Blood-Based Biomarkers for Managing Workload in Athletes: Considerations and Recommendations for Evidence-Based Use of Established Biomarkers

Abstract

Blood-based biomarkers can provide an objective individualized measure of training load, recovery, and health status in order to reduce injury risk and maximize performance. Despite enormous potentials, especially owing to currently evolving technology, such as point-of-care testing, and advantages, in terms of objectivity and non-interference with the training process, there are several pitfalls in the use and interpretation of biomarkers. Confounding variables such as preanalytical conditions, inter-individual differences, or an individual chronic workload can lead to variance in resting levels. In addition, statistical considerations such as the detection of meaningful minimal changes are often neglected. The lack of generally applicable and individual reference levels further complicates the interpretation of level changes and thus load management via biomarkers. Here, the potentials and pitfalls of blood-based biomarkers are described, followed by an overview of established biomarkers currently used to support workload management. Creatine kinase is discussed in terms of its evidence for workload management to illustrate the limited applicability of established markers for workload management to date. We conclude with recommendations for best practices in the use and interpretation of biomarkers in a sport-specific context.

Relationship Between Objective and Subjective Markers of Muscle Recovery in Professional Handball Players

“…At the explicit express of the coaches of the team studied, we did not perform any further objective measures, although it would have been interesting to additionally examine muscle function, for example, during the countermovement jump or the squat jump, as Perkins et al 15 did in their study. In the present study, CK showed characteristics consistent with the literature on athletes: significantly higher values after several days of intense exercise than after an average of 40 hours of rest, 14,21 significant interindividual variability, 14,21,22 and the repeated-bout effect during the preseason. 14,21 Thus, our hypothesis about the behavior of CK in relation to the current recovery-stress state in these handball players was confirmed.…”

“…For this reason, CK is considered an important marker for the assessment of muscular stress and recovery and is widely used in sports medicine, research, and sports practice. [12][13][14] The short-term response of CK to training or match load and long-term changes over the course of a season have also been investigated in high-level handball players. 16,19,20 Therefore, we decided to use the biomarker CK as an objective measure to assess muscle stress and recovery in this observational study.…”

“…The muscle enzyme creatine kinase (CK) can be used as such an additional objective measure, which has been identified as an important biomarker for monitoring muscle recovery in team sports despite several disadvantages. [12][13][14] A recently published study 15 examined the relationship between SRSS and squat jump parameters, hydration status, and venous cortisol and CK levels in collegiate weightlifters. In this study, no significant relationships were observed between the SRSS items and CK levels, except for a significant positive correlation between the SRSS stress item Negative Emotional State and CK.…”

Reduction in systemic muscle stress markers after exercise-induced muscle damage following concurrent training and supplementation with specific collagen peptides – a randomized controlled trial

“…Severe myofibrillar damage, particularly as it occurs after unaccustomed eccentric exercise bouts, usually results in significant increases in CK, LDH and MYO, which have been extensively used as indirect biomarkers to monitor the extent of acute stress as well as recovery ( 35 ). The activity of both cytosolic enzymes (CK, LDH) during a nine ( 10 ) and 33-day ( 13 ) CP supplementation period was not lower compared to a placebo after muscle-damaging exercise, which could have indicated either reduced acute muscle stress or accelerated reconstruction of damaged tissue.…”

A Narrative Review on Adipose Tissue and Overtraining: Shedding Light on the Interplay among Adipokines, Exercise and Overtraining

“…-Biochemical markers, including creatine kinase (CK), urea, uric acid, ammonia, blood lactate, and plasma glutamine, have undergone extensive study across various athletes [57,58]. These markers are already used in many areas of sport to evaluate an athlete's training response, helping coaches to identify workload and prevent injuries [59]. CK activity reflects both the intensity and volume of exercise.…”