The muscle that extends the forearm when doing push-ups is the

Biceps brachii

Explanation:

Biceps brachii is the skeletal muscle which is involved in supporting the movement of shoulder and elbow. This muscle is found on the front of the upper arm between the elbow and the shoulder. The functions of this muscle are listed here -

the cells uses some of the atoms of the glucose molecules to atp molecules. the atoms of the glucose molecules will then be converted into energy which will be eventually stored in atp. the energy produced which are stored in atp are coming from the glucose’s chemical bonds.