Are you just taking this sample from a random time you looked at someone in the gym? There's a very good chance that these "bulked up" guys were near the end of

Are you just taking this sample from a random time you looked at someone in the gym? There's a very good chance that these "bulked up" guys were near the end of their workout or have already heavily fatigued their back somehow. Either that, or they probably had a lot of bodyfat in which case obviously body weight exercises for reps wouldn't be their strong suit.