According to research, using a thicker bar leads to greater muscle fiber recruitment in the arms and thereby faster muscle size gains. (fitnessandpower.com)
Suspension work also lends itself well to static contractions — simply holding yourself in a position of tension — which is an often overlooked but valuable method for those seeking muscle size gains. (onnit.com)
I don't believe it would be accurate to say that for every 1 % increase in muscle size you gain 4.6 % or 7.3 % in overall 1RM strength because there are simply too many variables for that to be true. (trainingscience.net)