Introduction: Anabolic hormones and muscle
The hormones that influence muscular growth are known as anabolic hormones. With a little help from some thyroid hormones, these hormones (like testosterone, growth hormone, insulin, and insulin-like growth factor or IGF-1) help build all kinds of body tissue. They also block catabolic hormones. such as cortisol and progesterone, which destroy muscular tissue. As you already know, testosterone and growth hormone rise when men train with weights. Some studies have shown that weight training does not significantly increase testosterone in women, but it does increase the levels of growth hormone in the blood. Maybe this is one reason why women’s muscles don’t get as large as men’s; they don’t have that double shot of hormones. But even just a healthy level of growth hormone is useful to have around. Not only does it stimulate new tissue growth, but it also helps the body break down fat to use for energy and improves immune function.
Insulin-like growth factor 1 (IGF-1)
IGF-1 stands for insulin-like growth factor, formerly called somatomedin. It is a polypeptide hormone that is produced in the liver and muscle tissue. Its primary effect is to stimulate protein synthesis in bone, cartilage, and muscle. IGF is responsible for the muscle growth that occurs during puberty. It boosts amino acid and glucose transport into cells. It also makes muscles more sensitive to insulin’s effects and increases the number of muscle cells in your tissue, which can grow larger and stronger through weight lifting. IGF-1 is controlled by the intensity of muscle contraction, leading to an increase during exercise and a decrease afterward.
Why does this hormone have the word insulin in its name?
The name insulin-like growth factor reflects the fact that this substance has insulin-like actions in some tissues, though it is far less potent than insulin in decreasing blood glucose concentrations.
Functions of IGF-1 | What does IGF-1 do?
- Works with GH (growth hormone) to improve muscle protein synthesis and mechanical restructuring of muscle tissue;
- Stimulates production of satellite cells used to repair damaged protein structures;
- Possess some ability to decrease blood glucose levels;
What is the difference between the IGF-1 and IGF-2?
These two factors, despite the similarity of their names, are distinguishable in terms of specific actions on tissues because they bind to and activate different receptors. Long story short, the production of IGF-2 is less dependent on the secretion of growth hormone than is the production of IGF-1, and IGF-2 is much less important in stimulating linear growth.
What foods and nutrients increase insulin-like growth factor 1?
- Researchers have found that supplementing with zinc significantly increases circulating IGF-1 levels, and increases the synthesis and action of IGF-1 in the body.
- Besides supplementing, you should also eat plenty of healthy, whole foods that contain zinc.
- Eating enough high-quality protein is critical if you want to increase your IGF-1 levels. Research shows that low protein intake is associated with a major reduction in IGF-1. Animal protein and red meat in particular has been shown to increase IGF-1 concentrations.
- Taking extra Vitamin C, Vitamin D, and Vitamin B1 is another way to increase IGF-1.
- Research shows that magnesium and selenium levels are strongly and independently associated with total IGF-1 levels.
- Certain supplements and herbs also increase insulin-like growth factor 1 (IGF-1): probiotics, dehydroepiandrosterone (DHEA), taurine, resveratrol, leucine, colostrum, Acetyl-L-carnitine, creatine, Hydroxy Methyl Butyrate (HMB), and Coenzyme Q10 (CoQ10).
What lifestyle changes increase IGF-1 production?
- Reducing abdominal fat (if overweight or obese)
- Avoiding fasting
- Avoiding alcohol consumption
- Engaging in regular exercise (intense/strenuous exercise and HIIT workouts)
- Getting quality sleep
- Sauna sessions. Certain studies suggest that 60-minute sauna sessions twice daily for one week can significantly increase the production of growth hormone, which is believed to also apply to IGF-1.
Effects of resistance training on insulin-like growth factor 1
We already know that exercise stimulates GH (growth hormone) secretion, increasing circulating GH within 15–20 min after the onset of exercise. The maximum peak of GH is detected shortly after the exercise. In general, the more intense and longer the exercise, the greater the GH release. But what about IGF-1?
The review shows evidence from several studies that high resistance training has a favorable impact on musculoskeletal health that can be evaluated by IGF1. IGF1 has an important role in maintaining the quality of skeletal muscle mass. IGF1 stimulates myogenin expression by satellite myoblasts. The decrease in the level of the anabolic hormone IGF-1 in old age greatly influences Growth Hormone (GH), which plays a role in increasing the number of myocytes.
Resistance training improves the effectiveness of both agonist and antagonistic muscle units, which is necessary for muscular growth. As compared to high-intensity activities, high-resistance training resulted in a substantially higher increase in GH and cortisol concentrations. IGF-1, testosterone, and insulin were all increased by exercise. The increase in hormones associated with anabolic signals supports homeostatic mechanisms for target metabolism and repair involving skeletal muscle.
Further studies still need to be carried out in various populations to investigate the effect of resistance training on increasing the IGF1 hormone for the prevention and treatment of sarcopenia.
The things that inhibit IGF-1
- Aging, since older age is associated with decreased production of growth hormones;
- Calorie restriction, fasting, extreme diets, and protein restriction;
- High insulin levels, since this may decrease the body’s need for IGF-1;
- Sedentary lifestyle/lack of exercise;
- Sleep deprivation;
- Higher estrogen levels, such as from high intake of plant lignans and phytoestrogen foods like soy and flax;
- High alcohol intake;
- High-stress levels;
Summary
Insulin-like growth factor (IGF-1), also commonly referred to as mechano growth factor, has a molecular structure similar to insulin. IGF-1 is an important hormone stimulated by the same mechanisms that produce HGH (human growth hormone). IGF-1 is a peptide hormone produced in the liver. It supports the function of HGH to repair protein damaged during exercise, making it an important hormone for promoting muscle growth.
