Introduction: The acute energizing effect of exercise and caffeine has never been examined in a single study of adults with chronic sleep deprivation but evidence from a study of this type could help individuals choose between these two common alertness-enhancing options.
Aim: The apriori primary aim of this experiment was to compare the influence of 10-min of low-to-moderate intensity stair walking to the consumption of capsules containing 50mg caffeine or flour (placebo) on feelings of energy in physically active, college female caffeine users with chronic insufficient sleep. Effects on secondary outcomes related to feelings of energy also were assessed.
Material-method: A repeated measures crossover experiment was conducted with 18 college women (18-23years) who reported (i) daily caffeine consumption that was not extreme (40-400mg), (ii) typical leisure time physical activity that was not extreme (at least 2 weekly mild 15-min or longer bouts and no >5 strenuous 15-min or longer bouts), and (iii) sleeping <45h per week. Mood states (POMS-BF), focused on energy feelings (vigor), as well as working memory (N-back), sustained attention (CPT), simple reaction time (SRT), and motivation to complete the cognitive tasks were measured before and after a 10-min exercise condition (20min seated rest followed by 10min of low-to-moderate intensity stair walking) and compared to both a caffeine condition (50mg caffeine capsule followed by 30min of seated rest) and a similar flour (placebo) capsule condition. Condition (exercise, caffeine, placebo)×Time (Baseline, Post-1, Post-2, and for mood Post-3) ANCOVAs (controlling for Condition order) tested the hypothesized effects.
Results: Condition×Time interactions showed that stair walking increased POMS-BF vigor at Post-1 compared to both placebo and caffeine. Other interactions were not significant.
Conclusion: A brief bout of low-to-moderate intensity stair walking has transient energizing effects that exceed a low dose of caffeine for active young women with chronic insufficient sleep.
Keywords: Attention; Energy; Exercise; Fatigue; Reaction time; Vigor.
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