You're Correct!

If you are looking to hit the ball as far as possible with your golf swing, it is really important that you create the widest swing arc.

Your swing arc is simply how your club head is travelling round you as you swing the club. As you swing back on your back swing you should work on keeping your left arm completely straight throughout your back swing, as this makes sure the club head is being swung as far out around you as possible and it creates the widest circle for the club head to travel on around you.

The same is true as you swing the club head back towards the golf ball, on your down swing and into impact. If you now extend your left arm, so your left arm is completely straight as you are connecting with the ball, the club head is as far away from you as possible, so you are on the biggest and widest swing arc. As you are striking the golf ball with the club head, extend your right arm out so it explodes through impact, acting like a lever and that will create a really wide circle for the club head to swing through and into the follow through on. This is really important, because the wider your golf swing is, or the bigger your swing arc is, the wider the circle that the club head has to travel on and the more time you have got to pick speed up, as your club head travels around it. The faster your club head is travelling and the faster club head speed you have, the further you will hit the ball.

Extending your arms through impact really does create a lot of power and lets you hit the ball as far as possible. A great drill to help you with this is to get an impact ball, or get a very small football that would fit between your forearms at address. A tennis ball would be too small and a full sized football would be too big. You could find something that is about that size or create something, maybe by using an old cushion and then work on holding this impact ball between your forearms as you swing through. If your forearms stay close together, your arms will be extending out and into the follow through and you will be pushing that impact ball away from your body, rather than pulling it into you. If you are pulling the impact ball into you and you are dropping the impact ball, it shows that your arms are not extending. You are buckling at your elbows, rather than extending and straightening your arms out through the shot.

That is a really good practise drill to help you get the feel of how to extend those arms through impact.

Bent elbows during impact is a classic mistake that leads to poor strikes, inconsistence distances and a lack of accuracy.

If your hands stay very close to your body as you come into impact and especially on the follow through, you are not fully extending your arms. You are not making the widest swing you possibly could, you are not making the biggest swing arc and you will be slowing the club head down to guide it round this smaller circle, meaning you will lose a lot of club head speed and you will lose a lot of length to your golf shot.

Work on really extending your arms through impact, left arm straight as you impact with the ball and then once you have impacted with the ball, with the left arm straight, extend the right arm so that it acts like an exploding lever through the shot, into a fully extended position. This will help you to create a lot of club head speed and hit the ball a lot further.