2023-11-14 18:53:33
There is no longer any doubt that practicing physical or sporting activity is an essential factor in good health, whether physical, psychological and social. However, whether you are an amateur athlete or a professional athlete, practicing a sport can expose you to the risk of injury.
This risk depends on various parameters, including the discipline practiced. If the number of injuries per 1000 hours of practice is relatively low in bodybuilding (0.24 to 1), the incidence of problems is greater in team sports: 8.1 in football, 9.1 in ice hockey or 12.6 in rugby.
Read more: Rugby World Cup: Why hamstring injuries are so common in the sport
Certainly, the number of injuries is higher in opposition sports due to contact between athletes. But when we consider non-contact injuries, that is, when the athlete injures themselves, workload appears to be a central factor in the occurrence of injuries.
But when faced with the same workload, not all athletes are equal. Genetics, in particular, play a role in the differences observed between individuals. Explanations
What is workload?
Workload is characterized by the volume, intensity and frequency of training. The increase in this load increases the risk of injury: for example, it is multiplied by 6.2 when footballers play two matches per week compared to just one.
To reduce the risk of injury, coaches carefully control the training load, which is characterized by the so-called “external” load and the so-called “internal” load. External load corresponds to the amount of work performed by the athlete while internal load reflects the internal responses induced by the external load. The same external workload, applied to different athletes, will generate different internal responses.
John Arano/Unsplash
This interindividual variability, in response to the same external load, makes it difficult to adequately program training loads. Better knowledge of individual factors would make it possible to better program training loads and thus limit the risk of injuries.
In addition to the training load, different parameters seem to be involved in this inter-individual variability: age, sex, psychological factors, recovery potential, training capacity and even genetics.
The importance of genetics
The proteins that make up our body and participate in our physiology are produced using the information contained in our genes. However, from one person to another, the same gene can be slightly different, presenting subtle variations in its sequence. Depending on the location of these variations, the quantity of proteins produced, or even their functioning, can be more or less modified.
These changes may impact individuals’ susceptibility to injury. Although research applied to muscle damage is in its infancy, work has shown that certain genetic variations help explain the variability in muscle damage observed following muscular exercise. (Yamin et al. 2008; Pimenta et al. 2012; Baumert et al. 2016).
In particular, it has been shown that, following exercise that induces muscle damage, people with certain genetic variations suffer greater damage and must observe longer recovery times. This is, for example, the case of the gene coding for ACE (angiotensin I converting enzyme).
The angiotensin gene exists in two forms (we speak of an “allele”): the I allele, or the D allele. Given that, in species that reproduce sexually, such as humans, each gene exists in two copies (one inherited from the mother, the other from the father), an athlete can therefore have various combinations of alleles depending on their inheritance:
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ACE II, if both alleles of the ACE gene are I;
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ACE ID, if one allele of each kind is present;
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ACE DD, if both alleles are D.
However, work has shown that individuals presenting one or more I alleles of the angiotensin gene, therefore people with ACE II or ACE ID genetic profiles, have an increased susceptibility to muscle damage, compared to individuals with the ACE DD genotype. , which lacks the I allele. The ACE DD genotype therefore confers protection once morest muscle damage. It must be emphasized, however, that the fact of being protected does not mean that the athlete cannot be injured, but only that the risk of injury is lower.
Our genome is made up of around 21,000 different genes, each of which can have small variations. It is likely that the combination of our genes explains our susceptibility to injury. Thus, it has been demonstrated that the combination of certain variations in the COL5A1, IL1B and IL6 genes is associated with an increased risk of injury to the anterior cruciate ligament in a population of men.
There are still many unknowns in this area of research. However, it is possible that in the long term, each individual might be characterized by a susceptibility score to muscle damage. This approach should not be used as a selection criterion, but rather as a tool to best adapt the training of athletes and allow them to maximize their sporting performance, while limiting their risk of injury.
I like biology
The genetic approach in the field of sport, although used by many athletes via parallel circuits, is not legal in France. The strict French regulations aim to protect privacy, guarantee the quality of tests and avoid potential abuses, such as the selection of athletes with specific genes.
It must, however, be emphasized that biological responses to exercise reflect the phenotype (the set of observable, apparent characteristics of an individual: eye color, anatomy, etc.) rather than the genotype (the set of genes). The phenotype results from the interaction between the environment and the genes.
It happens that certain genes present in the genome are not necessarily expressed. In other words, it is not because a protective gene is present in the genome that it will necessarily have effects, or the same effects in all people who possess it. A genetic analysis might highlight the presence of a protective gene without it having any effect in protecting the athlete from injuries.
Beyond genetic markers, other approaches provide information on the potential risk of injury. This is the case of blood biology, which consists of analyzing molecules present in the blood which provide information on given biological processes (also called “biological markers”). Currently under development, this approach might provide new indices for monitoring and individualizing the training load.
Jonathan Borba/Unsplash, FAL
Among them, let us cite for example the case of measuring the blood level of creatine kinase, a marker of muscle damage whose concentration in the blood increases following bodybuilding or endurance efforts, with great interindividual variability. This marker can be considered as a decision-making aid and its use is becoming more widespread in professional sports clubs.
A high level of creatine kinase is indeed an indicator of a weakened muscle and/or a sign of muscle damage. Its detection can prompt coaches to reduce the training load or decide not to play an athlete in order to avoid a muscle injury.
Various other biological markers reflecting sensitivity to muscle damage also exist, such as myoglobin or certain markers of the inflammatory response such as interleukin 6 or C-reactive protein. Future work will likely identify others.
In order to make the most of the contribution of biology, it will however be necessary to fully understand and understand the variations of the different parameters measured in order to select the appropriate parameters and use them wisely. But whatever the case, sports biology probably has a bright future ahead of it in helping coaches better prepare their athletes while reducing the risk of injury!
This article is published as part of the Science Festival (which takes place from October 6 to 16, 2023 in mainland France and from November 10 to 27, 2023 overseas and internationally), and of which The Conversation France is a partner . This new edition focuses on the theme “sport and science”. Find all the events in your region on the Fetedelascience.fr website.
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