Can blood tests tell you whether training is too demanding?

The watch records the training, the athlete reports fatigue and the exam adds another number. The temptation is to choose one of these indicators as a definitive response on recovery. But they observe different parts of the same situation.

A high-level triathletes survey helps to understand why following trends is more useful than looking for an exam that works as a green or red light.

What was accompanied

Cejuela and collaborators gathered data from 20 triathletes men from the same group in the seasons from 2022 to 2025, with variable participation between the years. The follow-up covered preparatory periods and combined objective load, perceived effort, urea, creatine kinase (CK) and cycling evaluations.

The urea increased in the periods of moderate and high load. Higher subjective load was associated with higher elevation of this marker, while greater increases in urea were related to lower gains in certain cycling indicators. CK did not present consistent associations with the load. They are observational relationships: they do not demonstrate that reducing urea would lead to improved performance.

Load performed and response to load are different questions

“How much did I do?” and “how much did this require of me?” do not necessarily have the same answer. Power, time and distance describe aspects of the work. perceived exertion adds how that task was experienced that day.

This distinction is important when a usual session starts to seem disproportionately difficult. Ignore the feeling because the volume has not changed eliminates relevant information. On the other hand, an isolated bad feeling also does not explain all preparation.

The exam enters this conversation as another measure, which needs context and professional interpretation. Using it to pursue an ideal number without considering the person can exchange an understanding problem for a false precision.

Editorial example: the number only gains meaning within the sequence

An athlete finishes a difficult block and has a different result than usual. Before automatically assigning it to overtraining, it is necessary to review the collection conditions, recent routine and clinical history. The result gains another relevance if it coincides with persistent worsening of performance, unsatisfactory recovery and increasing effort for known tasks.

This reasoning does not establish a diagnosis. It organizes the information for an appropriate evaluation. The decision no longer depends on “the examination has gone up” and starts to ask if different signs tell a coherent story.

Similarly, an apparently normal result does not eliminate important complaints. The function of monitoring is to help interpret the athlete without replacing it.

What limits the application?

The group was small and trained within the same context. There was no systematic follow-up throughout the competitive phase, and the performance was evaluated in cycling. Therefore, there is no basis for turning these findings into a rule for women, amateurs or for the three segments of the competition.

There is also a difference between finding an association and demonstrating that a monitoring strategy improves results. This study did not compare two random programs, one guided by exams and the other without them.

The most useful editorial application is to combine consistent records: what was done, what was the perception, how the performance evolved and what health assessment adds. The study supports an integrated reading; it does not offer a diagnostic exam for overtraining.

Cada um no seu ritmo. Juntos no caminho.