Long Bicep vs Short Bicep: Genetics Explained

published by: Debbie Luna
Last Updated:
November 12, 2022

Bicep length has been a widely discussed topic in the bodybuilding community because of the popularity of upper arm exercises and their contribution to better physique. The type of bicep an individual has, whether short or long, carries with it certain pros and cons. However, this is a factor that cannot be altered as bicep length is inherently hereditary.

The main genetic factor that contributes to a short or long bicep is the muscle-to-tendon ratio which is also known as muscle insertion. In general, this concept shows that a genetically long tendon and short muscle belly translates to a short bicep while a short tendon and a long muscle belly translates to a long bicep. Although other hereditary factors, such as limb length, may seem to contribute to the physical appearance of biceps, they do not influence actual bicep length.

Working out and building the biceps brachii muscle require an understanding of the specific type of bicep length an individual possesses as this helps in optimizing workout routines. Learning about the main genetic determinant of bicep length and the pros and cons of a short and long bicep also allows the individual to manage their expectations in terms of physical appearance and other attributes.

The Biceps Brachii Muscle

The biceps brachii muscle is a muscle of the upper limb that has two heads, a short and a long head that originates from the coracoid process of the scapula and the supraglenoid tubercle, respectively. Its name is derived from its two heads which merge into one distal body and inserts into the radial tuberosity and forearm fascia via the bicipital aponeurosis.

The biceps brachii is a two-jointed muscle that acts both on the shoulder and the elbow. The primary action of the biceps brachii is elbow flexion and forearm supination, but it also assists in shoulder flexion.

In building the biceps brachii, the focus is usually on attaining a bicep peak which is known as the mountain-like appearance of the muscle. Of the two heads of the biceps brachii, it is the long head that contributes to the bicep peak as it is the part that "bunches up" when the elbow is flexed.

Understanding the Genetics of Bicep Length

Having a long or short bicep largely depends on genetics. This means that an individual is naturally born with a specific bicep length, thus the physical appearance or aesthetic that one would want to achieve might not be feasible no matter the exercise they apply. Nutrition can be applied genetically however it does not affect musculature.

The main genetic factor that determines whether an individual has a short or long bicep is the muscle-to-tendon ratio or the point of muscle insertion. While limb length may seem to contribute to how short or long biceps appear, it does not influence actual bicep length.

Muscle-to-Tendon Ratio or Muscle Insertion

The bicep, like all other muscles, is composed of muscle bellies and tendons. The muscle belly is the main part of the muscle which is what increases in size during bodybuilding. The tendon, on the other hand, is the part that connects or attaches the muscle to the bone, thus allowing movement.

The muscle-to-tendon ratio basically shows that a long bicep is commonly determined by a long muscle belly and a short tendon while a short bicep is said to have a short muscle belly and long tendon. This concept is also referred to as "muscle insertion" which is often confused as the insertion of the tendon to the bone. In the context of bodybuilding and muscle length, the point of muscle insertion is basically the point where the tendon and muscle fibers meet. A low point of muscle insertion means a long bicep while a high muscle insertion refers to a short bicep.

There are different ways to determine an individual's bicep length. One method is to use the fingers to measure the length of the tendon while the elbow is flexed at a 90-degree angle. If more than two fingers fit in the space between the end of the contracted bicep muscle belly and the forearm, then that is considered a short bicep. A long bicep is one where two fingers or less fit in the space described.

Limb Length

Limb length, like bicep length, is genetically determined but these two concepts do not have a clear cut relationship. Although people with short limbs may appear to have short biceps while those with long limbs may appear to have long biceps, this is not the case.

Individuals, whether possessing short or long limbs, may have varying bicep length. Furthermore, bicep length does not determine the length of all other muscles in the body. This means that having a long bicep does not necessarily point to having long calves as well.

Comparison Between Long and Short Bicep

Having a short or long biceps brachii has its advantages and disadvantages. If the end goal for working out is to have big, full-looking arms even at rest, having long biceps is ideal. On the other hand, a higher bicep peak may be more attainable if an individual has short biceps. The drawback with short biceps is that although the muscle is more pronounced when flexed, it may seem smaller and the arm may look less full when it is relaxed. 

In terms of strength and power production, there seems to be no difference in force generation between the two. The capacity to produce force is dependent on the cross-sectional area of a muscle rather than its length. In order to increase strength, the muscle must have more protein filaments and cross-bridges, which are present in a muscle with a larger cross-sectional area. Because a large muscle width is attainable by both short and long biceps, both types are capable of producing the same strength and power.

Final Thoughts

Bicep length is an inherently hereditary factor influenced by the genetic muscle-to-tendon ratio, and thus cannot be changed no matter what exercise an individual applies. While this means that the bicep is bound to look a certain way depending on whether it is short or long, bicep length is not a hindrance to growing defined and muscular arms. Furthermore, each type of bicep length has its own advantages and disadvantages and cannot be claimed as superior to the other.


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Debbie (Deb) started powerlifting and Olympic lifting in High School as part of her track team's programming; She continues to train in order to remain athletic. Inspire US allows Deb to share information related to training, lifting, biomechanics, and more.
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