I'm an avid runner (50-70km/week) and I've been running for 5 years. I run long distances on trail.
Seems that although it increases performance and stamina for me it also brings my heart rate up, which is not desirable in most cases since I'm training ~80% of the time in zone 2 (aerobic). At given pace I can have few bits higher HR when caffeinated (between 5 and 10 bpm) which means that I need go go slower in order to stay in zone 2.
For me it's a tool that I'm using during races. Also worth noting is that caffeine works on me really well.
Seems that although it increases performance and stamina for me it also brings my heart rate up, which is not desirable in most cases since I'm training ~80% of the time in zone 2 (aerobic). At given pace I can have few bits higher HR when caffeinated (between 5 and 10 bpm) which means that I need go go slower in order to stay in zone 2.
For me it's a tool that I'm using during races. Also worth noting is that caffeine works on me really well.