But if they're not used right, they can strain muscles and even cause back pain.
Montgomery strained a muscle running before the first full practice.
"We can participate in sports with no concern about straining a muscle."
"With the light gravity it's hard to imagine anyone straining a muscle."
He strained a muscle in his left side Friday and was placed on the disabled list yesterday.
You can strain a muscle with an unexpected pull or twist.
He strained a muscle on his left side in the first inning, and pitching through the pain did not help.
He thought he had strained a muscle, but it didn't go away.
He also strained a muscle in his lower leg.
Running out a ground ball to end the second inning, he strained a muscle in his upper thigh.