The human back, a complex structure of muscles and bones, plays a crucial role in our daily lives. It supports the weight of the upper body, enables us to stand upright, twist, and bend, and protects the spinal cord. One of the key components of the back is the latissimus dorsi, often referred to as the "lats". Let's explain the intricacies of the back muscles, specifically focusing on the lats, their function, and their importance in physical culture and health.
The latissimus dorsi, the largest muscle in the upper body, extends from the middle to the upper area of the back. It's responsible for giving the back its width and contributes significantly to the typical "V" shape associated with an ideal male physique. However, the lats are not the only muscles that shape our back. Other muscles like the teres major and minor, rhomboids, and trapezius also play a pivotal role in defining the thickness or depth of the back.
The lats are indispensable for the opening of the clavicles and the adduction and elevation of the scapulae. They are responsible for extension, adduction, transverse extension, flexion from an extended position, and internal rotation of the shoulder joint. They also play a synergistic role in extension and lateral flexion of the lumbar spine.
Located in the back, the latissimus dorsi is a flat muscle that extends to the side, behind the arm, and is partially covered by the trapezius near the midline. It attaches to the spinous processes of the vertebrae and the small tubercle of the head of the humerus. The number of dorsal vertebrae to which it is attached can vary, and the muscle fibers may or may not reach the iliac crest.
The latissimus dorsi is innervated by the sixth, seventh, and eighth cervical nerves via the thoracodorsal (long scapular) nerve. Electromyography suggests that it is made up of six groups of muscle fibers that can be coordinated independently by the central nervous system.
The latissimus dorsi assists in arm depression, adducts, extends, and internally rotates the shoulder. When the arms are in a fixed position extended above the head, the lat pulls the trunk upward and forward. It plays a synergistic role in the extension and lateral flexion of the lumbar spine and behaves as a muscle of forced expiration and also as an accessory of inspiration.
Most exercises for the lats simultaneously recruit the teres major, the posterior fibers of the deltoid, the long head of the triceps brachii, as well as numerous other stabilizing muscles. Complex exercises for the lats typically involve elbow flexion and tend to recruit the biceps brachii, brachialis, and brachioradialis.
The back is among the most stimulating muscles to train in the gym. Its development in width is determined by the skeletal system, while the thickness is represented by the volume capacity of the ribcage. Back training involves high fatigue, both on an energetic-muscular and neuronal level. Therefore, it's crucial to apply the general rules of the hypertrophic stimulus, including high Time Under Tension (TUT), high intensity, good concentration of lactic acid, incomplete recoveries, and muscle exhaustion.
The power, size, and strength of the lats can be trained with many different exercises, including vertical pulling movements like pull-downs and pull-ups, horizontal pulling movements like bent-over row and T-bar row, shoulder extension movements with straight arms like straight-arm lat pulldown and pull-over, and deadlifts.
The latissimus dorsi has been shown to be involved in chronic shoulder and back pain. Since the lats connect the spine to the humerus, dorsal tension can manifest as suboptimal function of the shoulder joint, leading to chronic pain or tendonitis.
Understanding the role, anatomy, biomechanics, and importance of the latissimus dorsi in training and health can significantly enhance our appreciation for this crucial muscle group. This knowledge is not only beneficial for athletes and fitness enthusiasts but also for anyone interested in understanding the human body better.