The Effects of Caffeine Administered in Chewing Gum on Mood at Rest and Following Exercise

Abstract

Research has demonstrated that caffeine ingestion and exercise is associated with mood alterations. PURPOSE: The purpose of the current investigation was to determine the effects of caffeine (administered in gum) on mood at rest and following exhaustive exercise. METHODS: Eight male cyclists participated in five separate laboratory sessions, with a one week washout period between sessions. During the first visit, subjects underwent a graded exercise test on an Excalibur 1300Wcycle ergometer to determine maximal oxygen consumption (VO2max) and were familiarized with the Profile of Mood States (POMS). The POMS is a standardized questionnaire that quantifies transient mood state. For each of the next four visits, 3 pieces of chewing gum [caffeine (CAFF) or placebo (PLA)] were administered at 3 time points, 120 min pre-exercise, 60 min pre-exercise, and 5 min pre-exercise. In 3 of the 4 experimental trials, CAFF was administered at one of the three time points (CAFF-120, CAFF-60, CAFF-5) and PLA at the other two time points. During the control trial PLA gum was administered at all three time points. Following baseline measurements, time allotted for gum administration, and a standard warm-up, participants cycled at 75% VO2max (constant Wattage) for 15 min then completed a 7 kj·kg-1 cycling time trial. The POMS was administered at baseline (BASE), 100 min prior to cycling (-100), 40 min prior to cycling (-40), and immediately after cycling (POST). RESULTS: Data were analyzed using a 4 (trial) by 4 (time) repeated measures analysis of variance (ANOVA). The ANOVA revealed no main effect of treatment (p > 0.05); however, a main effect of time (p = 0.008) was observed for changes in POMS scores. Post hoc t-tests revealed that POMS scores decreased from BASE to -100 (p ≤ 0.004), remained stable to -40, then increased following exercise (p = 0.029). The ANOVA also revealed a treatment x time interaction (p = 0.012). Peak change scores were computed and compared with paired samples t-test; peak change scores were higher in the CAFF-120 trial versus PLA (p = 0.017). CONCLUSION: Mood improved overtime at rest and worsened following exhaustive cycling across all treatments. Larger fluctuations in POMS scores were observed when caffeine was administered 120 min prior to exercise.