Koozehchian, Majid Surena (2017-02). Effects of Ingesting a Preworkout Supplement for 7 Days on Exercise Performance and Cognitive Function. Doctoral Dissertation.
Thesis
We examined the effects of ingesting two pre-workout supplements (PWS) on cognitive function, perceived readiness, and exercise performance related parameters. Resistance-trained participants (N=19) were randomized to a double-blind, cross-over (7-day washout), placebo-controlled study supplemented with: (1) Placebo (PLA); (2) PWS (caffeine, creatine nitrate in a 2:1 ratio as a salt, ?-alanine, arginine alphaketoglutarate, ascorbic acid, N-acetyl tyrosine, Mucuna pruriens), and (3) PWS150 at ~150% of the PWS dose. Participants were tested on hemodynamic responses, resting energy expenditure, cognitive function (Stroop Color-Word test), self-perceived readiness, three sets of bench and leg press at 70% of 1RM, a 30-sec anaerobic capacity test, side effect questionnaires, and donated blood samples before and/or after acute ingestion, then after 7 days of supplementation. Data were analyzed by GLM and presented as mean (SD) or mean change (95% CI). Significant improvements in Stroop Word testing were observed for PWS (6.57 counts, 95% CI 1.36, 11.8) and PWS150 (11.5 counts, 95% CI 6.26, 16.6), but not PLA (1.31 counts, 95% CI -3.89, 6.52). Significant changes in Stroop Color testing were observed for PWS150 (8.1 counts, 95% CI 4.52, 11.6) and PLA (4.47 counts, 95% CI 0.89, 8.05), but not PWS (2.31 counts, 95% CI -1.26, 5.89). Similar results were observed for Word-Color. When all domains were summed, PWS150 (27.4 counts, 95% CI, 16.1, 38.7) and PWS (12.3 counts, 95% CI, 1.0, 23.5) showed significant improvements, but not PLA (11.3 counts, 95% CI, - .002, 22.5). We observed significant improvements in Wingate mean power for PWS150 (26.0 watt, 95 CI, 1.85, 50.3), but not PWS (-3.83 watt, 95 CI, -28.7, 21.0) and PLA (8.88 watt, 95 CI, -17.5, 35.2). No significant or adverse changes were observed for hemodynamic, thermogenic, and hematologic variables. The PW150 demonstrated consistent improvements in cognitive function; yet was unmatched by changes in self-perceived readiness or other measured parameters associated with exercise performance.
