Growth Hormone

Original Editor - Lucinda hampton

Top Contributors - Lucinda hampton and Vidya Acharya  

Introduction

HGH function

Hypothalamus-Pituitary Complex

Human growth hormone (HGH), also known as somatotropin, is a 191 amino acid single-chain polypeptide. It is produced by somatotropic cells within the anterior pituitary gland.

HGH is secreted in a pulsatory way, generally following a circadian rhythm. Various physiological stimuli can cause HGH secretion, with the most influential non-pharmacological stimuli being sleep and exercise.

HGH has numerous roles throughout life, from growth itself (including the turnover of muscle, bone and collagen) to the regulation of particular aspects of metabolic function, for example increased fat metabolism and the maintenance of a healthier body composition in later life.

Once secreted, HGH remains active in the bloodstream for a few minutes, allowing enough time for the liver to convert it into growth factors, the most crucial being insulin-like growth factor (IGF-1), which has growth-promoting effects on every cell in the body. Together, IGF-1 and GH promote normal growth of bones and tissues.

The use or distribution of HGH without a medical need and prescription is considered illegal.

HGH Roles in Childhood and Adulthood

HGH acts on many parts of the body to promote growth in children. When the growth plates in the bones (epiphyses) have fused, HGH no longer increases height, but it still has important roles. In adulthood HGH impacts the bodies metabolism (how your body turns the food you eat into energy).

1. Growth: HGH induces growth in nearly every tissue and organ in the body. However, it is best known for its growth-promoting effect on cartilage and bone, especially in the adolescent years.
2. Metabolic Effects: HGH impacts metabolism primarily by up-regulating the production of insulin-like growth factor-1 and its subsequent effect on peripheral cells. Predominantly, cells move into an anabolic protein state with increased amino acid uptake, protein synthesis, and decreased catabolism of proteins. Most particularly it is known for its effect on bone growth and musculoskeletal anabolism
3. Regulation of lipid metabolism, body fat distribution, inflammation and vascular health . HGH secretion is effected by visceral fat. The adverse metabolic effects of increased visceral fat include HGH deficiency, with therapy to increase HGH significantly reduces visceral fat. Visceral fat accumulation is strongly associated with increased metabolic and cardiovascular risk, whereas subcutaneous fat appears to be beneficial with respect to metabolic health   A 2015 review reinforces this, indicating that growth hormone-releasing hormone (GHRH) may be beneficial for people with obesity.
4. Another role of HGH is blood sugar level control. HGH indirectly acts on blood glucose levels through the regulation of IGF-1, which mimics insulin's effect in the body, helping control blood sugar levels.

Physiotherapy Implications

Strength training

Exercise is a forceful physiological stimulus for growth hormone (GH) secretion, with both aerobic and resistance exercise bringing about a significant, acute increases in GH secretion. In opposition to previous suggestions that exercise-induced GH release requires that a "threshold" intensity be attained, recent research shows that regardless of age or gender, there is a linear relationship between the magnitude of the acute increase in GH release and exercise intensity.

GH secretion decreases with ageing and obesity, bringing about many. Exercise is a robust stimulus of GH secretion, as as such is a great natural way to promote eg better bone, joint and muscle health. See The influence of human growth hormone (HGH) on physiologic processes and exercise

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