I′ve been goofing around a lot in the gym lately, training much more often and doing way more exercises and sets than I have in years. Here′s something interesting I′ve found.
We normally suggest using a close grip palms up pulldown/chin for several reasons. The first reason is that a close grip makes the lats work through a larger range of motion, and thus stretches the muscle more. I agree with this for sure, for abvious reasons.
The second reason is a little debatable I′ve found. We normally say using a palms up grip puts the biceps in their strongest position, and this is important in properly working the lats. The argument goes that it is only the secondary function of the biceps to move the forearm towards the upper arm, but the primary is supinating the wrist. We must have the wrists supinated to put the bicep in its strongest position, so the bicep will last longer before failing, letting us work the lats harder.
I′m not convinced anymore for the following reasons.
1) In a pulldown, as far as the bicep/arm relationship is concerned, I′m only interested in moving my forearm towards my upper arm, not in supinating my hand. If it′s only the secondary function of the bicep to move the forearm to the upper arm, what difference does it make what the primary function is, or if I satisfy it?
2) I′ve noticed it makes no positive difference to have my palm up during a pulldown, except for the fact that it′s become more comfortable over the yeas with a close grip. I′m equally strong, if not stronger, with a overhand grip.
3) And here′s the kicker, I can hammer curl waaaaaaaay more than I can palms up dumbell curl. I figure it′s because I′m using the brachialis more. I don′t know if it′s the primary function of the brachialis to move the forearm towards the upper arm, but if it is, it would make sense to use it. Regardless, being stonger with the neutral grip of a hammer curl in moving the forearm to the upper arm is significant when trying to work the lats.
I′ve noticed that I can lift just as much, if not more, on a palms over pulldown, and my biceps don′t feel as hit when I′m done compared to the palms up variety. I guess, if you don′t do any direct bicep work, then it might be best to keep the palms up grip, but I don′t think it′s necessary for maximum lat stimulation for the reasons stated above (comparative strength, hammer curls, primary/secondary functions). If, however, you do direct bicep work, especially in the same workout, using a palms down grip may leave your biceps a bit fresher for their own set later.