Just think of a soccer kick as an easy example of antagonistic muscle pairs. As the player flexes their knees to kick the ball, the hamstrings (agonists) contract to make it happen, while the quads
(antagonists) lengthen and relax to allow for the movement. By the end of the kick the quads engage (agonists) while the hamstrings lengthen and relax (antagonist). It's this harmonious relationship between the muscles that allows for one smooth motion. As you can imagine having a weaker muscle can inhibit a motion and make it less powerful, since you actually need equal strength in both muscles to make it happen!

While soccer is just one example, there are so many antagonist muscle pairs in the body, including well known ones like the triceps and biceps, or the gluteus maximus and the hip flexors. So, if you're ever inspired to achieve greater performance in your sport remember to target a wider range of muscles, including antagonistic muscle pairs since this will result in maximum strength!