Swimming Anatomy

The erector spinae muscle group is composed of a series of muscles separated into three columns that run vertically along the spine. The iliocostalis forms the most lateral column, the longissimus forms the middle column, and the spinalis forms the most medial column. The columns share a common origin spanning the posterior iliac crest, the posterior sacrum, and a portion of the lumbar vertebra. The superior attachments are variable, depending on the column. When the erector spinae groups on each side of the spine contract in unison, extension of the trunk occurs. When only one muscle group contracts, lateral flexion (side bending) and rotation of the trunk occur to the side of the muscle group that is contracting. The gluteus maximus and the hamstring muscle group (biceps femoris, semitendinosus, and semimembranosus) are commonly activated in unison with the erector spinae because they extend the hip, a movement that commonly takes place in conjunction with extension of the spine; their anatomy will be discussed in chapter 7.

Figure 6.1 Back muscles.

Although the pectoralis major and the latissimus dorsi are both defined as humeral propellers and together produce most of the upper-extremity propulsive forces responsible for driving a swimmer through the water, of the two, the latissimus dorsi is the prime mover. During freestyle, butterfly, and breaststroke, the latissimus dorsi begins contributing shortly after hand entry at the initiation of the propulsive portion of the pulling phase. During backstroke, no delay occurs in the activation of the latissimus dorsi. In all four stokes the latissimus dorsi remains active from its point of recruitment during the propulsive phase until the initiation of the recovery phase. In butterfly, it contributes to the initiation of the recovery phase. For every exercise that primarily targets the lats, extra emphasis should be placed on pinching the shoulder blades together in the ending position. Doing this increases the recruitment of the musculature that stabilizes the shoulder blades, further increasing the benefit of the exercise.

The erector spinae muscle group is extremely important in maintaining proper horizontal body alignment in the water, especially during backstroke. Whenever a swimmer has difficulty holding a tight streamline in the water or allows the hips to drop while swimming backstroke, the erector spinae should be near the top of the list of suspected areas of weakness. The erector spinae muscle group produces the extension of the spine that takes place with the undulating body movements performed with underwater dolphin kicking, butterfly, and breaststroke. The erector spinae muscle group also plays a vital role in the starting motion of all four strokes. During starts performed from the blocks, it is one of the primary muscle groups responsible for creating the streamlined body position. During backstroke starts, contraction of the erector spinae leads to the arching motion that allows the swimmer to get off the wall and into the water quickly.

Chin-Up

Execution

1. Grasp the bar with an underhand grip, with the palms facing your body. Your hands should be slightly wider than shoulder-width apart. Hold your knees in a bent position and cross one foot over the other.

2. From a hanging position pull your body upward, focusing on bringing your chest to the bar.

3. Pause at the top of the movement and then slowly lower to a hanging position.

Muscles Involved

Primary:Latissimus dorsi

Secondary:Biceps brachii, brachialis, lower trapezius, rhomboid major, rhomboid minor, teres major

Swimming Focus

Chin-ups are a great addition to any dryland program because they can be done wherever a chin-up or pull-up bar is available. In comparison with the hand positioning for pull-ups, the hand placement for chin-ups emphasizes the elbow flexors (biceps brachii and brachialis). By targeting both the latissimus dorsi and the elbow flexors, this exercise benefits all swimmers by strengthening the pulling phase of their strokes. Because chin-ups are generally a challenging exercise for most swimmers, they are useful for building mental toughness. To help you reach your goal number of repetitions, a partner can assist by supporting your feet.

Make sure that your body movements are slow and controlled during the exercise. Excessive jerking and swinging of the legs is a form of cheating.

SAFETY TIP