AUTHOR=Jiménez-Martínez Pablo , Alix-Fages Carlos , Janicijevic Danica , Miras-Moreno Sergio , Chacón-Ventura Sara , Martín-Olmedo Juan J. , De La Cruz-Márquez Juan Carlos , Osuna-Prieto Francisco J. , Jurado-Fasoli Lucas , Amaro-Gahete Francisco J. , García-Ramos Amador , Colado Juan C. 

TITLE=Effects of phenylcapsaicin on aerobic capacity and physiological parameters in active young males: a randomized, triple-blinded, placebo-controlled, crossover trial

JOURNAL=Frontiers in Physiology

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2023.1190345

DOI=10.3389/fphys.2023.1190345

ISSN=1664-042X

ABSTRACT=<p><bold>Objective:</bold> Phenylcapsaicin (PC) is a new capsaicin analog which has exhibited a higher bioavailability. This sudy assessed the effects of a low dose (LD) of 0.625 mg and a high dose (HD) of 2.5 mg of PC on aerobic capacity, substrate oxidation, energy metabolism and exercise physiological variables in young males.</p><p><bold>Materials and methods:</bold> Seventeen active males (age = 24.7 ± 6.0 years) enrolled to this randomized, triple-blinded, placebo-controlled, crossover trial. Participants attended the laboratory on 4 sessions separated by 72–96 h. A submaximal exercise test [to determine maximal fat oxidation (MFO) and the intensity at MFO (FATmax)] followed by a maximal incremental test (to determine VO2<sub>max</sub>) were performed in a preliminary session. The subsequent sessions only differed in the supplement ingested [LD, HD or placebo (PLA)] and consisted of a steady-state test (60 min at FATmax) followed by a maximal incremental test. Energy metabolism, substrate oxidation, heart rate, general (gRPE) and quadriceps (RPEquad) rate of perceived exertion, skin temperature and thermal perception were tested.</p><p><bold>Results:</bold> Clavicle thermal perception was lower in HD compared to PLA and LD (<italic>p</italic> = 0.04) across time. HD reduced maximum heart rate in comparison to PLA and LD (<italic>p</italic> = 0.03). LD reported higher general RPE (RPEg) values during the steady-state test compared to PLA and HD across time (<italic>p</italic> = 0.02). HD and LD elicited higher peak of fat oxidation during the steady-state test compared with PLA (<italic>p</italic> = 0.05). Intra-test analyses revealed significant differences for fat oxidation (FATox) in favor of HD and LD compared to PLA (<italic>p =</italic> 0.002 and 0.002, respectively), and for carbohydrate oxidation (CHOox) (<italic>p =</italic> 0.05) and respiratory exchange ratio (RER) (<italic>p =</italic> 0.03) for PLA. In the incremental test, only general RPE at 60% of the maximal intensity (W) differed favoring HD (<italic>p</italic> ≤ 0.05).</p><p><bold>Conclusion:</bold> Therefore, PC may contribute to increase aerobic capacity through the improvement of fat oxidation, maximum heart rate and perceptual responses during exercise.</p>