Peak Fat Oxidation is not Independently Related to Ironman Performance in Women

Abstract

The aim of the present study was to investigate if peak fat oxidation rate (PFO) is related to Ironman performance in female athletes. Thirty-six female Ironman athletes (age: 34±1 yrs, [21-45 yrs.] SEM [Range]) with a BMI of 22.1±2.0 kg/m [18.8-28.4 kg/m], a body fat percentage of 24.8±1.0% [9.0-37.0%] and a V̇Opeak of 53.0±1.3 ml/min/kg [36.5-70.5 ml/min/kg] were tested in the laboratory prior to the Ironman Copenhagen 2017. Race time ranged from 9:17:07 to 15:23:48 with mean race time being 11:57:26 h:min:s (717 min). By simple linear regression analyses we found associations between race time and P FO (r=0.22, p<0.005), V̇Opeak (r=0.65, p<0.0001) and the relative exercise intensity eliciting PFO (Fatmax) (r=0.35, p=0.0001). Furthermore, associations were found between race time and body fat percentage (r=0.44, p<0.0001) and age (r=0.16, p<0.05). By means of multiple regression analysis, V̇Opeak was the only statistically significant variable explaining 64% of the variation in race time (adj. r=0.64, p<0.005). In conclusion, these results demonstrate that PFO is not independently related to Ironman performance in a heterogeneous group of female athletes. Interestingly, V̇Opeak alone was able to predict 64% of the variation in Ironman race times.

The relationship between peak fat oxidation and prolonged double‐poling endurance exercise performance

“…Overall, the values of PFO and Fat max in the present study are very comparable to values reported in ironman triathletes. 11,12 Likewise, the values of RS and ES are similar to those of recreationally active males and of endurance-trained males, as well as CC-skiers, respectively. 43,44 Whole-body fat oxidation rates during exercise have previously been proposed to be closely tied to resting plasma FFA concentrations in male athletes.…”

“…10 Recently, the relationship between prolonged endurance performance and the peak fat oxidation rate (PFO) was investigated in male and female ironman triathletes. 11,12 PFO was measured during a graded exercise protocol, and race time in the Copenhagen Ironman was used as measure of performance. PFO 11,12 and the exercise intensity at which it occurs (Fat max ) 12 were negatively correlated with race time, albeit V O 2peak was the strongest predictor of performance.…”

“…11,12 PFO was measured during a graded exercise protocol, and race time in the Copenhagen Ironman was used as measure of performance. PFO 11,12 and the exercise intensity at which it occurs (Fat max ) 12 were negatively correlated with race time, albeit V O 2peak was the strongest predictor of performance. 11,12 Together, these results suggest that PFO and Fat max are related to prolonged endurance performance, thus indicating a potential performance benefit in athletes with superior fat oxidation.…”

Ultra Trail Performance is Differently Predicted by Endurance Variables in Men and Women

“…This has sparked interest into strategies to augment fat oxidation during endurance exercise to preserve endogenous carbohydrate stores [15,17]. Yet, no previous research regarding trail running performance factors have examined whether fat metabolism keeps a significant relationship with race time, as it has been demonstrated for Ironman triathlon [16,18].…”

“…Lastly, we were interested in exploring possible associations between body composition and race time. Our hypothesis were: (1) peak oxygen uptake, peak speed and speed at first and second ventilatory thresholds would be related with performance; (2) maximal fat oxidation capacity would be independently associated with performance in male but not in female athletes [16,18].…”