HUMAN BIOCHEMISTRY - L. V. Kapilevich - 2016

PART 1. SPORTS BIOCHEMISTRY

BIOCHEMICAL BASES OF ATHLETIC PERFORMANCE

Performance is manifested in maintaining a given level of activity for a certain period of time and is determined by two groups of factors: external and internal.

External factors include the informational Structure of signals (i.e., the amount and presentation format of information), CHARACTERISTICS OF THE working environment (workplace ergonomics, Temperature, lighting, presence of hazardous factors, etc.), and interpersonal relationships within the team.

Internal factors include the level of training, conditioning, endurance, and emotional stability.

Components of Athletic Performance

Athletic performance (special working capacity) refers to the state of an athlete's body that enables them to perform specific physical loads of a defined intensity and duration.

The manifestation of athletic performance depends on many factors, but this section will focus on Bioenergetics, as it is impossible to perform any work without Energy Expenditure.

As is known, the energy supply for muscular work is carried out mainly through three pathways of ATP resynthesis: the creatine phosphate (alactic), glycolytic (lactic), and aerobic (tissue Respiration) pathways. Depending on the dominance of a particular ATP resynthesis pathway in meeting the energy demands of the work performed, three performance components are distinguished: alactic, lactic, and aerobic performance.

Alactic Performance

Maximum alactic power depends, on the one hand, on the concentration and activity of the enzyme creatine kinase (which transfers a phosphate group from creatine phosphate to ADP) and creatine phosphate itself; on the other hand, the power of this reaction depends on the Muscles' energy demand and is therefore determined by the maximum rate of ATP consumption generated by the muscles. The maximum duration for maintaining alactic power is 6-12 seconds. Alactic capacity depends on the reserves of Creatine phosphate in the Muscle.

It is possible to increase creatine phosphate reserves by using physical exercises that lead to its rapid depletion in the muscles.

An interval training method is applied. The athlete is asked to perform a series of 4-5 maximum-power exercises lasting 8-10 seconds. Rest between exercises in each series is 20-30 seconds. The rest duration between series is 5-6 minutes.

During each exercise, creatine phosphate reserves in the muscles decrease. During the rest periods between exercises, The Glycolytic Pathway of ATP resynthesis is activated. However, supercompensation does not develop, as the rest is followed by a new series of exercises. As a result, creatine phosphate reserves in the muscles gradually become depleted. As soon as a critical threshold of decrease in creatine phosphate concentration is reached in the working muscles, the power of the performed loads immediately drops. Typically, this state is reached after 8-10 series of exercises.

During the post-workout recovery period, pronounced creatine phosphate supercompensation is observed. Repeated application of such training sessions should lead to an increase in muscle creatine phosphate reserves and positively affect The Development of the athlete's speed-strength qualities.

In addition, alactic performance is characteristic of maximum-power exercises (strength exercises), and the strength developed is directly related to the volume of muscle fibers.

To develop muscle hypertrophy, physical loads are applied that lead to myofibrillar damage and subsequent supercompensation. Various resistance exercises are used for this purpose.

The most effective resistance is 85% of maximum strength. Each exercise (targeting specific muscles) is performed in series, ranging from 5 to 10, with a rest interval of a few minutes between them. The speed of exercise execution is determined by the training goal. For the preferential increase in muscle mass, exercises are performed at a slow or moderate pace. For the simultaneous development of strength and speed, exercises are performed in an explosive-smooth regime: the initial phase of the movement is performed at high speed, and it concludes as smoothly as possible.

Recovery time after speed-strength training is 2-3 days. By alternating the muscle groups targeted by the loads, training sessions can be scheduled with shorter rest intervals.

To replenish Proteins broken down during work, an increased intake of Amino Acids is required during recovery. This necessitates a diet with an elevated protein content, amounting to 150-200 g per day.

Lactic Performance

Maximum lactic power is determined primarily by the concentration and activity of key glycolytic Enzymes. The duration for maintaining the maximum power of this metabolic process is 30-60 seconds and is determined, on the one hand, by the resistance of glycolytic enzymes to a drop in medium pH (increased medium acidity inhibits The activity of glycolytic enzymes, thereby suppressing energy production) and the Stability of the acid-base balance of the internal muscle environment under conditions of enhanced lactate production. On the other hand, the maintenance time of maximum glycolytic power is limited by muscle fatigue factors that reduce contraction intensity.

It follows from the above that to trigger adaptation processes aimed at increasing maximum glycolytic power, the duration of the load should correspond to the maintenance time of the maximum power of this metabolic process, which is 30-60 seconds. Rest between sets must be sufficiently long to ensure the removal of metabolic products from the muscle and the development of high glycolytic power in the subsequent set. The resistance of the muscle fiber pH to lactic acid efflux and the resistance of Key Enzymes to pH reduction are developed through training accompanied by maximum lactate accumulation in the muscles. These can be high-intensity loads lasting 1.0-1.5 minutes until muscular failure caused by severe acidification, or shorter loads lasting 20-40 seconds with equally short rest intervals, leading to the cumulative accumulation of lactate in the muscles.

Aerobic Performance

Maximum aerobic capacity depends primarily on mitochondrial density within muscle fibers, the concentration and activity of oxidative enzymes, and The rate of oxygen delivery deep into the fiber. The volume of oxygen available for oxidative reactions is limited both by systemic factors of overall physical performance and by A number of local intramuscular factors. These include muscle capillarization, Myoglobin concentration, and muscle fiber diameter (the smaller the fiber diameter, the better its oxygen supply and the higher its relative aerobic capacity). The rate of ATP production via oxidation peaks during the 2nd to 3rd minute of exercise, which is associated with the time required to initiate the multiple processes responsible for delivering oxygen to the Cell/35.html">Mitochondria.

Training aimed at developing aerobic endurance should enhance the functional capacity of the cardiorespiratory system, increase THE RED Blood cell count and Hemoglobin content in the blood, raise myoglobin concentration in muscle Cells, and ensure a better supply of energy substrates to working Organs.

To this end, various protocols of repetition and interval training are employed, as well as continuous prolonged exercise at a steady or variable intensity.

For example, circulatory interval training is utilized, involving series of relatively short, high-intensity bouts lasting from 30 to 90 s, alternated with equally short rest intervals. The effectiveness of this method lies in the fact that oxygen consumption remains elevated during the initial minutes of rest following exercise cessation due to the repayment of the oxygen debt (obtaining via oxidative pathways the energy required to replenish ATP and creatine phosphate stores and to clear lactic acid from the muscles). Consequently, during the brief rest period, oxygen consumption drops only slightly, while the muscles recover their strength by restoring ATP and creatine phosphate reserves and clearing Metabolic waste products, thereby enabling them to generate high force and drive high oxygen demand once again. As a result, throughout the entire 'circulatory' workout, oxygen consumption fluctuates only slightly around maximum values.

To increase myoglobin content in muscles, myoglobin interval training can be implemented. Athletes perform very short (no more than 5–10 s) moderate-intensity efforts alternated with equally short rest periods. These brief bouts of exercise are fueled primarily by oxygen stored in the muscle cells as a complex with myoglobin. The short rest intervals between exercises are sufficient to replenish these oxygen stores.

To increase the oxygen-carrying capacity of the blood and elevate myoglobin concentration, training in mid-altitude (hypoxic) conditions yields excellent results.

Specificity of Sports Performance

Each sport is characterized by its own specific type of physical performance. Performance is more specialized in sports that heavily tax anaerobic capacity, because performing sport-specific movements primarily engages only certain muscle groups. Consequently, training specifically targets and improves the performance of these exact muscle groups.

Aerobic performance is less specific. An athlete with a high level of aerobic capacity can manifest it not only in their primary discipline but also across Other types of muscular work. For instance, a well-trained cross-country skier may also achieve strong results in long-distance running, and so on.

Age-Related Aspects of Performance

As growth and body mass increase, physical performance improves, though individual performance components develop at different rates.

Alactic performance in children is low because their muscle creatine phosphate content is significantly lower than that of adults. The alactic pathway begins to develop around 15–17 years of age, peaks at 19–20 years, remains stable up to the age of 30, and declines thereafter.

Lactic performance in children and adolescents is also lower due to smaller muscle Glycogen stores and a high physiological sensitivity to increased acidity resulting from lactate accumulation. This pathway develops starting at 15–16 years of age, peaks at 20–22 years, and then declines rapidly.

Aerobic performance in children is similarly low, as the GROWTH AND DEVELOPMENT of the child's body demand significant energy expenditure. An intensive Development of the aerobic pathway is observed from 9–10 years of age, peaking only at 20–25 years, a level that can be maintained up to 40–45 years.

Self-Assessment Questions

1. Define the term 'sports performance'.

2. What factors determine the manifestation of sports performance?

3. During what types of Physical Exercise is alactic performance manifested?

4. What is the difference between tonic and phasic muscle fibers?

5. What is the difference between lactic and alactic performance?

6. List the factors that influence aerobic performance.

7. What constitutes the specificity of sports performance?

8. At what age do aerobic, lactic, and alactic performance begin to develop?

9. What training method can be used to improve alactic performance?

10. What types of training can be utilized to increase the oxygen-carrying capacity of the blood?