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Iron Man November 2009 Excerpt: Big-Back Basics & The Lats!

Back work has long been an area of controversy in strength training. Questions about lat development are especially prevalent. Find out more.

The Lats
Effective Back Training

Back work has long been an area of controversy in strength training. Questions about lat development are especially prevalent: Is the lat pulldown the best and safest exercise for the latissimus dorsi? Why are most people stronger on a lat pull or a pullup when they use a palms-up grip? Are the lats involved in row-type exercises? Does changing my arm position during rowing exercises affect which back muscles are worked?

A basic understanding of the anatomy and kinesiology of the latissimus dorsi and surrounding structures makes those questions much less intimidating.

Lat Anatomy

The latissimus dorsi is a large muscle with a very broad origin on the vertebrae and ribs of the middle and lower back, tapering into a narrow insertion on the front of the head of the humerus on the upper arm. On the surface it runs in a mostly vertical fashion up the sides of the back, giving the upper body its V-shape.

All of the muscle fibers in the latissimus dorsi are virtually parallel, making the entire muscle participate in the same action on the arm. That’s very different from the pectoralis major, with its two heads and distinctly different fiber angles and actions on the arm. You cannot train “parts” of the latissimus dorsi.

Any discussion of the latissimus dorsi must include a mention of the teres major, which is commonly referred to as the “lats’ little helper” because it contributes to the same action on the arm. It’s impossible to train one without the other.

The origin of the teres major is on the lower edge of the shoulder blade, above the latissimus dorsi. The insertion is on the head of the humerus, in virtually the same spot as the insertion of the latissimus. For that reason you should consider the teres major to be an extension of the latissimus dorsi.


The latissimus dorsi has two main actions involving the arm. It functions in adduction—pulling the arm to the side of the body from an out-to-the-side position—and extension—pulling the arm down from a horizontal position straight out in front of the body. Understanding those two primary actions will be a great tool for handling lat-exercise dilemmas.

Editor’s note: Dustin Parsons is certified by the International Sports Science Association, Contact him at For similar articles visit IM

Get the rest of the article in the November Issue of Iron Man Magazine.