The purpose of this investigation was to examine the acute effects of consuming two different fitness drink formulas on the physiological response at rest and to exercise in healthy men and women.
Thermogenic fitness drinks containing \~200mg of caffeine have been reported to accelerate the metabolism, increase energy, and consequently promote increased fat oxidation. However, determination of the efficacy of lower caffeine concentrations may provide additional options for individuals with preferences for reduced caffeine intake. Therefore, the aim of this study was to evaluate different fitness drink formulas containing a total of 100mg and 140mg of caffeine on the physiological response at rest and to exercise. This study utilized a randomized, double-blind, placebo-controlled design. All participants completed three testing visits during which they consumed the placebo, the 100mg caffeine formula, and the 140mg caffeine formula. Blood samples, blood pressure, heart rate, resting energy expenditure, substrate oxidation, and neurocognitive assessments were collected at baseline and repeated 30, 60, and 90 minutes post-ingestion. Immediately following the last cognitive assessment, a maximal graded exercise test with gas analysis was conducted on a cycle ergometer to evaluate physical performance and maximal fat oxidation during exercise as well as the physiological response prior to and following exercise.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
OTHER
Masking
DOUBLE
Enrollment
56
Single drink provided following baseline assessments
Kinesiology Laboratories
Orlando, Florida, United States
Change in resting energy expenditure/substrate oxidation
Estimates from gas exchange analysis via indirect calorimetry
Time frame: Baseline, 30, 60, and 90 min post-ingestion
Change in energy expenditure/substrate oxidation in response to exercise
Estimates from gas exchange analysis via indirect calorimetry
Time frame: >90 min post-ingestion (pre/peri/post maximal graded exercise test)
Change in resting serum glycerol
Obtained from blood draw of the superficial forearm vein
Time frame: Baseline, 30, 60, and 90 min post-ingestion
Change in oxygen consumption/carbon dioxide production in response to exercise
Estimates from gas exchange analysis via indirect calorimetry
Time frame: >90 min post-ingestion (pre/peri/post maximal graded exercise test)
Change in resting minute ventilation
Estimates from gas exchange analysis via indirect calorimetry
Time frame: Baseline, 30, 60, and 90 min post-ingestion
Change in minute ventilation in response to exercise
Estimates from gas exchange analysis via indirect calorimetry
Time frame: >90 min post-ingestion (pre/peri/post maximal graded exercise test)
Change in Automated Neuropsychological Assessment Metrics (ANAM) screening
Measures from mood scale, go/no go test, Stroop test
Time frame: Baseline, 30, 60, and 90 min post-ingestion
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Change in resting blood pressure response
Measured via automated blood pressure monitor
Time frame: Baseline, 30, 60, and 90 min post-ingestion
Change in resting heart rate/heart rate variability
Measured via chest-based heart rate monitor
Time frame: Baseline, 30, 60, and 90 min post-ingestion
Change in heart rate/heart rate variability in response to exercise
Measured via chest-based heart rate monitor
Time frame: >90 min post-ingestion (pre/peri/post maximal graded exercise test)
Change in power output
Obtained via cycle ergometer during the maximal graded exercise test
Time frame: >90 min post-ingestion