There is debate as to how much posing or isometrics can build muscle. One interesting factor regarding posing involves Tom Platz. Prior to Tom Platz in the late 1970s, people had mainly seen extreme muscle striations in the pecs, delts, lower back, and sometimes triceps.
When Platz arrived on the scene with disproportionately developed quadriceps, etched with striations, people freaked out. In addition to training his quads with heavy multiple sets of squats and leg extensions he would pose and stretch them like crazy. Intense posing and static contraction brought detail to Platz’s legs that no one had seen before. Shortly after that, you started to see more bodybuilders with striated quads. Some may say the detail in the quads is because bodybuilders have lower body fat percentages nowadays when competing, and that’s a factor. However, you still see the striations on the quads when obesely bulked, over 300 pound bodybuilders guest pose. I’ve seen photos of a 330 pound Nasser El Sonbaty who still had striated quads. That’s a much heavier body fat percentage than non-striated thighed Schwarzenegger ever had.
Post-Platz, striated quads were a must have body part. You see the same thing with striated glutes. No one went overboard flexing their butt muscles in the 70s but that became another must-striate body part post-Richard Gaspari. Yes, leanness is a huge factor but so is intense posing and intense locked-out contraction to bring out the detail. If you disagree with posing bringing out detail, argue with Arnold Schwarzenegger, he has said it before in print. Recent drugs could be another factor but you started to see the same striated quads Platz had when bodybuilders started to do more locked-out static contractions with their quad muscles with weights on the leg extension machine(peak contraction) or through intense posing with the quads fully contracted and the leg fully extended straight ala Platz in the photo below.
Tom Platz’s revolutionary striated quadriceps below.