One of two of the most common and questionable tips for golfers…”keep your left arm straight”. (This is of course for right handers). The other is keep your head down. Is keep your left arm straight a myth or a must? I believe it to be somewhat of an old wives tale, or rather just vague. Keep it straight where? When? Most of us know that we want to keep it straight at address. If we do, the club is resting on the ground right behind the ball, correct? Well if we return to the ball with it bent, we have a problem. That problem is a whiff or at very best a thin or topped shot. So it is an absolute must that it be straight at impact. A broken down leading arm is no different really than a broken shaft. If you strike a ball with a bent club shaft you will surely lose power. A lever that is broken is not a pressure cooker. And that’s simply what we want to do…put pressure down into the golf ball. A player with a wide arc for instance, someone 6’5″ with long arms, is going to hit the ball much further than a player with a narrow arc such as a 5’2″ player with short and bent arms. So it’s easy to see how a bent arm at impact affects both your power and your consistency.
Is it imperative to keep the leading arm straight throughout the entire back swing then? My answer is no. It sure makes things more simple and requires less compensations though. Many a good player, even tour players have had their’s bent at the top of the swing. Yet, they do return to impact with it straight.
The real question here is why do many players struggle with keeping the leading arm straight? The answer I believe is two fold. 1) They lack flexibility in their core and upper body particularly the lats and delts. 2) Their back arm collapses. Yes the back arm is the real culprit, not the leading arm. The leading arm wants to stay straight and function as a lever. When the back arm pulls in, the front arm goes with it.
If collapsing your leading arm at the top of the swing is a problem for you, I urge you to work on flexibility and focus on the width of your rear arm. Practice swinging out or back, not up!