The Acute Effects of Exercise and Caffeine on Working Memory During Acute Caffeine Deprivation

Participants will be asked to keep consumption of caffeine before the first visit to their regular dose (ex. morning coffee) and to abstain from alcohol and drugs for at least 18 hours prior to testing. Participants will be urged to arrive at the same time for each visit. Upon arrival to the Exercise and Health Psychology lab (located in room 408 of the Arthur and Sonia Labatt Health Science Building at Western University) participants will be given the letter of information and asked to sign the informed consent form. Participants will also be asked to complete a demographic survey, PAR-Q (Physical Activity Readiness Questionnaire) readiness for exercise, Godin Leisure-Time Exercise Questionnaire, CCQ-R (Caffeine Consumption Questionnaire), and the CWSQ (Caffeine Withdrawal Symptom Questionnaire). Vitals (heart rate and blood pressure) will be assessed following the completion of the questionnaires as well as post assessment in the seated position. Prior to evaluation on the N-back task (cognitive memory task described below) a practice stage with be conducted until the participant can consistently score 75% or higher on three consecutive trials to eliminate a learning effect. After establishing familiarity, a baseline cognition score will be conducted through the n-back assessment.

Prior to arrival for the second visit, participants will be asked to refrain from caffeine for at least 24 hours and to abstain from abstain from alcohol and drugs for at least 18 hours prior to testing. During the second visit (approximately 24 hours after the first) the participants will complete the pre-caffeine or pre-exercise questionnaire, the CWSQ and vitals will be monitored pre and post intervention. Caffeine abstinence will be validated through self-report with the use of deception (participants being told that their saliva sample is being tested for the presence of caffeine). To collect saliva, a cotton swab will be placed under their tongue for 1minute, placed into a tube, and then a co-investigator will discard the tube into a biohazard deposal container immediately. Participants will then complete another n-back assessment.

The participants will be randomized into either the moderate intensity exercise or caffeine ingestion group. The interventions are as followed; Moderate Intensity Exercise will consist of a 20-minute bout of moderate intensity aerobic exercise. Exercise will consist of a 2-minute warm-up, followed by 15 minutes of walking at a rate, which will allow you to reach 2/3 of your max heart rate (moderate intensity exercise= (220-age) x 0.6), and then a 3-minute cool down on a treadmill (together equaling 20 minutes). HR will be monitored through heart rate monitors worn by the participants. The caffeine ingestion group will ingest 1.2 mg/kg of caffeine in powder form with water to drink, after ingestion of caffeine participants will wait 20 minutes to ensure peak plasma levels. The post intervention n-back assessment will begin within two minutes of the completion of either intervention.

Inclusion criteria

• Are over the age of 18 years
• Consume at least 150 mg of caffeine a day
• Do not have any cognitive problems
• Are not pregnant
• Do not have a medical condition that prevents you to exercise
• Do not have an orthopaedic limitation
• Have access to a telephone or an email account for communication
• Can read and write in English

Exclusion criteria

• Participants taking prescription medication for depression or anxiety
• Participants that cannot give informed consent will be excluded.