Blood tests, once limited to clinical diagnostics, are now making waves in the world of elite athletics as tools for physiological profiling and monitoring. These tests offer valuable insights into nutrient deficiencies, oxidative stress, inflammation, and red blood cell status, helping athletes optimize their performance by adjusting their diet, training load, and recovery strategies. Despite wide inter-individual variability in biomarkers, sports science and medicine practitioners can use statistical methods to analyze longitudinal data and identify meaningful changes in athletes.
Key Takeaways:
- Blood biomarkers have a growing role in profiling and monitoring athletes, with selection depending on the sport’s demands.
- Longitudinal data analysis helps establish individualized thresholds for tracking meaningful changes.
- Blood profiling offers an objective assessment of nutritional status and training load tolerance.
- Adhering to pre-analytic protocols is crucial to avoid poor quality data, such as considering posture, time of day, and recent food or exercise.
Blood Biomarker Profiling and Monitoring: Overlooked Considerations and Practical Applications in Sports Performance
Professional and Olympic-level athletes often receive comprehensive sports medicine and science support services aimed at optimizing performance and protecting their long-term health. Blood profiling and monitoring have become increasingly valuable tools for assessing training efficacy, informing nutritional strategies, and evaluating an athlete’s capacity to tolerate training loads. However, there is a lack of recent reviews on the practical application of blood biomarker profiling and monitoring in sports.
Blood tests can reveal various indicators of an athlete’s performance readiness, recovery status, and training adaptability. For instance, a high testosterone-to-cortisol ratio suggests better anabolic capacity and positive training outcomes, while low iron levels can compromise altitude training’s erythropoietic effects. Vitamin D deficiency can also negatively impact immunity, muscle repair, and bone health.
This article aims to provide a practical guide to blood biomarker profiling and monitoring, focusing on often overlooked considerations in sports applications. These include determining what is ‘normal’ for each athlete, pre-testing considerations like time of day, posture, and hydration status, sports-specific expertise for interpreting results, and understanding the effects of plasma volume shifts on biomarker measurements.
Blood biomarker profiling is essential for enhancing sports performance, with two approaches: screening and monitoring. Collaborative teamwork between sports medicine doctors, sports scientists, and biostatisticians is crucial for effective blood testing. Caution is advised when selecting technology for biomarker measurement. Pre-analytic and statistical factors are crucial for accurate data. Balancing benefits and risks of blood volume removal is vital to avoid negatively impacting athlete performance and health. Despite challenges, incorporating blood tests before and after physical testing can provide valuable insights.
Using Blood Profiling to Inform Nutritional Recommendations
Dietary habits of athletes are assessed to construct individualized dietary plans. Blood profiling provides an efficient, reliable, and quantitative means of assessing nutritional status. Nutritional blood biomarker profiling can be used to assess compliance and response to dietary interventions, and to determine whether timely nutritional adjustments are needed to optimize recovery and adaptation. Some nutrient blood tests, such as measurement of fatty acids incorporated in red blood cells (RBC) membranes, glycated hemoglobin (HbA1c), and red cell magnesium (Mg), reflect dietary exposure over the life of the RBC and provide useful indices of global dietary habits. Novel nutritional biomarkers include RBC fatty acids, biomarkers of fruit and vegetable intake, and biomarkers of amino acids.
Red Blood Cell Fatty Acids
Consumption of dietary fats can be assessed through the analysis of RBC fatty acids. RBC fatty acids are responsive to changes in the intake of fish, olive oil, and fish oil supplements. The omega-3 index (OM3I) represents the percentage of EPA and DHA as a proportion of total RBC fatty acids. Currently, the recommended target range for OM3I in athletes is 8–11%. Studies suggest that measuring and manipulating OM3I in athletes may augment both health and performance, although further research is needed.
Biomarkers of Fruit and Vegetable Intake
Fruits and vegetables (FV) are essential to athlete health, recovery, and performance. The measurement of serum carotenoids constitutes a valid means for assessing FV intake. Studies show that modifying FV intake can support athlete recovery and health, although more research is needed. It should be noted that this is not synonymous with high-dose antioxidant supplementation, where there is a risk of blunting adaptation.
Biomarkers of Amino Acids
Exercise training alters plasma blood amino acid concentrations. Glutamine (GLN) and glutamate (GLU) have been researched as a method of monitoring fatigued states in athletes, with noteworthy observations. The ratio of GLU to GLN consistently showed promise for monitoring training stress. Unfortunately, amino acid assays are not readily available in clinical or commercial laboratories, which may explain the lack of recent research. Metabolomic studies may reinvigorate this field, although metabolomic data are currently sparse in sport.
Monitoring Bioenergetic Hormones for Optimal Athletic Performance and Health
Assessing energy availability is vital for preventing negative health effects in athletes such as the female athlete triad or relative energy deficiency in sport (RED-S). Monitoring bioenergetic hormones can help protect athletes from unexplained underperformance syndrome, which can be caused by chronic low energy availability. Blood profiling is recommended for indirectly screening for energy availability. Hormonal biomarkers offer insight into energy availability and can provide meaningful data for physicians, sports practitioners, and coaches to adjust training and nutritional programs for optimal recovery and adaptation. Poor energy availability and hormonal suppression can also occur in male athletes, with significant effects on hormonal systems and performance. Nutritional interventions can restore hormone levels, demonstrating the sensitivity of these hormones to nutritional status.
How Blood Biomarkers Help Athletes Maximize Their Oxygen-Carrying Capacity
Elite athletes need to have high levels of oxygen-carrying capacity to boost their endurance performance, and this is where blood biomarkers come into play. Haemoglobin concentration in a blood sample is poorly correlated with total hemoglobin mass (tHbmass), so experts use carbon monoxide rebreathing and a recent attempt to estimate plasma volume based on biochemical markers to accurately measure tHbmass. Blood testing can also identify iron deficiency, a common issue in athletes who may have footstrike haemolysis, excessive sweating, or poor dietary habits.
Blood Biomarkers for Assessing Training Capacity and Managing Athlete Workload
Elite athletes need to balance training intensity with recovery to avoid maladaptation or injury. Blood biomarkers can be used to assess an athlete’s capacity to train and recover, such as measuring creatine kinase for muscle damage, pro-oxidant and antioxidant activity for oxidative stress, pro-inflammatory cytokines for inflammation, and cortisol, testosterone, and urea for anabolic or catabolic status. Biomarkers are especially useful in team sports, where players are subjected to various forms of stress, and they help coaches and sports scientists make informed decisions on training loads and recovery strategies.
Blood Biomarker Science: The Future of Elite Sport Performance?
The use of blood biomarkers in elite and professional sports is becoming increasingly popular, providing objective data for interdisciplinary sports science and medicine teams. While some nutritional biomarkers are well-established, others need further research to demonstrate their utility in sports. The success of blood-biomarker profiling or monitoring programs is dependent on the selection of appropriate biomarkers, timing of testing, interdisciplinary collaboration, and statistical methods. The future of blood biomarker science in sport looks promising, with the potential for new ‘-omics’ science and technology that analyzes an athlete’s blood without traditional venepuncture becoming commonplace.
