MUSCLE OF THE MONTH – LATISSIMUS DORSI
In today’s blog we are looking at one of the largest muscles in the body, the latissimus dorsi.
The latissimus dorsi is a broad, flat muscle, the largest in the back. A personal trainer will often set exercises that use this muscle, such as lateral pull downs and bent over or seated rows.
ORIGINATION OF THE LATISSIMUS DORSI
The muscle originates from the lower back, from the spinous processes of the sacrum, the lumbar and the lower six thoracic vertebrae. It also originates from the inferior angle of the scapular – the lower point of the shoulder blade.
The latissimus dorsi then spans across the lateral side of the trunk and inserts on to the bicipital groove of the humerus, just below the shoulder joint.
HOW THE MUSCLE WORKS
The latissimus dorsi is a large, strong muscle that can take a significant amount of force and provide a lot of power, whether an individual is using it in a programme set by a personal trainer or simply during everyday life. It is used to extend and adduct the arm, as well as medially rotate the humerus.
EXERCISING THE LATISSIMUS DORSI
If a personal trainer is specifically looking to work a client’s latissimus dorsi muscle in a gym environment, they will design an exercise programme that includes lateral pull downs, bent over rows and seated rows.
In addition, it’s an important muscle when it comes to posture, as it forms the outer layer of the core muscles and affects the movement of the trunk. It can therefore come into play when a fitness instructor asks a client to carry out a back squat or a dead lift.
The latissimus dorsi helps with the extension of the trunk, keeping the back upright as the client performs an exercise. If the back isn’t upright, they risk going into trunk flexion, which will result in the vertebrae leaving the neutral position they should be in during these exercises.
THE DANGERS OF OVERWORKING AND FAILING TO STRETCH THE LATISSIMUS DORSI
A fitness instructor may often find they have clients who have overworked their latissimus dorsi in the quest for large back muscles. Also many people have a tendency not to stretch the latissimus dorsi sufficiently. Because the muscle’s two origin points are the pelvis and the scapula, either overworking or failing to stretch the muscle can cause hyperextension of the back, which can lead to the spinal abnormality, lordosis: an excessive curvature of the lumbar part of the spine.
So while it’s important to work the latissimus dorsi in closed-chain and open-chain exercises, it’s also important for a personal trainer to use traditional stretching methods with their clients, as well as, if needed, PNF stretching.
FUNCTIONAL USE OF THE LATISSIMUS DORSI
The latissimus dorsi is often called into play in everyday activities. These include someone using the banister to help pull themselves upstairs, to opening a heavy door or picking up bags from the floor. As it is such a major muscle with so many uses, it’s important that the latissimus dorsi is working at its optimal length and strength.