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

Biochemistry of Sports
Biochemical Foundations of Athletes' Speed-Strength Qualities and Methods of Their Development
Biochemical Foundations of Athletes' Speed-Strength Training Methods

The structural factors underlying human speed-strength capacities (such as sarcomere length in myofibrils and The ratio of fast-twitch to slow-twitch Muscle fibers) are genetically determined. Therefore, the primary methodological approach to enhancing athletes' speed-strength qualities is the Selection of means and Methods designed to improve Myosin ATPase activity and promote the synthesis of contractile Proteins in Muscles. Currently, two main methodological techniques are used to achieve these goals in speed-strength sports: the maximum effort method and the repeated maximum-effort exercise method.

To train the capacity for maximum manifestation of speed-strength qualities, exercises are used that closely mimic the biodynamic Structure of competitive exercises, or the competitive exercises themselves. They are performed with ultimate mobilization for maximal exertion, featuring a low number of repetitions and unstructured rest intervals that are sufficient for recovery and re-mobilization for the next maximal effort (typically 1.5–2 minutes of rest between exercises).

The critical volume of exercises involving the maximum manifestation of strength, speed, or power is determined by the critical concentration of PCr in the muscles (approximately 1/3 of the total alactacid anaerobic capacity), below which maintaining the maximum rate of ATP resynthesis becomes impossible. Based on this PCr reserve, one can continuously perform up to 5–6 repetitions of such exercises. With freely regulated rest intervals within a single training session, an exercise can be repeated 10–12 times without a noticeable drop in peak power. A higher number of repetitions leads to localized fatigue, resulting in impaired movement coordination and reduced contraction power. A decrease in muscle PCr concentration below the critical threshold triggers enhanced Glycolysis, lactic acid accumulation, and a sharp drop in intracellular pH. These intracellular environmental changes inhibit myosin ATPase and, consequently, reduce the maximum exercise power. Therefore, training must be halted as soon as a pronounced drop in peak power or a sharp shift in Blood lactate levels and acid-base balance is observed (Fig. 178).

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Fig. 178. Dependence of blood lactate concentration and work output on the number of repetitions in short-term maximal-intensity exercises (arrows indicate the number of repetitions at which maximum power can be maintained without increasing glycolytic lactate production)

The repeated maximum-effort exercise method is used to stimulate contractile Protein Synthesis AND increase muscle mass. A wide range of exercises capable of sufficiently loading the target muscle group can be employed for this purpose. The resistance overcome typically does not exceed 70% of maximum isometric strength. Exercises are performed with a high number of repetitions until failure.

When resistance exceeds 50% of maximum isometric strength, Blood flow through the muscle drops sharply, leading to localized Hypoxia. Under these conditions (amid a deficit in aerobic energy production), alactacid anaerobic reserves are heavily depleted, large amounts of free creatine accumulate in the muscles, and glycolysis-driven lactic acid production increases significantly. Due to the shortage of high-energy phosphate compounds during high-volume work, Muscle Proteins break down, accumulating degradation products such as low-molecular-weight Peptides and Amino Acids. Protein breakdown products, along with free creatine, act as activators of protein synthesis during the recovery period following speed-strength workouts, once normal tissue oxygenation and nutrient delivery are restored. The accumulation of lactic acid during maximal exertion and the resulting shift in intramuscular osmotic pressure promote the retention of nutrient-rich intercellular fluid within the muscles. With systematic repetition of such training sessions, the concentration of contractile proteins and total muscle mass increase significantly.

A judicious combination and sequential application of both methods during training can ensure a high level of development of an athlete's speed-strength qualities.

Review Questions

1. What physiological factors determine speed-strength qualities at the level of individual motor units?

2. What biochemical factors influence the manifestation of speed-strength qualities?

3. What are the conditions required for achieving maximum muscular strength, velocity, and power During Muscle contraction?

4. What is the relationship between strength and the speed of muscle contraction?

5. What Biochemical changes in muscles are necessary for The Development of speed-strength qualities?

6. What exercises are used during training to develop speed-strength qualities?

7. Characterize the maximum effort method and the repeated maximum-effort exercise method.