How Do Genes Influence Tendon Strength?

Tendons are made of fibrous connective tissues that attach muscles to bones. They are present at each end of a muscle. The largest, and most commonly known tendon, is the Achilles Tendon, which attaches the calf muscle to the heel bone. Tendons and ligaments give mobility, flexibility, and stability to our body joints and are required to work in tandem at all times.

Tendons are made up of dense fibers of collagen. The basic unit of a tendon is the primary collagen fibers, which are collagen fibrils. Collagen fibers are resistant to tearing but are not very stretchy.

Tendons also have fewer blood vessels compared to muscles and are thus more injury-prone. Added to this, any injury to tendons requires a much longer recovery time.

Tendons play an important role in transferring the contraction force produced by the muscles to the bone they hold. They help keep the joints stable. When muscles are put into action, the tendons help absorb some of that impact.

The tendon size determines the actual and potential muscle size. People with shorter tendon lengths and longer biceps have a better ability to build muscle mass than those with longer tendon sizes. Shorter tendons are associated with successful bodybuilders.

Importance of Strengthening Your Tendons

Strong tendons are necessary for?withstanding stresses generated due to muscular contraction. During weight lifting, it’s just not the muscles that take the impact -?your tendons take some of that impact, too. This demands an adaptive response. When properly developed, a tendon has good elasticity and is?strong and capable of great power. As seen before, tendons receive a lesser blood supply and thus take a lot more time to respond to training than muscles.

Exercise to strengthen your tendons can?help prevent tendon injuries like tendonitis.

How Does Genetics Influence Tendon Strength

COL1A1?and Tendon Strength

COL1A1, also called collagen type 1 alpha 1 chain, is a gene that encodes a part of type 1 collagen. Type 1 collagen is the most abundant form of collagen in the body. Collagen synthesis begins as rope-like procollagen molecules, and each molecule is made up of three chains – two pro-α(I) chains and one pro-α(II) chain. Cross-linking between the collagen fibers is responsible for strengthening these fibers and the structures they give rise to.

The?COL1A1?gene is located on chromosome 17, and a particular variant of this gene is associated with increased susceptibility to sports-related tendon and ligament injuries.

rs1800012 of?COL1A1?Gene and Tendon Strength

A single nucleotide polymorphism (SNP) rs1800012 in the?COL1A1?gene has been associated with tendon and ligament injuries like ACL injuries, Achilles tendon injuries, shoulder dislocations, and tennis elbow.?People with the TT type have a reduced risk of sports injuries involving tendons and ligaments. Even though it’s rare, the TT type is found to play a protective role.

COL5A1?and Tendon Strength

COL5A1?or Collagen Type V Alpha 1 gene?encodes a component of type V collagen. The?COL5A1?gene synthesizes the pro-α1(V) chain of collagen V. Type V collagen is associated with the regulation of the diameter or width of the fibrils. Studies have shown that type V collagen controls the assembly of the other types of collagen into fibrils in various tissues.

The?COL5A1?gene is located on the q arm of chromosome 9 and is associated with Carpal Tunnel Syndrome and Ehler Danlos Syndrome. A particular variant of this gene is associated with soft tissue injuries.

rs12722 of?COL5A1?Gene and Tendon Strength

rs12722 is an SNP in the?COL5A1?gene. It is associated with Achilles tendon pathology, Achilles tendinopathy, tennis elbow, and anterior cruciate ligament rupture. According to a study, people with the?CC type of rs12722 had a significantly decreased risk for Achilles tendinopathy?than those with CT and TT.?Individuals with TT are at a higher risk of Achilles tendon pathology, anterior cruciate ligament injuries, and tennis elbow.

Some other genes that influence tendon strength include?GDF5?and?MMP3.

Non-genetic Factors That Influence Tendon Strength

The factors that affect the physical properties of collagen also influence the tendon strength

• Age: As you age, the?stiffness of type 1 collagen increases. The amount of total collagen content also decreases.
• Diabetes: According to a study,?experimentally induced diabetes increased tendon stiffness in rats. There was no change upon administering insulin.
• Physical training: Training increases tensile strength in tendons and the ligament-bone interface.
• Pregnancy and postpartum: According to a study,?pregnant rats showed a marked decrease in tensile strength?as compared with standard, nonpregnant female rats.

Recommendations to Improve Tendon Strength

Many exercises and workouts can help you enhance your tendon strength. The idea behind these exercises is to use short-range movements that allow heavier weight lifting. This gradually improves tendon strength. Some particularly helpful exercises are:

• Eccentric exercises
• Partial reps
• Stretching: including a full range of motion–pectoral stretch, calf stretch, front squat.
• Intensity training
• Volume increasing exercises
• Explosive isometrics

Tendons are made up of collagen, and therefore, collagen boosting can help strengthen your tendons.

Some nutrients like vitamin A, B vitamins, vitamin C, calcium, and magnesium help collagen strengthen. Protein-rich food also helps strengthen tendons as collagen is, after all, a protein.

The following foods can be included as part of your daily diet:

1. Nuts like almonds, peanuts, walnuts, cashews, pecans, hazelnuts
2. Seeds like sunflower seeds, chia seeds, flax seeds, pumpkin seeds
3. Citrus fruits like oranges, grapefruits, guava
4. Berries
5. Leafy greens like spinach and kale
6. Soy and soy products like soy milk, tofu, tempeh
7. Chickpeas
8. Salmon
9. Chicken
10. Potatoes
11. Beans and other legumes
12. Bananas

Summary

1. Tendons are fibrous tissues primarily made of collagen. It connects bones to muscles. The Achilles tendon is the largest tendon that connects the calf muscle to the heel bone.
2. Tendons are ligaments that are crucial for mobility. Strong tendons also help with injury prevention.
3. Certain genes that are responsible for collagen production also affect tendon strength. rs12722 is an SNP in the?COL5A1?gene that is associated with tendon injuries. People with the CC type have a decreased risk for injuries like ACL tear and Achilles tendinopathy. The TT type, on the other hand, is associated with an increased risk.
4. Other factors that influence tensile strength include age, levels of physical activity, conditions like diabetes, and pregnancy.
5. Short-range motion exercises with heavier weights are recommended to improve your tendon strength. Since tendons are made of collagen, collagen-boosting foods like nuts, seeds, salmon, bananas, and potatoes can also help strengthen your tendons.

Reference

• https://medlineplus.gov/genetics/gene/col1a1/
• https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5432363/
• https://medlineplus.gov/genetics/gene/col5a1/
• https://sportsmedicine-open.springeropen.com/articles/10.1186/s40798-018-0161-0
• https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5880610/
• https://link.springer.com/chapter/10.1007/978-1-4684-9042-8_54
• https://www.surgjournal.com/article/0039-6060(52)90300-0/fulltext

First appeared in https://www.xcode.life/genes-and-fitness/how-genes-influence-tendon-strength/