Chin-up


The chin-up is a strength training exercise. People frequently do this exercise with the intention of strengthening muscles such as the latissimus dorsi and biceps, which extend the shoulder and flex the elbow, respectively. In this maneuver, the palms are faced towards the body.
It is a form of pull-up in which the range of motion is established in relation to a person's chin.
In the 1970s and 1980s, the term chin-up not only included an overhand/pronated grip, but some authors used it as the default meaning of the term, with an underhand/supinated grip called a "reverse" grip. Even in the 2010s "chin-up" still includes palms-away lifting. The term "chin-up" is still regularly used to refer to pulling using an overhand-grip.

Etymology

A chin-up is named by bringing the chin up through space, specifically in relation to its position with the bar or other hand grips. This can be either touching the bar or by bringing the chin over the bar. This exercise is easier for males than females because of the male tendency to have stronger and larger biceps and a higher centre of gravity.
This is usually achieved most easily with vertical forearms that are close to the body. For most, bringing the chin this high is most easily achieved with a supinated grip. Due to this, the phrase "chin-up" has become associated with pulling with this type of grip. Some have delegated the term pull-up to refer to the pronated grip. In spite of this, many refer to pull-ups with a pronated grip also as chin-ups, and the supine grip is still regularly called a pull-up.
Some organizations such as the American Council on Exercise have adopted this new terminology, issuing statements such as: "a chin-up differs from a pull-up in that the puller's hands are facing towards him or her in a chin-up, and away in a pull-up." Organizations such as the United States Marine Corps, however, use the term pull-up interchangeably to refer to both the overhand and underhand grips.

Form

A chin-up has a variety of different forms.
The movement begins with the arms extended above the head, gripping a hold. It may be fixed, such as a chin-up bar or moving, such as gymnastic rings or rotating handles.
The body is pulled up, with the bar approaching or touching the upper chest. A chin-up is considered complete based on a variety of criteria in relation to where the chin should be in respect to the bar, or in respect to the hand grips.
The body is then lowered until the arms are straight but not in a lockout, and the exercise is generally repeated.
Like any pull-up, chin-ups can be performed with a kip, where the legs and back flop around to aid the exercise, or from a dead hang, where the body is kept still. Performing the chin-up correctly can be tricky with a supinated grip, because of the natural tendency to do most of the work with the elbow flexors rather than the shoulder extensors.
Initiating the pulling action with scapular depression may help avoid this problem. The exercise is most effective in stretching the working muscles when the body is lowered down to a full extension.

Muscles targeted

Chin-ups, like most pull-ups, target the latissimus dorsi muscle of the back as a shoulder extensor, scapular downward rotator and scapular depressor, in bringing the spine to the humerus. This is assisted by elbow flexors which bring the humerus to the forearm. Chin-ups, unlike pull-ups, also highly target the biceps. That is one of the main differences between pull-ups and chin-ups.
The lat's functions are also assisted, both by shoulder extensors, scapular downward rotators, and scapular depressors.
Pulling higher with a narrow grip puts the focus on extension rather than adduction of the shoulder.
If one leans back at the top of the movement, the focus is shifted somewhat towards scapular retraction and hyperextension.
The weight of the legs and pelvis are borne by spinal ligaments and various muscles that flex or extend the spine. If the pelvis is tilted anterior and the legs brought behind, the erector spinae bears more weight. If the pelvis is tilted posterior and the legs brought in front, the rectus abdominis bears more.

Variations

Specific training is needed in order to increase chin-ups performance.
The performance can be measured in various ways:
Various organizations like Guinness World Records maintain lists of world records for chin-ups and pull-ups. Both recordholders.org and Guinness World Records maintain that pull-ups use a pronated grip, while chin-ups use a supinated grip.

Chin-ups in fitness assessments

The chin-up exercise is used by uniformed services around the world to assess the physical fitness of its members. In order to be accepted into and remain in a particular service, a candidate may need to carry out a certain number of chin-ups to a prescribed technique. This number may vary with age and gender.
Chin-up bars are playground equipment that were once ubiquitous on children's playgrounds. They are still important in the adult equivalent of a playground, the Par course. A chin-up bar is simply a smooth horizontal metal bar, often a pipe, held solidly above ground by a wooden or metal frame. Typical installations include 2 or 3 different heights of bars for people of different heights. Chin up bars are also a part of a home gym setup. Types of chin-up bars include doorway-mounted, wall-mounted, ceiling-mounted and free-standing.