Stamina
https://www.muscleprodigy.com/study-caffeine-boosts-squatting-power/
https://greatist.com/fitness/can-caffeine-boost-exercise-endurance
https://www.ncbi.nlm.nih.gov/pubmed/11583104
Memory
https://www.verywellmind.com/does-caffeine-improve-memory-21846
Reaction Time
https://elisabeth-carrio.com/experimental-design-caffeine-affects-reaction-time/
https://www.livestrong.com/article/499270-effects-caffeine-has-on-your-reaction-times/
http://denethor.wlu.ca/pc131/sample_lab.pdf
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3942723/
https://www.coffeeandhealth.org/topic-overview/caffeine-and-mental-alertness/
http://scienceline.ucsb.edu/getkey.php?key=915
Heart Rate