Scientists have found that you don’t need 

to lift heavy weights to build up muscles.

Most body builders and weightlifters try to lift the heaviest weights possible, but a study has shown that lifting weights 70% lighter can achieve the same result.

Researchers at McMaster University in the US say that the main thing is to reach muscle fatigue, and lift weights until you can’t lift them any more.

In tests, volunteers lifted weights that weighed either 90% or 30% of their best-ever lift. Both increased muscle building four hours after exercise, but only the men that lifted the lighter weights were showing the same response 24 hours later.