The effect of caffeine ingestion on mood state and bench press performance to failure
 
 
Journal Title (Medline/Pubmed accepted abbreviation): J Strength Cond Res
Year: 2011
Volume: 25
Number: 1
Page numbers: 178-185
doi (if applicable): N/A

Summary of Background and Research Design

Background:Caffeine ingestion enhances performance and reduces ratings of perceived exertion (RPE) in submaximal aerobic endurance events. Caffeine has also been suggested to improve performance in high-intensity exercise, although results of several studies examining short-term resistance exercise, such as 1 rep max (1RM) bench press, have been mixed. The variability of these previous results may be because of variations in study methodology and inconsistent control of dietary practices, hydration status, prior caffeine intake, or training history. Similarly, the effect of caffeine ingestion on RPE or mood state during resistance training has been variable.

Hypothesis/purpose of study: To examine the effect of acute caffeine ingestion on resistance exercise to failure, RPE, and mood state, pre- to postexercise, in moderately trained men.

Subjects:The study included 13 men having moderate (ie, ~200 mg/d) caffeine intake who were regular participants of a university-level sports program and who had resistance training experience (mean [SD]: age, 22.7 [6.0 years])

Experimental design: Double-blind, within-subjects, repeated-measures design

Treatments and protocol: Athletes completed a preliminary exercise session to determine each participant’s 1RM on the bench press. On each of the 2 testing days, participants ingested 5 mg/kg of caffeine diluted into 250 mL artificially sweetened water or placebo containing 250 mL of just the artificially sweetened water 60 minutes before exercise trial. After a 5-minute submaximal warm up, 1 set of bench press exercise was conducted to failure at 60% 1RM. Total weight lifted (kg) was calculated by multiplying mass lifted by number of completed repetitions. Ratings of perceived exertion were obtained immediately after failure using the Borg CR10 RPE scale. Capillary blood samples taken 3 minutes after each test were used to assess plasma blood lactate (PBLa). Mood state was assessed 60 minutes before experimental or placebo ingestion and immediately after failure using the Brunel Mood State Inventory (BRUMS; 24-item questionnaire consisting of 6 subscales relating to the mood states of Anger, Confusion, Depression, Fatigue, Tension, and Vigor).

Summary of research findings:
  • Participants completed significantly more mean [SD] repetitions (22.4 [3.0] vs 20.4 [3.4]; P = .031) and lifted significantly greater weight (1,147.2 [261.4] kg vs 1,039.4 [231.7] kg; P = .027) for caffeine vs placebo, respectively
  • Likewise, participants’ mean peak heart rate [PHR] (beats/min; P = .0001) and mean PBLa (mmol/L; P = .002) were significantly higher after caffeine ingestion
  • In contrast, RPE was not different across conditions (P = .082)
  • Mood state scores for Vigor were greater (P = .001) and Fatigue scores lower (P = .04) following caffeine ingestion
  • No significant effects of caffeine intake on the Anger, Confusion, Depression and Tension subscales of the BRUMS were observed (P > .05)
  • Fatigue scores were greater postexercise compared with pre-exercise scores (main effects, P = .001)

Interpretation of findings/Key practice applications:

Caffeine ingestion enhances performance in short-term, resistance exercise conducted to failure and may improve mood state following exercise in trained individuals. Athletes could enhance performance, gain greater physiologic loading, reduce fatigue, and improve vigor by ingesting caffeine before resistance exercise. Limitations of this study include short duration of exercise and only 1 exercise instead of a more complete range of exercises to represent the diversity of athletic training. A full-body workout may yield different results than those of this study using a single muscle group. In addition, hydration status and pain perception were not assessed. Finally, because of the noticeable effects that caffeine can have on mood or subjectively perceived “energy” levels, the potential exists that the subjects could have correctly guessed the identity of the treatments and may have altered their performance intensity as a result. A pre-study investigation of the subjects’ ability to discern between treatments would have been helpful.
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