Do Glucose and Caffeine Nasal Sprays Influence Exercise or Cognitive Performance?
BACKGROUND
Nasal spray (NAS) containing caffeine (CAF) or glucose (GLUC) activates sensory(motor) cortices.


OBJECTIVE
To investigate the influence of CAF or GLUC NAS on exercise and cognitive performance.


METHODS
Eleven male subjects (age 22 ± 2 y) performed a maximal cycle test and 2 familiarization and 3 experimental trials. Each trial included a 30-s Wingate test and a 30-min time-trial (TT) performance test interspersed by 15 min of rest. Before and after each exercise test a Stroop task was conducted. Placebo NAS with or without CAF or GLUC was provided before each exercise session and at each completed 25% of the TT. Exercise-performance, physiological, and cognitive measures were obtained. Magnitude-based inferences determined the likelihood that NAS solutions would be beneficial, trivial, or negative to exercise-performance measures based on the smallest worthwhile effect. Physiological and cognitive measures were analyzed using (non)parametric tests (P < .05).


RESULTS
GLUC NAS substantially increased the average power output during the TT (very likely beneficial: 98%). No further worthwhile exercise-performance enhancements were found for both substances. In addition, no significant differences in physiological and cognitive measures were observed. In line with mouth rinsing, GLUC was shown to substantially enhance endurance performance, probably due to the activation of the olfactory pathway and/or extra-oral sweet-taste receptors.


CONCLUSIONS
GLUC NAS enhances endurance performance, which indicates a novel administration route. The higher activity in sensory brain cortices probably elicited the ergogenic effect. However, no further physiological and cognitive changes occurred, indicating that higher doses of substrates might be required.
Kevin
K
De Pauw
Bart
B
Roelands
Jeroen
J
Van Cutsem
Lieselot
L
Decroix
Angelica
A
Valente
Kim
K
Taehee
Robert B
RB
Lettan
Andres E
AE
Carrillo
Romain
R
Meeusen
D054874:Athletic Performance / Q000502:physiology*; D002110:Caffeine / Q000008:administration & dosage*; D003071:Cognition / Q000187:drug effects*; D004311:Double-Blind Method; D005080:Exercise Test; D005947:Glucose / Q000008:administration & dosage*; D006801:Humans; D008297:Male; D059085:Nasal Sprays; D058573:Performance-Enhancing Substances / Q000008:administration & dosage*; D057190:Stroop Test; D055815:Young Adult
D059085:Nasal Sprays; D058573:Performance-Enhancing Substances; D002110:Caffeine; D005947:Glucose
Stroop; Wingate; insufflator; time trial