People are better at guessing how many chest press reps they can do before getting tired compared to leg press reps, with guesses being off by only about one rep for chest press but more for leg press.

The study looked at how well people can guess how many more times they can lift weights before getting too tired, and it found that for chest exercises, guesses were very close to reality for up to 5 more reps, but for leg exercises, guesses were only close for up to 3 more reps, just like the claim says.