What factors are involved in hamstrings injury?
Hamstrings injury is the most frequent muscle injury in sports that require high speeds, such as football, rugby or American football.
In elite football, there is a fine line between success and failure. Monitoring and quantifying the plethora of internal and external factors associated with performance allows us to better understand training adaptations and, based on these, make adjustments of the players’ condition. By positively correlating with the risk of injury, workload control is a fundamental process for optimizing performance. Workload is usually classified as external or internal, with external workload being the work done by the athlete (e.g. distance travelled, number of accelerations), and internal workload being the physiological response to that work (e.g. EPR, heart rate, lactate concentration, body temperature).
Technological progress has made it possible to use new tools that help to better understand the body’s responses when exercising. In this sense, metabolomics – a relatively young branch of the omic sciences – consists in the study of the metabolome, which comprises the set of metabolites that are generated during cell metabolism. The expression of genes or factors such as diet, exercise, stress, the menstrual cycle or circadian rhythms modulates the metabolome. Metabolomics can, therefore, be considered a very sensitive measure of an organism’s phenotype. Any alteration that occurs in the DNA, RNA or proteome, can cause significant changes in the concentration of metabolites, reflecting how the metabolism is working in an organ or a living being and therefore can act as an indicator of their health condition. Through metabolomic analysis, we can identify biomarkers for the prevention, diagnosis, and prognosis of diseases such as Alzheimer’s, diabetes, cardiovascular disease or cancer.
In the context of sports physiology, most of the metabolomic studies carried out have been performed in plasma or serum. However, urine offers significant advantages over other biofluids, this is due to it being easily obtained, painlessly, and non-invasively. However, the technique is complicated and expensive, so, as stated by Guillermo Quintas, from the Health and Biomedicine Unit of the Leitat Technological Center and author of several scientific articles on metabolomics, the objective must be twofold: “try to identify and describe metabolic alterations with utility for the follow-up of elite athletes, and to be able to develop simplified models that can be transferred to routine practice in fast and less expensive equipment, without losing information”. Despite being considered a waste product, analysis of the composition of urine can provide so much information that even Hippocrates, the so-called father of modern medicine, used it for diagnostic purposes as early as the 5th and 4th centuries BC.
On this basis, members of the F.C. Barcelona Medical Department and the Barça Innovation Hub have just published a scientific article in which they study the association between external load and changes in the urinary metabolome over the course of a season, in order to evaluate the use of metabolomics as an indicator of the risk of muscle injury in professional football players (1). The application of metabolomics to the world of sport could be very interesting. Thus, as indicated by Quintas, the first author of the work,
“metabolomics will allow us to identify markers that describe the adaptation of the athlete to training in a personalized way. We have already been able to observe adaptations in metabolic pathways associated with acute and chronic external load in professional athletes. In addition, metabolomics has all the potential to analyse or detect important stress situations throughout the season, changes in diet, alterations in the microbiota, and even the interaction between these effects”.
Researchers collected the first-morning urine, 5 times throughout the season: during the pre-season and at 3, 5, 8 and 10 months within competition (in all cases after a day of rest). Meanwhile, external load data was collected using monitoring devices or EPTS (WIMU PRO), to record player and ball positions. For each player, the main external load variables were analysed, such as distance, distance travelled at high metabolic demand, accelerations or high-intensity actions, among others.
The analysis of the urine samples allowed detecting changes in the metabolism that were related to the external load. Those associated with external load included metabolites of steroid hormones or metabolites of tyrosine and tryptophan. In addition, using a mathematical model, they saw that those who were injured the most were also those who deviated the most in the projection made by the model. In this way, this analysis can help to estimate causalities between the variables obtained from the study of the metabolome and the workload.
These results indicate that external burden is associated with an adaptation of metabolic pathways, so metabolomics offers enormous opportunities to improve the understanding of human performance and exercise adaptations. In fact, Bongiovanni and colleagues suggest that metabolomics applied to sport, or sportomics as they define it, could be part of a new revolution in this field (2). In this sense, Quintas concludes that “we have observed metabolic adaptations associated with acute and chronic external load over a season. It is also known that the lack of adaptation to physical stress induces changes in e.g. the level of oxidative stress that results in a change in the metabolic profile. It is, therefore, reasonable to assume that the analysis of the metabolome will provide additional information to detect states of fatigue or poor adaptation. However, the risk of injury is multifactorial. The information provided by the metabolomics should be integrated and analysed together with the rest of the information collected from the athlete throughout the season”. In football, where even the smallest detail can draw the fine line between success and failure, any additional data – e.g., analysis of the urinary metabolome – could make a difference.
An article published in The Orthopaedic Journal of Sports Medicine —in which members of the club’s medical services participated— now suggests to consider the detailed structure of the area affected, and treating the extracellular matrix as an essential player in the prognosis of the injury.