Energy and Macronutrient Metabolism in High Performance Athletes (Oral Session 20)

(OR20-01-25) Exogenous Carbohydrate Oxidation Is Higher Regardless of Energy Status When Glucose + Fructose Is Consumed During Endurance Exercise Compared to Glucose Alone

Tuesday, June 3, 2025

8:30 AM – 8:42 AM ET

Location: S230 CD

Emerging Leaders in Nutrition Science Poster Competition

Presenting Author(s)

David E. Barney, Jr., PhD

Postdoctoral Researcher
U.S. Army Research Institute of Environmental Medicine
Natick, Massachusetts, United States

Disclosure(s): No relevant financial relationship(s) with ineligible companies to disclose.

Co-Author(s)

KP

Kimberly N. Panik, MS, RD

Oak Ridge Institute of Environmental Science (ORISE) Fellow
U.S. Army Research Institute of Environmental Medicine
Boston, Massachusetts, United States
JM

Julia Michalak, BS

Oak Ridge Institute for Science and Education Fellow
U.S. Army Research Institute of Environmental Medicine
Natick, Massachusetts, United States
MW

Marques A. Wilson

U.S. Army Research Institute of Environmental Medicine, United States
CC

Christopher T. Carrigan, BS

Research Physiologist
U.S. Army Research Institute of Environmental Medicine
Natick, Massachusetts, United States
NM

Nancy E. Murphy, M.S.

US Army Research Institute of Environmental Medicine
Natick, Massachusetts, United States
DD

Devin J. Drummer, PhD

Postdoctoral Fellow
U.S. Army Research Institute of Environmental Medicine
Newton, Massachusetts, United States
LM

Lee M. Margolis, PhD, RD

U.S. Army Research Institute of Environmental Medicine

Objectives: Exogenous carbohydrate (CHO) oxidation is reportedly reduced when glucose alone is consumed during endurance exercise in an energy deficit (DEF) state. Consuming multiple transportable CHO (glucose + fructose (GLU+FRU)) increases exogenous CHO oxidation compared to GLU alone during energy balance (BAL), but whether these effects are also observed during DEF is unclear. This study aimed to assess the effects of GLU+FRU compared to GLU on exogenous CHO oxidation during endurance exercise under BAL and DEF conditions.

Methods: Eleven participants (sex: 2F/9M, age: 21 ± 3 y, BMI: 26 ± 3 kg/m², V̇O₂peak: 43 ± 5 mL∙kg^-1∙min^-1) completed this double-blind randomized crossover study. Participants completed 4 study arms, each initiated by a bout of cycle ergometry followed by 48 hours of consuming BAL or DEF study diets (100% or 50% energy needs, respectively). After BAL and DEF, participants consumed 80 g GLU or GLU+FRU (53 g GLU, 27 g FRU) before and during an 80 min cycle ergometry bout at 60% V̇O₂peak. Substrate oxidation (g/min) during exercise was determined by indirect calorimetry and tracer techniques with ¹³C-glucose or ¹³C-glucose + ¹³C-fructose.

Results: There was no difference in exercise intensity (62 ± 4% V̇O₂peak, 112 ± 29 watts) between energy status or CHO treatment. Independent of energy or treatment, exogenous CHO oxidation increased (P < 0.001) and endogenous CHO oxidation decreased (P < 0.001) during exercise. Exogenous CHO oxidation was higher with GLU+FRU (0.54 ± 0.13) compared to GLU alone (0.44 ± 0.11, P < 0.001), regardless of energy status. Endogenous CHO oxidation was lower during DEF (0.98 ± 0.40) compared to BAL (1.09 ± 0.40, P < 0.001), but did not differ between GLU+FRU (1.01 ± 0.11) and GLU (1.07 ± 0.11, P = 0.07). Independent of treatment, total CHO oxidation was lower (P < 0.001) and fat oxidation was higher (P = 0.003) during DEF compared to BAL.

Conclusions: These data indicate that exogenous CHO oxidation remains higher when GLU+FRU is consumed before and during endurance exercise in an energy deficit state compared to GLU alone. As such, multiple transportable CHO should be the recommended dietary strategy to increase exogenous CHO oxidation during endurance exercise following suboptimal energy intake.

Funding Sources: Funded by MOMRP; views are not official US Army or DoD policy.