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

Biochemical Foundations of Human Vital Activity
Hormones as Metabolic Regulators
The Role of Hormones in Muscular Activity

Physical exertion leads to alterations in the Functions of many Endocrine glands, particularly those involved in mediating the body's general adaptation to stress.

The magnitude and direction of these changes in specific endocrine glands depend on the intensity and duration of physical activity, as well as the individual's level of physical conditioning. Short-term, acute bouts of exercise enhance the secretory activity of many glands, releasing higher amounts of Hormones into the bloodstream, which stimulates energy production and enhances physical performance. During prolonged physical work, however, hormone secretion declines. This can lead to the exhaustion of endocrine gland function, resulting in decreased physical performance and the onset of fatigue.

Systematic muscular activity enhances the functional reserve of the endocrine glands and increases hormone storage, although resting Blood levels of certain hormones (such as thyroxine and Insulin) may be reduced. Nevertheless, under METABOLISM/18.html">The Influence of physical exertion, the trained body responds with an upregulated secretion of hormones and the processes they regulate. Furthermore, the Mechanisms of Hormone action are optimized: there is an increase in the concentration of the second messenger cAMP in Muscles, along with heightened sensitivity of Enzymes to the messenger and of receptors to hormones, all of which contribute to superior physical performance.

The directional Changes in the blood concentrations of specific hormones during muscular activity, as well as their role in adaptive responses, are presented in Table 13 (↑ denotes an increase, ↓ denotes a decrease following intense physical exertion). As shown, certain hormones enhance the mobilization and utilization of CARBOHYDRATES and fats, thereby maintaining normal ATP levels in Cells and improving the body's adaptation to physical work. Other Hormones help maintain fluid balance by preventing dehydration, while still others stimulate the adaptive Biosynthesis of structural Proteins and Enzymes, supporting recovery and overall adaptation to physical training.

Class="center">TABLE 13. Directional Changes in Blood Hormone Concentrations During Muscular Activity

High physical performance and athletic achievement are determined by the coordinated interplay of all endocrine glands—often referred to as the hormonal ensemble. Dysfunction in any single gland disrupts metabolic efficiency, preventing an athlete from reaching peak performance. Only a properly structured training regimen can improve the functional capacity of the Endocrine System and prevent it from entering stages of exhaustion during heavy physical loads.

Review Questions

1. What are hormones and endocrine glands?

2. What are the general Properties of Hormones?

3. What is the Chemical Nature of hormones?

4. What is the MECHANISM OF ACTION of Steroid Hormones?

5. Explain The Mechanism of Action of Hormones that do not cross The Cell membrane.

6. Name the Pituitary Hormones and explain their physiological roles.

7. What is the Biological Role of THYROID HORMONES?

8. How do Pancreatic Hormones regulate blood glucose levels?

9. How do glucocorticoids and mineralocorticoids affect metabolism? Which glands secrete them?

10. Name the hormones of The adrenal medulla. What is their biological effect on metabolism?

11. What are the androgenic and anabolic effects of steroid hormones?

12. Which hormones regulate bioenergetic processes in the body, and how does this affect physical performance?

13. How does hormone metabolism change during muscular activity?

14. Which hormones influence the body's adaptation to physical exertion?