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

Biochemistry of Sports
Regularities of Biochemical Adaptation in the Process of Athletic Training
Physical Exertion, Adaptation, and Training Effect

Sports training should be viewed as a process of targeted adaptation of the body to physical exertion. The physical loads utilized during training act as the primary stimulus (trigger), inducing adaptive changes within the body. In terms of content, METABOLISM/2.html">THE CONCEPT OF "physical load" is broader than that of "Physical Exercise." In sports training theory and practice, physical load refers to any form of muscular activity involving the single or repeated execution of a specific type of physical exercise that triggers pronounced functional (PHYSIOLOGICAL AND BIOCHEMICAL) Changes in the body, thereby contributing to enhanced training status. In the simplest case, a single load may consist of performing one exercise, but most often it is a combination of numerous exercises performed repeatedly within a single training session.

The direction and magnitude of biochemical changes occurring in response to applied physical loads determine the training effect. The degree to which physical load impacts the body depends on its selected characteristics—intensity and duration of the exercise, number of repetitions, duration and nature of rest intervals between them, and the type of exercises used. Altering any of these physical load parameters induces strictly defined BIOCHEMICAL SHIFTS IN the body; their combined impact leads to substantial metabolic restructuring, or adaptation, which is manifested by improved functional preparedness (fitness) and elevated athletic performance.

Biochemical adaptation of the body refers to the set of biochemical processes that ensure its efficient and economical operation under conditions of various environmental factors, while maintaining a relative level of Homeostasis. The governing factor in adaptation is the highly efficient functioning of metabolic regulatory systems and physiological systems.

The adaptation of the body to physical exertion, much like to any other stimulus, is phase-based in nature. Depending on The Nature and timeframe of adaptive changes within the body, two stages of adaptation are distinguished: acute and long-term (chronic) adaptation. The stage of acute adaptation is the immediate response of the body to a single bout of physical exertion. It is realized through pre-existing biochemical mechanisms and is primarily limited to changes in Energy Metabolism and its vegetative support Functions. The long-term adaptation stage spans a considerable period, developing gradually (based on the repeated realization of acute adaptation) As a result of the accumulation of residual effects from recurring loads; it is associated with The Emergence of Structural and functional changes in the body formed through the activation of the GENETIC APPARATUS OF functioning Cells under The Influence of load, along with enhanced Synthesis of specific Proteins within them. The interrelation scheme of individual links between acute and long-term adaptation is shown in Fig. 191.

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Fig. 191 Interrelation of the links of acute and long-term adaptation

The intensification of contractile activity in Muscles during physical exertion leads to noticeable shifts in energy supply systems; specifically, the balance of high-energy phosphates in The Cell changes, which is accompanied, as noted earlier, by an intensification of ATP synthesis processes and the restoration of the disrupted high-energy compound balance. These processes constitute the initial link of acute adaptation. At the same time, the disrupted balance of high-energy compounds at the moment of physical exertion activates another, more complex level of regulation. As seen in Fig. 191, the intermediate link, designated as the regulatory factor, controls The activity of the genetic apparatus and determines The rate of synthesis of Nucleic Acids and specific proteins within the cell. Free creatine, cAMP, as well as certain Peptides or Steroid Hormones can act as the regulatory factor in skeletal muscles. In this way, during long-term adaptation under the influence of physical exertion, the synthesis of Nucleic Acids and Proteins is activated, leading to the growth of contractile structures in the Muscle, enhanced functioning efficiency, and a more refined energy supply.

In accordance with the phase-based nature of adaptation processes to physical exertion, sports theory and practice generally distinguish Three types of training effects: acute, delayed (prolonged), and cumulative. The acute training effect is determined by the magnitude and nature of biochemical changes occurring in the body directly during physical exertion and during the immediate recovery period (the first 0.5–1 h post-exercise), when the oxygen debt accumulated during work is eliminated. The delayed training effect is observed in the late phases of recovery following physical exertion. Its essence consists of plastic processes stimulated by work, aimed at replenishing the body's energy resources and accelerated reproduction of cellular structures that were degraded during work and are newly synthesized. The cumulative training effect arises as a result of the successive accumulation of residual effects from many loads or A large number of acute and delayed effects. The cumulative training effect embodies biochemical changes associated with enhanced synthesis of nucleic acids and proteins, observed over an extended training period. The cumulative training effect is expressed in increased work capacity indicators and improved athletic results.