Genetic factors influence the structural properties of the collagen within connective tissues, which affects tissue elasticity and joint mobility. Additionally, genetic predispositions can influence body composition and muscle length, further impacting flexibility. A 2016 meta-analysis explored the genetic and environmental influences on flexibility among other physical fitness components. The findings revealed a significant heritability estimate of 77% for flexibility.
COL5A1
The COL5A1 gene is a crucial gene that encodes for type V collagen, one of the minor collagen components found in connective tissues throughout the human body. This collagen is especially significant in the skin, tendons, and bone. It plays a foundational role in forming and maintaining these tissues. Researchers have studied the variations in the COL5A1 gene for their potential influence on flexibility, joint mobility, and risks associated with specific sports injuries, like tendon and ligament ruptures.
A 2015 study explored the link between the COL5A1 gene polymorphism and range of motion, specifically through the passive straight leg raise (SLR) and whole body joint laxity (WBJL). The study involved 177 participants (109 males and 68 females) in an Asian population of Korean and Japanese college students. Their COL5A1 rs12722 polymorphism was genotyped among the participants. Findings revealed that this specific COL5A1 gene polymorphism is associated with an increased range of motion in the SLR test among the Asian population studied, indicating its potential impact on flexibility and joint movement.
ACTN3
The ACTN3 gene encodes the protein α-actinin-3. It is highly expressed in fast-twitch muscle fibers crucial for high-speed and power activities. This gene is famous for its R577X (rs1815739 (C>T), polymorphism, which directly affects the presence or absence of α-actinin-3 due to genetic variation and thus influences muscle function and athletic performance.
A 2017 study investigated the link between the same ACTN3 R577X polymorphism and flexibility and muscular strength and power in two separate cohorts from the Tokyo metropolitan area. Cohort 1 included 208 men and 568 women aged 23-88, and Cohort 2 consisted of 529 men and 728 women aged 23-87. All participants underwent testing for grip strength and sit-and-reach flexibility. When they pooled the data from both cohorts, the results indicated that the RR genotype (rs1815739 CC) was significantly associated with lower flexibility when compared to the RX and XX genotypes.
You may also like: Decoding the Genetics of Power and Endurance
Other Markers
In 2020, researchers conducted a large genome-wide association study (GWAS) on 796 European athletes and analyzed 476,728 SNPs. The objective was to explore the genetic factors influencing elite endurance athletic performance, including traits such as flexibility. A significant finding from the meta-analysis was the association of SNP rs1052373 in the Myosin Binding Protein C3 (MYBPC3) gene (known for its role in cardiac hypertrophic myopathy) with the status of endurance athletes. European athletes who were homozygous for the G-allele of rs1052373 had an odds ratio of 2.2 for being elite endurance athletes.
A 2023 GWAS focused on the genetic factors that may influence athletic performance. It focused on sports that require excellent coordination and agility. A notable discovery was identifying a genome-wide significant association with the SNP rs117047321, confirmed in a replication study. The CG genotype of this SNP, found exclusively in Asia, particularly among East Asians, was associated with longer average movement times when compared to the CC genotype. This SNP is in the MYO5B gene, a gene highly expressed in critical tissues such as the brain, heart, and muscles, indicating its potential role in human energy metabolism.
While genetics set a baseline, environmental factors like activity level and training are vital in determining flexibility as described further in this article.