Science Examines Source of Fatigue in Triathletes

Science says triathlons are tiring. Well, duh. But now they know WHY they are so tiring, specifically, and give us some ideas on how to strategize for better performance.

It seems like common sense that completing a triathlon is tiring, right? But what exactly is happening that makes you tired? And is there anything you can do about it? Well, scientists took a closer look: a study was recently conducted on 25 trained triathletes to investigate the cause of muscle fatigue experienced during a half-Ironman distance triathlon. The triathlon is an endurance sport that combines phases of swimming, cycling, and running, and while the Ironman distance is the most infamous, shorter races such as the Olympic or half-Ironman have become popular since they are more manageable to amateur and recreational athletes.

There were 31 triathletes who volunteered to participate in the study, but 6 were excluded since they failed to complete the triathlon race. All participants had previous experience of at least three years and had trained for about 2 hours per day, 4-5 days a week during the previous year. The participants had also completed at least one prior triathlon in the half-Ironman distance.1

The participants underwent a physical exam one to three days prior to the race. Pre-exercise variables were assessed 60-90 minutes before the race. The variables measured included urine specific gravity, body fat composition, pre-race body water content, and a blood sample was taken. Each participant completed a 10 minute warm-up that consisted of dynamic exercises and practice jumps. Following the warm-up, participants performed 2 countermovement vertical jumps to determine their max height. Max handgrip force was also measured in both hands.2

The race consisted of 1.9 kilometers of swimming, 75 kilometers of cycling, and 21.1 kilometers of running. Within 3 minutes of the end of the race, subjects went to an area to perform two countermovement vertical jumps. Body weight and body water content were recorded again, and another blood sample was obtained. After hydration and 30-60 minutes after race completion, another urine sample was taken. The dehydration level and water content was calculated by using both urine samples.3

The results of the data from the study showed that jump height and leg power output were significantly reduced after the race. Handgrip force was not affected. The average dehydration after the race was higher, but varied upon the individual. Blood myoglobin and creatine kinase concentration increased after the race, indicating muscle damage.4

The researchers concluded that during a half-iron distance triathlon the ability of the leg muscles to produce force is diminished as a result of muscle damage. Hydration and blood glucose concentration, previously thought to play a major role in fatigue, turned out to be relatively minor factors due to the athletes’ hydration and feeding strategies already in place. As such, athletes wishing to increase performance should look to techniques to decrease leg muscle damage as a way to decrease fatigue.

Photo courtesy of Shutterstock.

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