Latissimus dorsi

The latissimus dorsi is a large back muscle with three main regions (thoracic, lumbar, and pelvic) that have unique origins at different points along the spine but the same insertion on the humerus of the upper arm. Fortunately, there are valuable research studies that allow us to understand the best ways to train each region.

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#1. Sagittal plane internal moment arm lengths

The three regions of the latissimus dorsi have different internal moment arm lengths from one another. According to the principle of neuromechanical matching, this means that the regions contribute differently to different exercises and movements. The superior (thoracic) region of the latissimus dorsi has the best leverage of the regions for shoulder extension. Its leverage is maximal at relatively short muscle lengths, suggesting that it will be best trained with narrow-grip rows rather than close-grip pull-downs.

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Indeed, in agreement with the internal moment arm lengths, the latissimus dorsi is more strongly activated at lower levels of shoulder elevation in sagittal plane pullover exercises.

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Although some fitness influencers dislike the idea that the latissimus dorsi has distinctive functional regions, muscle activation data support the fact that more of the upper (thoracic) region muscle fibers are activated in the sagittal plane.

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#2. Frontal plane internal moment arm lengths

The inferior (pelvic) and middle (lumbar) regions have the best leverage for shoulder adduction. Again, their leverage is maximal at short-to-moderate muscle lengths, suggesting that these regions will be best trained with wide-grip pull-downs where the resistance profile allows peak effort to occur closer to the end of the concentric phase.

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Indeed, muscle activation studies confirm that the latissimus dorsi is most strongly activated at lower levels of shoulder elevation in the frontal plane (as well as in the sagittal plane).

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Again, while some fitness influencers dislike the idea that the latissimus dorsi has distinctive functional regions, muscle activation data support the fact that more of the middle (lumbar) region muscle fibers are activated in the frontal plane.

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#3. Pullover exercise variations

Although pullover exercises allow the shoulder muscles to work without the biceps brachii also participating, the main disadvantage of this sagittal plane exercise is that the peak effort tends to be produced in the stretched position, where the latissimus dorsi has poor leverage. As a result, we tend to see greater involvement of the (costal) pectoralis major and the long head of the triceps brachii in comparison with the latissimus dorsi.

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#4. Rowing exercise variations

While the bent over barbell row is popular because it allows a large amount of weight to be used, this weight does not necessarily translate to an effective stimulus for the latissimus. Indeed, the inverted row is a superior latissimus dorsi exercise because it allows a greater focus on this area of the back, while the bent over row requires a great deal of support from the lumbar erectors, thereby focusing the exercise more on that area. 

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Similar observations have been made when comparing the seated row and lat pull-down with the bent over row.  Due to the greater involvement of muscles lower down on the back (in this case, the middle and lower trapezius), the bent over row does not activate the latissimus dorsi as effectively as the lat pull-down or the seated row. Overall, this suggested that seated rows, inverted rows (and chest-supported rows) the best rowing options for training the latissimus dorsi, while the bent over row is an inferior choice.

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#5. Stretch-mediated hypertrophy

The latissimus dorsi muscle regions have sarcomeres that appear to work mainly on the plateau of the length-tension relationship. Consequently, its chances of achieving the passive mechanical tension necessary to produce sarcomerogenesis are small. Moreover, since the muscle is difficult to activate in the stretched position (especially in the sagittal plane), there are few exercises that would allow any passive mechanical tension to be generated anyway.

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#6. Recovery capacity

The latissimus dorsi recovers more quickly than some muscles of the upper body that are famous for recovering slowly after a workout (the triceps brachii, the pectoralis major, and the biceps brachii) but more slowly than many muscles of the lower body (the quadriceps and calves). This suggests that optimal training frequency for a given level of workout volume will be higher than for pressing workouts but lower than for lower body workouts.

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The latissimus dorsi likely recovers faster than the triceps brachii, the pectoralis major, and the biceps brachii because these muscles contain a higher proportion of fast twitch muscle fibers. Fast twitch muscle fibers are more easily damaged after exercise because they have fewer mitochondria. Thus, they experience greater damage from the calpains (proteases) that are released in response to the influx of calcium ions during exercise.

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Conclusions

The latissimus dorsi is a large back muscle with three regions (thoracic, lumbar, and pelvic) that have unique origins at different points on the spine but the same insertion on the arm. The superior (thoracic) region of the latissimus dorsi has the best leverage of the regions for sagittal plane shoulder extension. Moreover, its relative leverage is maximal in the contracted position. Thus, it is best trained with close grip rows. The middle (lumbar) and inferior (pelvic) regions have the best leverage for frontal plane shoulder adduction. Moreover, their relative leverages are maximal in the short-to-mid-range position and so are best trained with wide grip lat pull-downs. While the inferior (pelvic) region does have some leverage for shoulder extension at high degrees of shoulder flexion, the pectoralis major and triceps brachii long head have better leverage, which makes most sagittal plane pullover exercise variations unsuitable for training the latissimus. Latissimus dorsi sarcomeres work predominantly on the plateau of the length-tension relationship, indicating that its muscle fibers will not readily experience stretch-mediated hypertrophy. In any event, since latissimus dorsi leverages are longest near to the contracted position and are extremely short in the stretched position, activating its muscle fibers so that they can experience the passive mechanical tension necessary to stimulate sarcomerogenesis is quite challenging.