially training in a nutshell: break the body down a bit, let it recover properly, break it down a bit more, let it recover again, and then show up to race fitter (i.e., capable of a higher exercise output) than you were previously.
However, what athletes and coaches sometimes might forget is just how stressful the actual event/race itself is on the body. While training is stressful too, usually athletes perform at a capacity and output that they don’t usually achieve in training. We rarely push our bodies to the absolute limit in any single training session, but race day is where athletes usually get close to that limit. So, what happens when athletes race a long-distance triathlon like an Ironman or an Ironman 70.3 event?
Acute Effects of Ironman & Ironman 70.3 Racing
An interesting 2020 paper published by Mrakic-Sposta and colleagues (1) describes the acute effects of Ironman and Ironman 70.3 racing on oxidative and inflammatory stress experienced by athletes. Essentially, the researchers in this study measured markers of oxidative stress and markers of inflammation before and immediately after 13 Ironman 70.3 athletes (age ~ 43 years) and 19 Ironman athletes (age ~42 years) competed in a single-day triathlon event.
The findings were not necessarily too surprising as markers of oxidative stress and markers of inflammation increased after participants completed their race. Oxidative stress, as measured by reactive oxygen species (ROS) in the body, increases as exercise intensity and duration is greater and greater. High levels of ROS can cause damage to other cells and can signal an immune response that creates a more pro-inflammatory environment. Hence, it is not all too surprising that there were signs of greater oxidative stress and greater inflammation after athletes finished either an Ironman or Ironman 70.3 event as they performed a large volume of exercise at a relatively high intensity (i.e., it was a race).
However, a few interesting additional findings were that oxidative stress was greater in older athletes, greater in those that trained more days/week in the final 2 weeks leading into race day, and inflammation as measured with the biomarker interleukin-6 (IL-6) was inversely correlated with the number of hours/week that an athlete trained in the last 2 weeks leading up to race day (i.e., IL-6 was lower in those that trained more in the last 2 weeks leading up to race day). However, all of these correlations were relatively small, albeit statistically significant.
So, what can we take away from this 2020 study discussed above? Well, it confirms what we already sort of suspected, that a single-day ultra-endurance event like an Ironman and Ironman 70.3 event poses a significant stress on the body’s internal environment. This study in particular looked at markers of immune function, oxidative stress, and inflammation. To no surprise, oxidative stress and inflammation was elevated in athletes immediately post-race. However, there were likely further damage or homeostatic imbalances incurred by the athletes that was not necessarily measured or captured in this study, such as muscular damage, dehydration, etc.
One takeaway from this study is as follows: The necessity for full and proper recovery after a very strenuous race such as an Ironman or Ironman 70.3 event should not be taken lightly. The good news is that all of the markers or signs of “damage” in athletes after a race like an Ironman or Ironman 70.3 will likely disappear within a few days or weeks and the body will return to its normal homeostatic balance with the proper amount of recovery. There is little or no research that follows triathletes long-term throughout training and racing to see what happens internally over weeks, months, and years; but in general, with the research we have, we know that there does not seem to be any evidence to indicate that a single-day event nor chronic endurance training poses any significant health risk (2). However, recovery should be a priority after a strenuous race, and the amount of time needed to recover should be respected as over-exerting, whether through racing too often or training too hard too often, can eventually lead to the body breaking down and being in a state of burnout or injury.
So, while training and racing for long-distance triathletes is ultimately a positive stress, it is indeed still a stress, and even too much of a good stress can eventually become a negative one. So, to stay healthy and to minimize the risk of overuse injury, all athletes should prioritize recovery and respect the level of stress that the body experiences in particular from long-distance races like Ironman and Ironman 70.3 events. In general, it is usually better to be a little conservative and to recover more than you think you need to after a race than it is to be too aggressive in returning to intense training or racing.
1. Mrakic-Sposta S, Gussoni M, Vezzoli A, Dellanoce C, Comassi M, Giardini G, Bruno RM, Montorsi M, Corciu A, Greco F, Pratali L. Acute effects of triathlon race on oxidative stress biomarkers. Oxidative medicine and cellular longevity. 2020 Jan 17.
2. Vleck V, Millet GP, Alves FB. The impact of triathlon training and racing on athletes’ general health. Sports Medicine. 2014 Dec;44(12):1659-92.
Happy training and racing!
-Ryan Eckert, MS, CSCS
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