People can't guess how many more reps they can do

People who lift weights for over a year often guess wrong about how many more reps they can do before getting tired—they usually think they can do about 2 fewer than they actually can.

Even if you've been lifting weights for a year, you might still not be good at guessing how many reps you have left in the tank, because people in a study kept thinking they could do more than they actually could.

When people do strength exercises like knee extensions, how hard they think they're working doesn't always match how hard their body is actually working. Even trained athletes often think they can't do more reps when they actually could.

People aren't very good at guessing how close they are to muscle failure when doing many reps of weightlifting.

When people test how many times they can lift a weight, their performance changes from day to day. This makes it hard to predict their true ability. Using a daily adjustment method helps make the results more consistent and shows that people can actually do more reps than what standard tests suggest.