Biochemical Foundations of Human Vital Activity - Volkov, N. I., & Nesen, E. N. 2000

Biochemistry of Sports
Biochemical Control in Sports
Biochemical Monitoring of Training Status, Fatigue, and Recovery in Athletes

The level of conditioning in the practice of biochemical monitoring of an athlete's functional state is assessed by changes in Blood lactate concentration during standard or maximal physical exertion for a given group of athletes. A higher level of conditioning is indicated by:

✵ lower lactate accumulation (compared to untrained individuals) during standard exertion, which is associated with an increased contribution of aerobic mechanisms to the Energy supply of this work;

✵ greater accumulation of lactic acid during maximal work, which is associated with an increased capacity of the glycolytic energy supply mechanism;

✵ an increase in the OBLA (onset of blood lactate accumulation — the work intensity at which blood lactate levels rise sharply) in trained individuals compared to untrained ones;

✵ longer sustainable work at the OBLA level;

✵ a smaller increase in blood lactate content with rising work intensity, which is explained by the optimization of anaerobic processes and the economical use of the body's energy resources;

✵ an increased rate of lactate clearance during the recovery period following physical exertion.

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Fig. 219 Changes in the rate of Oxidation of Fatty acids (1) and CARBOHYDRATES (2) during prolonged muscular work under METABOLISM/18.html">The Influence of aerobic-oriented training

As the level of conditioning increases in endurance sports, total blood volume increases: in men — from 5–6 to 7–8 L, in women — from 4–4.5 to 5.5–6 L, which leads to an increase in Hemoglobin concentration up to 160–180 g ⋅ L^-1 in men and up to 130–150 g ⋅ L^-1 in women.

Monitoring fatigue and recovery processes, which are essential components of athletic activity, is necessary to assess exercise tolerance and identify overtraining, ensure adequate rest time after physical exertion, evaluate the effectiveness of performance-enhancing Methods, and address other tasks.

Fatigue caused by maximal and submaximal physical exertion is interrelated with the depletion of energy substrate reserves (ATP, PCr, Glycogen) in the Tissues supporting this type of work and the accumulation of their metabolic byproducts in the blood (lactic acid, creatine, inorganic phosphates), and is therefore monitored using these indicators. During prolonged strenuous work, the onset of fatigue can be detected by a sustained elevation in blood urea levels after the cessation of work, changes in blood immune system components, and a decrease in hormone concentrations in blood and urine.

In sports Diagnostics, to detect fatigue, the concentrations of sympathoadrenal system Hormones (adrenaline and its metabolic products) in blood and urine are typically determined. These hormones reflect the degree of stress in the body's adaptive responses. When physical loads are inadequate to the functional state of the body, a decrease is observed not only in hormone levels but also in the precursors of their synthesis in the urine, which is associated with the depletion of the biosynthetic reserves of the Endocrine glands and indicates overstrain of the body's regulatory Functions controlling adaptive processes.

For the early Diagnosis of overtraining and the hidden phase of fatigue, monitoring the functional activity of The Immune System is employed. To this end, the count and functional activity of T- and B-lymphocyte Cells are determined: T-lymphocytes mediate cellular Immunity and regulate B-lymphocyte function, whereas B-lymphocytes are responsible for humoral immunity, with their functional activity assessed by the level of IMMUNOGLOBULINS in blood serum.

Analyzing immune system components requires specialized conditions and equipment. When implementing immunological monitoring of an athlete's functional state, it is essential to establish their baseline immunological status followed by continuous monitoring across various periods of the training cycle. Such monitoring helps prevent The breakdown of adaptive mechanisms, immune system exhaustion, and The Development of infectious diseases in elite athletes during training and preparation for major competitions (especially when undergoing rapid time-zone or climate changes).

Body recovery involves replenishing the energy substrates and other substances expended during work. Their restoration, as well as The rate of metabolic processes, do not occur simultaneously (see Chapter 18). Understanding the recovery timeframes for various energy substrates in the body plays a crucial role in the proper Structuring of the training process. Recovery is assessed by tracking changes in the levels of carbohydrate, lipid, and protein metabolites in the blood or urine that undergo significant alterations due to training loads. Among all Carbohydrate Metabolism indicators, the rate of lactic acid clearance during rest is most frequently studied, alongside Lipid Metabolism indicators such as the elevation of blood Fatty acid and ketone body levels, which serve as the primary substrate for aerobic oxidation during rest, as evidenced by a decrease in the respiratory exchange ratio. However, the most informative indicator of recovery after muscular work is the Protein metabolism byproduct — urea. Muscular activity enhances the Catabolism of tissue Proteins, leading to elevated blood urea levels; therefore, the normalization of its concentration in the blood indicates the restoration of Muscle Protein Synthesis AND, consequently, overall body recovery.