Cortisol or hydrocortisone is produced by the adrenal glands (situated above the kidneys). It belongs to a group of steroid hormones (made from cholesterol) called glucocorticoids and plays an important regulatory role in ‘housekeeping’ functions (e.g. maintain optimal blood glucose levels during fasting) and the immune system (e.g. allergies, asthma, autoimmune diseases). Cortisol levels peak in the morning, fluctuate throughout the day with stress and reach their lowest at night. Excess cortisol in the blood (hypercortisolaemia) is seen to cause a progressive decline in the muscle’s protein building ability, thus leading to loss in muscle mass and weakness. Variations in hormone levels have been known to predict the catabolic (breakdown) and anabolic (growth) state of our body adapting to stress and recovery from training sessions. Generally, the testosterone to cortisol ratio (T:C) is used. Higher testosterone indicates an anabolic state whilst higher cortisol indicates overall catabolism.
Cortisol & Bodybuilding
Exercise especially resistance training is important in promoting anabolism which increases muscle protein synthesis (MPS). Although there is an overall increase in protein synthesis, our muscles still remain in a catabolic state without adequate nutritional support. Thus, nutritional supplementation is critical to all phases of training as it can encourage an anabolic environment in response to endurance or resistance exercises. A combination of carbohydrate and protein alone has been demonstrated to reduce cortisol levels whilst increasing insulin levels and growth hormone levels after exercise. Furthermore, it is found that there is a reduction in muscle damage and increased production of muscle proteins. Essential amino acids (EAAs) supplementation has been shown to stimulate MPS thus inhibiting undesirable losses in muscle mass, as has the mother of all bodybuilding amino's L-Glutamine. Coupled with another study demonstrating the beneficial effects of branched chained amino acids (BCAAs) on muscle, these supplements which reduce muscle damage would ultimately promote endurance to high-intensity training and subsequent rise in testosterone levels.
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