Abstract
This study aimed to determine the effects of consuming a high fat solution (HFS) compared to a high carbohydrate solution (HCS) during a cycling effort on substrate oxidation, muscle oxygenation and performance with cyclists and triathletes. Thirteen men participated in this study (age: 30.4 ± 6.3 y; height: 178.7 ± 6.1 cm; weight: 74.9 ± 6.5 kg; V̇O2 peak: 60.5 ± 7.9 mlO2×kg-1×min-1). The solutions were isocaloric (total of 720 kcal) and were consumed every 20 minutes. Each solution of HFS contained 12.78 g of lipids, 1.33 g of carbohydrates and 0.67 g of proteins, and each solution of HCS contained 28 g of carbohydrates. We measured pulmonary oxygen consumption and skeletal muscle oxygenation, using a Near Infrared Spectrometer (NIRS) during a cycling effort consisting of 2 hours at 65 % of maximal aerobic power (MAP) followed immediately by a 3-minute time-trial (TT). We observed that the consumption of the HFS increased the rate of fat oxidation at the end of the sub-maximal effort (0.61 ± 0.14 vs 0.53 ± 0.17 g×min-1, p < 0.05). We have also shown that the HFS negatively affected the performance in the TT (mean Watts: HCS: 347.0 ± 77.4 vs HFS: 326.5 ± 88.8 W; p < 0.05) and the rating of perceived exertions during the sub-maximal effort (modified Borg Perceived Exertion scale: 1–10) (mean: 3.62 ± 0.58 for HCS vs 4.16 ± 0.62 for HFS; p < 0.05). We did not observe a significant effect of the acute consumption of the HFS compared to the HCS on muscle oxygenation during the cycling effort. Finally, we observed that cyclists who demonstrated a high skeletal muscle deoxygenation relative to their pulmonary oxygen consumption (DHHb/V̇O2) had a higher fat oxidation capacity (higher Fatmax). In conclusion, even though the consumption of HFS increased the rate of fat oxidation at the end of a sub-maximal effort, it did not affect muscle oxygenation and it negatively affected performance and perceived exertion during a time-trial and caused gastro-intestinal distress in some participants.
 Keywords: Fat oxidation, Skeletal muscle oxygenation, Lipid supplementation, Carbohydrate supplementation, Near Infrared Spectroscopy (NIRS), Cycling, Triathlon.
Highlights
BackgroundLong distance triathlons and cycling competitions are gaining in popularity (Hadzipetros, 2009; Smale, 2016) and athletes are looking for ways to improve their performance, whether it is with a better-structured training plan, better equipment or by improving their nutrition
We hypothesized that the deoxyhemoglobin (HHb) would be higher during the SE when the participants consume the high fat solution since more oxygen would be used in the muscles, due to a higher fat oxidation rate, but we did not observe a significant effect of the acute consumption of the HFS compared to the high carbohydrate solution (HCS) on muscle oxygenation during the cycling effort
We demonstrated that the respiratory exchange ratio (RER) slope for both the HCS and the HFS conditions decreased in a significant manner during the SE and the RER slope for HFS decreased more steeply, which shows a greater reliance on fat oxidation for energy (Miura et al, 2000)
Summary
BackgroundLong distance triathlons and cycling competitions are gaining in popularity (Hadzipetros, 2009; Smale, 2016) and athletes are looking for ways to improve their performance, whether it is with a better-structured training plan, better equipment or by improving their nutrition. Due to the duration and intensity of these events, fueling properly is a big challenge for the athletes. A good fat oxidation capacity, combined with carbohydrate intake during endurance events, would allow an athlete to preserve more glycogen which can be used when the intensity increases, such as when a cyclist needs to respond to an acceleration or at the end of the race when the athletes are accelerating toward the finish line (Hall et al, 2016; Jeukendrup & Achten, 2001). Endurance athletes generally have a good fat oxidation capacity, but there are many ways an athlete can increase even more their fat oxidation capacity, such as doing long aerobic training, doing fasted training, training twice a day or by training with minimum or without carbohydrate intake (Hawley, 2014)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
