The phrase "test their limits" is grammatically correct and can be used in written English.
It means to push or challenge someone or something to see how much they can handle or how far they can go. Example: The coach wanted to test their limits by making them run an extra mile during practice.
The race attracts a global cast of athletes who want to test their limits.
Humans test their limits in an endless variety of ways, but none is simpler or more elemental than breath-holding.
He would push them, test their limits, and they were able to handle the intensity of his management, winning the Premier League in 2005 and 2006.
At the Canyon Ranch, people are urged to test their limits, but they're not forced to do what they don't want to.
The one-year master's program is designed for experienced professionals who are motivated to test their limits and change the world.
You have to laugh with a person, test their limits, go back and forth, touch them, reveal something true about yourself.
Each morning I arrive to train and watch these kids pushing themselves; testing their limits.
"You have 300 young people, many away from home for the first time, testing their limits," he said.
The mathematical equations needed to calculate the transport of water from the main house's well to the produce in the fields tested their limits.
That's the essence of the mad tracking shot: the sense, so rare in the essentially detached medium of film and TV, that we're watching a real-time spectacle of actors and technicians testing their limits in the moment.
As a result, longstanding assumptions about the role the Net can play in the fight against terrorism are being challenged, even as experts say that investigators are likely to be relying on Internet tools -- and testing their limits -- as never before.
