Biceps recruitment with lat pulldowns

The little-known lat pulldown with a pronated grip is used for its major recruitment of the latissimus dorsi. One if its variations, the lat pulldown with a supinated grip, is used for its mechanical advantage for increasing biceps activation. But is this what really happens? That’s what we’ll find out in today’s column. Let’s first consider the various studies on the difference of how the biceps are recruited according to whether the exercise is performed with a pronated or supinated grip. Two studies took a look at the lat pulldown and one addressed pull-ups vs. chin-ups.
Study 1 A first study (Lehman et coll., 2004) analyzed four training exercises that activate the latissimus dorsi, the biceps brachii and the middle trapizeus/rhomboids muscle groups. The training tasks examined were:

1. The forward lat pulldown with a pronated grip (150% of the bi-acromial distance, or the distance between the two acromions)
2. The lat pulldown with a supinated grip (100% of the bi-acromial distance)
3. The seated row without shoulder-blade adduction (hands in neutral position, 6 inches apart)
4. The seated row with shoulder-blade adduction (hands in neutral position, 6 inches apart)

The findings show no exercise task influenced biceps brachii activation (see the table below). While muscular recruitment is constant across the four tasks, it changes for the other muscle groups. For example, the latissimus dorsi is activated more by the seated row with shoulder-blade adduction than by the lat pulldown. This first study therefore concludes that the lat pull-down with a supinated grip does not activate the biceps more, despite its mechanical advantage.

 

Study 2 A second study (Lusk et coll., 2010) also attempted to answer this question by analyzing latissimus dorsi, middle trapezium and biceps brachi recruitment in four different movements:

1. The lat pulldown with a narrow pronated grip (about the bi-acromial width)
2. The lat pulldown with a wide pronated grip (about the distance between the little fingers when the individual is an anatomical position [standing, the arms along the body, palms turned forward])
3. The lat pulldown with a narrow supinated grip (about the bi-acromial width)
4. The lat pulldown with a wide supinated grip (about the distance between the little fingers when the individual is an anatomical position)

This study’s findings showed a significant increase in latissimus dorsi activity when the forearm was in a pronated, as opposed to a supinated, position. However, it would seem that the width of the grip caused no observable difference in activation (see the figure below).

What’s more, no difference was observed (see table below) in middle trapezium and biceps brachii activation.

Study 3 The third study (Youdas et coll., 2010) analyzed three types of bar exercises. The first used a pronated traction for the entire movement (a pull-up), a second was a supinated traction for the whole movement (a chin-up) and a last was pronated grip for the beginning of the movement and a supinated grip for the end of the movement (a perfect pull-up) (see the figures below). The results showed that there is no advantage to using the perfect pull-up compared to the chin-up or the pull-up. However, the researchers noticed a better biceps brachii recruitment with the chin-up and the perfect pull-up, which means that the supinated grip during a bar exercise activates this muscle (see the figure below).

 

  Why would there be a difference between the chin-up and the lat pulldown (supinated grip) in terms of biceps brachi recruitment? This difference can be explained by the consequence of the extent of torque generated in the elbow joint during these two movements. To give you a little background information, torque is produced (and expressed in Newton meters) in a joint or a pivotal point and it corresponds with the load (mass x acceleration) multiplied by the horizontal distance (in meters) between the pivot and load. For example, the two people we see in the figure below are in balance because their torque is equal: Person A is deploying a 1000 Nm torque (1000 N x 1m) and Person B is also deploying a 1000 Nm torque (500 N x 2m). If we take the two examples quoted above (the chin-up and the lat pulldown) and put them into the context of torque, we get the values presented in the figures below.       We see that the horizontal distance of the load handled during the chin up (the person’s body weight) is located far from the joint. This creates torque that is greater than the load handled during a lat pulldown with a supinated grip. In both cases, the load is placed above the joint during the movement, which deploys less torque. Summary To maximizer the recruitment of your biceps during arm training, opt for a combination of exercises. For example, you’ll get more out of your work out if you combine chin-ups and standing curls and forget about the supinated lat pulldown (since it has no muscular advantage over its various variations). You can use the lat pulldown to increase your or your clients’ motivation and vary the training tasks in your work out, instead of counting on it to favour the recruitment of a specific group of muscles.
Have a great work out!

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References

• • Lehman, GJ, Buchan DD, Lundy A, Myers, N & Nalborczyk A (2004) Variations in muscle activation levels during traditional latissimus dorsi weight training exercises: An experimental study. Dyn.Med. 3, 4.
  • Lusk SJ, Hale BD and Russell DM (2010) Grip width and forearm orientation effects on muscle activity during the lat pull-down. Journal of Strength and Conditioning Research. 27 (7):1895–1900.
  • Youdas JW, Amundson CL, Cicero KS, Hahn JJ, Harezlak DT, Hollman JH (2010) Surface electromyographic activation patterns and elbow joint motion during a pull-up, chin-up, or perfect-pullup™ rotational exercise. J Strength Cond Res. Dec; 24 (12):3404-14.