Muscle Fiber Type-Specific Training: The Lats!

I’m currently doing a Fitness-Tip Friday mini-series where I highlight the relatively small number of muscles that have a large majority of either fast-twitch or slow-twitch muscle fibers (most muscles have a fairly even split), and therefore need to be worked accordingly in order to get the best results from your training!

Last week I briefly went over the differences between the three muscle fiber types (I, IIa, and IIb) and the research regarding the effectiveness of working muscles based on their fiber types, and then discussed how the upper trapezius is one of the only back muscles that has a high percentage of Type II muscle fibers, and thus how to best train it! (Note: If you just subscribed and want to view that, a catalogue of all previous FTF tips is included in the All-Access Basic Membership)

There is, in fact, only ONE other back muscle that also has a high percentage of Type II fibers – and that muscle is the latissimus dorsi, aka the “lats”!

The lats are the widest muscles in the body and have many different origination points, and therefore perform a wide variety of different movements which I went over in-depth in this recent YouTube video. Since it’s a fast-twitch dominant muscle, you can work any of those movements using explosive movements and/or heavy weight in order to maximize the exercise’s effectiveness.

However, here’s my personal favorite fast-twitch lat exercise, which integrates both explosive contractions and heavy weight, and does so at an angle that is as lat-specific as it gets! (Plus it’s just plain fun to do!):

As a final interesting note, the lat muscle fiber type percentage actually differs by gender to a greater degree than most muscles. As determined by this study, males on average have a 71% majority of Type II fibers (combining IIa and IIb), which females on average have a 64% Type II majority. 

Application: Make sure to frequently work your lats with heavy and explosive movements to maximize growth!!

Relevant Research Article(s):
      1) Myosin Isoforms and Contractile Properties of Single Fibers of Human Latissimus Dorsi Muscle

      2) Resistance exercise elicits fiber type-specific changes

Related Dr. Gains YouTube Video(s):         
      1) 5 Key Lat Training Secrets! EVERYTHING You DIDN’T KNOW About Working the Latissimus Dorsi [5MM Lats]