|Yes, it may in fact make sense to shovel down another scoop of your preworkout if you train for 2h. Just try to remain below the sign. stress-dosage of 600-800mg caffeine/day (Beaven. 2008).|
The aim of said study was to assess if low and moderate doses of caffeine delivered in a carbohydrate-electrolyte solution (CES) late in exercise improved time trial (TT) performance. Fifteen (11 male, 4 female) cyclists (22.5 ± 0.9 yr; 69.3 ± 2.6 kg; VO2peak, 64.6 ± 1.9 ml / min / kg-1) completed four double-blinded randomized trials.
Subjects completed 120 min of cycling at ~60% VO2peak with five interspersed 120 s intervals at ~82% VO2peak, immediately followed by 40 s intervals at 50 W. Following 80 min of cycling, subjects either ingested a 6% CES (PL), a CES with 100 mg (low dose, 1.5 ± 0.1 mg / kg body mass) of caffeine (CAF1) or a CES with 200 mg (moderate dose, 2.9 ± 0.1 mg / kg body mass) of caffeine (CAF2).
|Figure 2: We do have good evidence that high dose caffeine can be too much of a good thing... at least if you measure "good thing" via the testosterone to cortisol ratio which will decrease after 800 mg by 14%; ± 21% (Beaven. 2016).|
- Beaven, C. Martyn, et al. "Dose effect of caffeine on testosterone and cortisol responses to resistance exercise." International journal of sport nutrition and exercise metabolism 18.2 (2008): 131.
- Cox, Gregory R., et al. "Effect of different protocols of caffeine intake on metabolism and endurance performance." Journal of Applied Physiology 93.3 (2002): 990-999.
- Talanian, Jason L., and Lawrence L. Spriet. "Low and Moderate Doses of Caffeine Late in Exercise Improve Performance in Trained Cyclists." Applied Physiology, Nutrition, and Metabolism ja (2016).