These two didn’t look exceptionally muscular. How do they do it? Reminds me of a bad old joke from my music student days. A young, stary-eyed man carrying a violin case gets out of the subway in mid-town Manhattan, staring in wonder. He stops an older gentleman walking down the street and asks, “Excuse me, sir. How do you get to Carnegie Hall?”
The old man simply replies, “Practice, practice, practice.” And so here.