Caffeine has shown to acutely increase alertness (Lieberman et al 2002), performance & decrease onset of fatigue (Spriet et al 1992) thus can aid in increasing workout intensity & volume which are key drivers of hypertrophy (Schoenfeld et al 2016). How much? ~2-6 mg/kg seem to be the sweet spot (Goldstein et al 2010).
Research CONSISTENTLY supports the effectiveness of creatine (CR) for improving anaerobic capacity, max power, strength & an overall enhanced quality of training leading to a potential 5-15% greater gain in strength & performance vs placebo (Kreider et al 2003). How much? A simple guideline of 3–5g/day will likely be suffice (Williams et al 1999, Kreider et al 2004).
As it’s well known that a positive protein (PRO) balance is required for building muscle (Tarnopolsky et al 1988), for those who cannot consume the required >1.6g/day (Herda et al 2013, Morton et al 2017), PRO powders can aid in bringing their intake up to the required amount & hence aid with building muscle. How much? However, much you need to bring you up to >1.6g/kg/day.
L-citruline (Sureda et al 2010) & arginine (Bode‐Böger et.al. 1998) can increase nitric oxide production which can then aid in vasodilation (the widening of blood vessel walls) & an increased blood flow to working muscles which can then contribute to enhanced performance & thus hypertrophy. How much? 6-8g preferably consumed in the 1hr prior to exercise (Sureda et al 2010).