The COL5A1 gene is associated with the synthesis of type V collagen, a key constituent of ligaments and tendons. Specific alleles of this gene are known to either increase or decrease the risk of injury.
A study conducted on people with Achilles tendinopathy showed that those with the CC genotype of COL5A1 were associated with a lowered risk of developing Achilles tendinopathy compared to people with the T variant. Similar results were seen among people with anterior cruciate ligament injuries, again people with the CC genotype were found in lower numbers in a group of people with an ACL injury.
In terms of flexibility, people with the T variant of the gene are associated with a lower range of motion, implying that they could be less flexible. People with the TT genotype have tendons that are stiffer than those with the CC genotype. The stiff tendons and the lowered range of motion could be the reason behind the potential increase in risk of injury among people with the TT genotype.
Stiffer Achilles tendons have an increased capacity to store and return energy thus providing an advantage in endurance running. This would mean that people with stiff achilles tendons would require lower amount of energy for every step, making such runners more efficient. This is what makes people with the T variant (less flexible) better suited for long distance running events. Support for this theory comes from an ultra-marathon running study conducted in 2011. The study reported that people with the T variant had stiffer tendons but finished significantly faster than people with the C variant of the gene Col5A1.
In a study conducted on people with self reported history of exercise associated muscle cramping, people with the C variant were shown to be over-represented among people with no history of exercise associated muscle fatigue.
“Nutrigenetics, fitness genetics, health genetics are all nascent but rapidly growing areas within human genetics. The information provided herein is based on preliminary scientific studies and it is to be read and understood in that context.”