The subject of today’s blog is five of the key hormones: insulin, glucagon, testosterone, oestrogen and human growth hormone (HGH).
What are hormones?
Hormones are chemicals that help to regulate different bodily functions. Secreted by glands in our bodies, they are transported to various organs via the bloodstream.
Hormones are used by the endocrine system for homeostasis: the control of metabolism, from energy levels to reproduction, growth and healing (see our blog on: The Endocrine System).
What is the relevance of hormones to exercise?
Personal trainers will find it useful to understand the function of hormones as they can affect a client’s adaptations in a positive or negative way.
An overview of five key hormones:
Insulin and glucagon
These work in partnership to regulate blood sugar levels and provide the body with a steady supply of energy (see our blog on: What is the Glycemic Index and Glycemic Load?).
Whenever carbohydrates are consumed, the digestive system breaks them down into glucose, which provides fuel for our bodies as it travels through the bloodstream. The amount of glucose in the body depends on the food we choose to eat.
When blood sugar levels rise, the pancreas increases production of insulin, which directs cells to draw in glucose from the bloodstream, some of which is stored as glycogen When blood sugar levels fall, the pancreas secretes glucagon, which tells the liver and muscle cells to convert stored glycogen back into glucose, which is returned to the bloodstream in a process known as glycogenolysis.
If blood sugar levels are allowed to spike, as happens when people consume large amounts of sugar and carbohydrate in their diet, this can cause imbalances that ultimately lead to the development of Type 2 Diabetes (see our blog on: Personal Training: Diabetes).
Testosterone is secreted by the testes in men and, at a much lower level, by women’s ovaries. It affects muscle mass and strength as well as sex drive.
Oestrogen helps to regulate the reproductive cycle and sex drive in women, although it’s also present in low levels in men. It can also affect how fat is stored in the body.
Human Growth Hormone
Growth hormone is secreted by the pituitary gland and works alongside testosterone, promoting cell growth and regeneration, and affecting muscle mass and body fat levels. It is also important for human tissue in general, including promoting healthy brain function. Growth hormone levels are at their highest during puberty.
Factors that can affect the key hormones
Regular exercise – in particular high intensity training (see our blog on: The Crossfit Craze) – along with good nutrition and sufficient sleep can all help to regulate levels of hormones in the body and fight against the effects of ageing.
In future blogs, we will look at each of these hormones in more detail.