Recent data on biomarkers and injury risk
Recent studies suggest that monitoring biochemical markers in the blood of athletes may help reduce the risk of injury and overtraining while supporting recovery. A systematic review of 28 studies involving professional team sports athletes showed that the trajectory of biomarkers reflects accumulated fatigue and recovery status and allows for more informed management of training load without compromising athletic performance. Tracking these parameters may support performance optimization and help reduce the risk of injury and overload.
Source: Soler-López et al., 2024 - Sensors, 24(21), 6862
Among the best-established biomarkers are:
- Muscle-damage enzymes, particularly creatine kinase (CK);
- Stress hormones, such as cortisol and testosterone;
- Markers of inflammation and oxidative stress.
Variations in these values are markedly more pronounced after competitions than after training sessions, and full recovery may take several days.
Source: Soler-López et al., 2024 - Sensors, 24(21), 6862
It is worth noting that muscle injuries represent a significant part of the injury profile in athletes. According to epidemiological studies of professional soccer, muscle injuries are among the most common injury types in this sport. This makes the early detection of muscle overload through blood analysis especially relevant. The economic impact can also be considerable: across professional leagues, injuries can represent a substantial burden over the course of a season.
Source: Ekstrand et al., 2011 - British Journal of Sports Medicine, 45(7), 553-558
For this reason, clubs and sports organizations increasingly turn to biochemical monitoring programs to protect both athletes' health and their financial investments.
Markers of muscle damage: CK, AST, LDH, and other parameters
Creatine kinase (CK) is one of the most widely used indicators for assessing muscle damage and fatigue. It is released from muscle cells during intense physical activity and reflects the degree of microtrauma to muscle fibers.
Source: Cadegiani et al., 2018 - Sports, 6(1), 19
Elevated CK values after competition have been documented in numerous sports. For example, a three-day tournament led to a significant increase in CK values in basketball players. Likewise, a six-week intensive training phase produced a marked rise in CK in rugby players compared with baseline values.
Source: Cadegiani et al., 2018 - Sports, 6(1), 19
Coaches and sports medicine physicians use these values to assess physical load: a high CK value indicates greater muscle demand and a greater need for recovery. However, interpreting CK requires an individualized approach. Studies show that baseline values can vary considerably between athletes, as can the physiological response to the same training load.
Source: Cadegiani et al., 2018 - Sports, 6(1), 19
For this reason, it is recommended to first determine each athlete's individual baseline CK value through a series of resting measurements and then monitor deviations from that individual baseline. A CK value of 500 U/L may be normal for one athlete, while for another, whose usual value is 200 U/L, it may indicate excessive load or insufficient recovery.
In addition to CK, enzymes such as aspartate aminotransferase (AST) and lactate dehydrogenase (LDH) also deserve attention. Although they are traditionally regarded as liver enzymes, in sports medicine they also serve as complementary indicators of muscle damage.
Source: Kalinowski et al., 2022 - IJERPH, 19(14), 8580
According to sports biochemistry, AST activity in the blood can reflect muscle damage with a reliability comparable to that of CK and can also be used to assess training load. Furthermore, recent observations in elite athletes have shown that a complete panel of AST, LDH, CK, and creatinine can provide a more stable picture of recovery than CK alone.
Source: Kalinowski et al., 2022 - IJERPH, 19(14), 8580
AST, LDH, and creatinine also show lower interindividual variability, which makes them more reliable markers for monitoring the risk of overtraining when assessed in combination.
The isoenzyme CK-MB and alpha-hydroxybutyrate dehydrogenase (alpha-HBDH) also deserve mention. CK-MB is frequently associated with cardiac muscle damage, but in athletes, mild elevations may also reflect intense muscular stress or microtrauma. Alpha-HBDH belongs to the LDH family and can rise in cases of muscle damage. In one study, researchers simultaneously monitored CK, CK-MB, LDH, and alpha-HBDH in soccer players and confirmed their parallel increase after intense matches.
Source: Lin et al., 2017 - Journal of Basic and Clinical Physiology and Pharmacology
Although these markers are used less frequently in daily practice, they provide scientific confirmation of the extent and severity of muscle microtrauma in professional athletes.
Metabolic markers and other readiness indicators
In addition to muscle-damage enzymes, an athlete's biochemical profile includes several metabolic markers that are important for assessing physical readiness and physiological balance. Among them:
- Glucose (GLU): blood glucose level reflects the body's energy availability. A low value may indicate incomplete glycogen replenishment or signs of overtraining. Well-recovered athletes generally show normal fasting glucose, while athletes with chronic energy deficits may show deviations.
- Uric acid (UA): the end product of purine metabolism, it acts as a marker of the intensity of metabolic stress. An increase after prolonged effort may reflect accelerated breakdown of ATP and nucleic acids in active muscle tissue. Some studies link elevated uric acid to oxidative stress and low-grade inflammation, both associated with overtraining.
- Creatinine (CRE): a breakdown product of creatine phosphate, it is directly related to muscle mass and renal filtration. Athletes often show slightly elevated creatinine values due to their greater muscle volume. However, an abnormal increase above the athlete's individual baseline may indicate dehydration or excessive muscle catabolism. In elite sport, creatinine is frequently monitored alongside CK, AST, and LDH in recovery-monitoring panels. Source: Kalinowski et al., 2022 - IJERPH, 19(14), 8580
- Amylase (AMY): a digestive enzyme produced by the pancreas and salivary glands. In sports science, salivary amylase is frequently measured as a stress marker, since it correlates with activation of the sympathetic nervous system. Elevated amylase values, whether in saliva or serum, may indicate acute stress or dehydration.
- Electrolytes (K⁺, Na⁺, Cl⁻, CO₂): electrolyte balance is essential for neuromuscular function and the prevention of cramps. Potassium, sodium, and chloride reflect hydration status and nutritional balance. For example, sodium loss through sweat without sufficient replenishment increases the risk of cramps and may reduce endurance capacity.
- CO₂ content, that is, the total concentration of carbon dioxide or bicarbonate, indirectly reflects acid-base balance. A change in CO₂ may indicate lactate accumulation or metabolic acidosis under intense effort. Monitoring these electrolytes helps the medical team adjust hydration and nutrition strategies to prevent heat-related muscle problems.
Taken together, these biochemical markers can provide a broader picture of the athlete's physiological status. Objective variations in blood values often precede the clinical symptoms of fatigue and thus allow for early intervention - such as load reduction, additional recovery, or nutritional adjustments - before the risk of injury or overload increases.
How clubs implement biomarker monitoring
In recent years, biochemical monitoring has become a common practice among elite sports teams and performance-oriented sports centers. Studies conducted in collaboration with professional clubs illustrate its practical value and potential utility.
- Soccer: at a professional Brazilian club, CK values were monitored on the second day after each match across four consecutive seasons. A total of 1,656 samples were analyzed. The results showed that CK values were consistently higher in matches followed by muscle injuries. However, CK alone was not sufficient to reliably predict future injuries: sensitivity was around 56% and specificity around 55%. The researchers concluded that CK alone is not a sufficiently robust assessment tool and emphasized the need for a multi-marker approach, complemented by load data. Even so, the increase in CK among injured players supported its relevance as a recovery indicator. Source: Tamujo et al., 2024 - The Physician and Sportsmedicine, 52(3), 271-276
- Ice hockey and rugby: contact sports have also adopted routine biochemical monitoring. Rugby teams, for example, run post-match panels with CK, LDH, and inflammation markers to assess the severity of microtrauma. Sports medicine publications describe how the early identification of abnormal CK and LDH values has led technical teams to reduce training loads and help prevent more serious injuries.
- Track and field and endurance sports: in individual sports, such as long-distance running, biomarkers are used to detect early signs of overload. National-team coaches collect capillary blood samples from elite runners before important training sessions. If elevated enzymes or electrolyte imbalances are detected, training intensity is reduced. This helps classify athletes according to their readiness and may help reduce the risk of functional overload before competition.
A particularly revealing example comes from the Red Bull Athlete Performance Center in Austria, where an integrated monitoring protocol was tested with a youth soccer team. Over four weeks, eight players provided daily blood microsamples to measure CK and circulating cell-free DNA - a marker of cellular breakdown. The protocol proved feasible and minimally invasive and was integrated smoothly into the training routine.
Players and coaches received the method positively. Based on the results, coaches adjusted individual loads: athletes with the highest post-match CK and DNA peaks received, for example, lighter recovery sessions.
Source: Haller et al., 2022 - Frontiers in Physiology
In Poland, researchers from the University of Szczecin and a medical institute developed a monitoring panel for swimmers that analyzed markers such as ALT, AST, LDH, ALP, creatinine, CRP, ferritin, and bilirubin immediately after training cycles. The results showed that variations in AST, LDH, and CK after training were especially significant, with more pronounced increases in sprinters than in long-distance swimmers. The authors recommended an expanded biochemical assessment rather than the exclusive use of CK, to better reflect overall metabolic stress.
Source: Kalinowski et al., 2022 - IJERPH, 19(14), 8580
Similar projects are now being developed in other countries: from U.S. college teams, where CK and hormonal testing are part of the preseason assessment, to national sports institutes in several countries, where biomarker research is reported to inform elite and Olympic preparation.
Rapid diagnostics: modern tools for elite sports
Until recently, performing these biochemical analyses required a full laboratory and a considerable amount of time. Today, portable diagnostic analyzers developed specifically for sports medicine enable a fast, mobile, and efficient process.
The Klinogicare® StarLab system, for example, can perform multi-parameter blood analysis in as little as 7-13 minutes, directly on the training field or in the clinic. A few drops of capillary blood are enough, and the device provides, within minutes, the results of a complete panel of key biomarkers, including:
- creatine kinase (CK);
- aspartate aminotransferase (AST);
- CK-MB;
- lactate dehydrogenase (LDH);
- alpha-hydroxybutyrate dehydrogenase (alpha-HBDH);
- glucose;
- amylase;
- creatinine;
- uric acid;
- electrolytes: potassium, sodium, chloride;
- total CO₂, that is, bicarbonate content.
Source: Klinogicare® StarLab POCT Analyzer
This level of accessibility makes it possible to integrate biochemical monitoring into an athlete's daily routine: after training, after a match, or as part of a routine check. Tests can be performed on site - in the locker room or treatment room - without the need to send samples to a central laboratory.
The use of objective numerical indicators instead of purely subjective assessments helps remove uncertainty. A coach no longer has to rely solely on how a player says they feel. A physician can refer directly to the result and say, for example:
"Your CK today is three times higher than your baseline value: this means your body is under stress and needs more recovery."
Or, conversely:
"All markers are within the reference range: you have recovered well and are ready for intense training."
This kind of evidence-based decision-making strengthens trust among athletes, coaches, and the medical team. Above all, it may help reduce the risk that unrecognized microtrauma develops into more serious muscle injuries or long-term problems.
Conclusion: why objective monitoring matters for a long athletic career
In high-performance sports, where training loads are increasing and competition is becoming ever more intense, integrating scientific methods and modern technologies is no longer an option but a necessity.
Regular monitoring of biochemical markers offers sports medicine physicians and performance-oriented teams a valuable preventive sports medicine tool: the ability to detect problems early, before symptoms appear, and to adjust the program accordingly.
Over the past three years, scientific evidence has clearly supported this approach. Blood biomarkers can provide valuable indicators of how an athlete's body responds to training and recovery, and they are increasingly present in elite practice.
Portable devices such as the Klinogicare® StarLab analyzer make this type of monitoring faster and easier to integrate into daily workflows and open new possibilities for making immediate decisions based on real data. Whether it is CK, electrolytes, or amylase, objective laboratory results reduce uncertainty and support smarter training planning.
Reducing training load in time or adding a recovery day when the data indicate it may help reduce the risk of muscle-fiber tears and other soft-tissue injuries. Each reduction in injury risk can translate into:
- the athlete's health preserved;
- resources saved for the club;
- greater competitive continuity without compromising long-term well-being.
In short: biochemical monitoring can be a strategic tool for extending athletic availability. Applied consistently, it allows clubs and sports organizations to raise their performance systems to a higher level, one in which results are achieved without unnecessary risks to those who make them possible.
Today, this is no longer merely a trend. It is becoming part of the standard of modern sport, supported by a growing body of peer-reviewed scientific literature:
https://www.mdpi.com/1424-8220/24/21/6862
References
Complete list of the literature and sources cited. All URLs were verified on 05/20/2026.
- The Role of Biomarkers in Monitoring Chronic Fatigue among Male Professional Team Athletes: A Systematic Review. Sensors, 24(21), 6862. https://www.mdpi.com/1424-8220/24/21/6862 Accessed on 05/20/2026.
- Injury incidence and injury patterns in professional football: the UEFA injury study. British Journal of Sports Medicine, 45(7), 553-558. https://pubmed.ncbi.nlm.nih.gov/19553225/ Accessed on 05/20/2026.
- Hormonal and Biochemical Parameters in Elite Athletes. Sports, 6(1), 19. https://www.mdpi.com/2075-4663/6/1/19 Accessed on 05/20/2026.
- Biochemical Markers of Recovery in Elite Swimmers. International Journal of Environmental Research and Public Health, 19(14), 8580. https://www.mdpi.com/1660-4601/19/14/8580 Accessed on 05/20/2026.
- Creatine kinase concentration on the second post-match day is not associated with risk of subsequent muscle injury in professional football players: a four-season cohort study. The Physician and Sportsmedicine, 52(3), 271-276. https://pubmed.ncbi.nlm.nih.gov/37548364/ Accessed on 05/20/2026.
- Comprehensive training load monitoring with biomarkers, performance testing, local positioning data, and questionnaires - first results from elite youth soccer. Frontiers in Physiology, 13, 1000898. https://www.frontiersin.org/articles/10.3389/fphys.2022.1000898/full Accessed on 05/20/2026.
- Serum Enzyme Activity and Muscle Damage in Football. Journal of Basic and Clinical Physiology and Pharmacology. https://pubmed.ncbi.nlm.nih.gov/28356830/ Accessed on 05/20/2026.
- StarLab POCT Analyzer - Technical overview. Klinogicare® technical resource. https://klinogicare.us/starlab-poct-analyzer-sports-ck/ Accessed on 05/20/2026.