The main finding of this investigation was that anthropometry and training volume were differentially correlated to total race time in both male and female Ironman triathletes, and that percent body fat was not associated with training volume for both genders. This cross-sectional study is limited regarding the influence and effects of anthropometry and both volume and intensity in training on race performance in Ironman triathletes, because only an intervention trial can answer this question. Other limitations are lack of fitness evaluation and experience of these athletes. The crude mean (SE) difference in race performance between the sexes was 65 (25) minutes, corresponding to a large effect size of 0.82 (Cohen's d). Effect size calculations for the bivariate associations between race performance and body fat in men and race performance and training volume in women were both >0.8 and have to be considered as large.
It seems from our results that male Ironman triathletes are very similar to runners from an anthropometric point of view. Our Ironman triathletes seemed to profit from a low percent body fat, which seemed also to enable a faster total race time (Figure 1). A relationship of this anthropometric variable with performance has already been found in runners over middle distances up to the marathon. Regional and total body fat correlated inversely with performance in an incremental treadmill exercise test in runners (10). Mattila et al. (21) found that fat percentage is significantly associated with 12-minute running performance. Elite runners over 10 km (2) and the marathon distance (3) also had low skin-fold values and low body fat. In addition, low body mass was advantageous in ultrarunners (11), and a low BMI was associated with race performance in female marathon runners (8). However, in our male and female triathletes, neither body mass nor BMI was correlated with total race time. The reason must be the higher BMI, because BMI in our triathletes was higher when compared with that of the male (11) and female (3) runners.
A further question is whether training volume might be of importance regarding race performance in Ironman triathletes. The training of our athletes is summarized in Table 2. We found no association of training volume with total race time for the male athletes (Figure 2). This study has examined a rather small sample of recreational male (n = 27) and female (n = 16) Ironman triathletes. Our male athletes finished the race within 11.25:22.0 (1.25:17.4) hours: minutes, the female athletes in 12.12:34.0 (1.5:19.2) hours: minutes. Elite male Ironman triathletes complete the distance in 8:30 to 9:00 hours: minutes, depending on the environment and the course. One might anticipate that a study of a larger cohort that included elite, and recreational, triathletes would show that training parameters do, in fact, influence race performance. The small sample size of our study might be a weakness in showing that training parameters effectively show an influence on race performance. According to O'Toole (22) and Gulbin and Gaffney (7), training distances appear to be a more important factor for competitive success than training paces. This is supported by the findings of Hendy and Boyer (9). According to their investigation, specificity in the relationship between training and performance appears to be supported especially by sports that rely more on the body such as swimming and running, and less on equipment such as cycling. In our male Ironman triathletes, neither average weekly training volume in hours nor in kilometers showed an association with race performance. Furthermore, the lower fitness level of recreational athletes compared when professional athletes might have influenced the findings.
However, in our female Ironman triathletes, training volume was significantly associated with total race time (Figure 5) in contrast to anthropometry (Figure 4). This is in agreement with previous findings in female triathletes. Leake and Carter (16) compared body composition in swimmers, triathletes, and runners. They found no correlates of anthropometry with the prediction of performance, and their conclusion was that training parameters were more important than anthropometric measures in female triathletes. All training variables (training distance in kilometers, training time in hours and training experience in years) were significantly correlated with race performance in their female short-distance triathletes. We must suggest after confirmation of their data that gender-specific differences seem to exist regarding the association of anthropometry and training in triathletes.
This investigation is limited because of the rather small sample size. Regarding the total field of finishers in the race, our male subjects represent 1.2% of all male finishers; our female subjects represent 9.9% out of all female finishers. The distribution of the race time of the male subjects represents the field of male athletes; however, the female subjects represent rather the back of the field. This cross-sectional study is limited regarding the influence and effects of anthropometry and both volume and intensity during training on race performance in Ironman triathletes, because only an intervention trial can answer this question. Other factors that could hypothetically influence performance include nutritional components, matching fluid losses with intake, biomechanics, relative training intensities, both mental and motivational considerations, etc., may also influence performance. These factors were not included in this observational study. Although the limitations are many, in this sample of triathletes, we found the mentioned relationships between anthropometrics and performance. We believe that the observed effect sizes together with the results of the multiple regression models strengthen our conclusion although based on observational findings.
We found in male nonprofessional Ironman triathletes that anthropometry in contrast to training volume was associated with total race time. In contrast, in female Ironman triathletes, training volume was related to total race time and not to anthropometry. We presume for male Ironman triathletes that anthropometry has a major association with race performance rather than training volume, and that male Ironman triathletes are very close to runners from the anthropometric point of view. The rather small sample size of this study might have influenced the outcome. Because percent body fat and average weekly training volume are not related for both male and female Ironman athletes, presumably the relationship between percent body fat, training volume, and race performance is genetically determined. When percent body fat and training volume show no relationship for both men and women, potential intensity in training could be associated with body fat. This might also explain why male athletes with lower body fat compete faster, and percent body fat is related to split times in swimming, cycling, and running in males, but not in females. However, the rather high BMI of these athletes compared with competitive runners might indicate that these recreational athletes were not training as intensely as professional triathletes do. In future studies, the relationship between anthropometry, training volume, and race performance should be investigated in a larger group of male and female Ironman triathletes, including professional triathletes.
For their help in translation, we thank Matthias Knechtle, Lausanne, Switzerland, and Mary Miller from Stockton-on-Tees, Cleveland in England, crew member of an ultraendurance support crew.
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