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What is cortisol?

Cortisol is a hormone that belongs to a family of steroid hormones known as glucocorticoids. It’s secreted by the adrenal cortex, which is located in your adrenal glands that sit atop your kidneys. Cortisol is the main glucocorticoid in humans.

Glucocorticoids affect every cell in the body so needless to say, they’re pretty important.

In particular, glucocorticoids released in the body send feedback to the brain and influence the release of CRH (corticotropin-releasing hormone) and ACTH (adrenocorticotropic hormone). ACTH stimulates the adrenal glands to secrete cortisol. The rise in cortisol secretion follows ACTH release after a 15-minute to 30-minute delay.

Why is cortisol so important?

Cortisol accelerates the breakdown of proteins into amino acids (except in liver cells). These amino acids move out of the tissues into the blood and to liver cells, where they are changed to glucose in a process called gluconeogenesis. A prolonged high blood concentration of cortisol in the blood results in a net loss of tissue proteins and higher levels of blood glucose.

Isn’t this bad?

Well, not exactly. By raising plasma glucose levels, cortisol provides the body with the energy it requires to combat stress from trauma, illness, fright, infection, bleeding, etc.

Obviously, this is bad from a muscle breakdown perspective; however, the body is simply trying to preserve carbohydrate stores and deliver energy when it’s needed most. Acutely, cortisol also mobilizes fatty acids from fat cells and even helps to maintain blood pressure.

As it’s part of the inflammatory response, cortisol is necessary for recovery from injury. However, chronically high levels of cortisol in the blood can decrease white blood cells and antibody formation, which can lower immunity. This is the most important therapeutic property of glucocorticoids, since they can reduce the inflammatory response and this, in itself, suppresses immunity.

Thus, cortisol is:

• Protein-mobilizing
• Gluconeogenic
• Hyperglycemic

Whether these effects are “good” or “bad” depends on whether cortisol’s release is acute (ie brief and infrequent) or chronic (ie ongoing).

What you should know

Here are the cortisol reference ranges. Notice that they depend on the mode of measurement (urine vs serum) and time of day.

• Cortisol, free (urine) 20-90 mcg/day
• Cortisol (serum) 4-22 mcg/dL (morning specimen)
• Cortisol (serum) 3-17 mcg/dL (afternoon specimen)

Cortisol has a close relationship to exercise and training status.

For example, cortisol levels can be a sign of overtraining. To be indicative of overtraining, cortisol increases may need to be higher than 800 nmol/L.

Exercise type

The type of exercise regimen performed can dictate hormonal response.

The relationship between cortisol, other hormones, nutrition, and stress

Acute high intensity resistance exercise is associated with increased plasma cortisol concentration. In other words, after something like a sprint or a high-intensity conditioning or bodybuilding-style workout, plasma cortisol concentration increases. The response is similar to that seen of growth hormone. The most dramatic increases occur when rest periods are short and total volume is high.

Cortisol responses to increased training volume are variable. Response depends on specific training protocols and diurnal variations (variations over the course of the day).

Again, it is important to distinguish between acute and chronic cortisol release. When muscle glycogen concentrations are low, cortisol is released and fuel use shifts toward protein or fat so that judicious use is made of the little glucose that remains. However, in the long-term, excessive cortisol will encourage fat synthesis and storage, along with provoking appetite.

On the other hand, aerobic endurance training, particularly running, is linked with protein loss from muscle (partially induced by cortisol). Endurance trained individuals typically have a higher cortisol response, while resistance trained individuals have a higher testosterone response. Secretion of cortisol is elicited at exercise intensities between 80% and 90% of VO₂ max, which means that in this case, we’re not necessarily describing recreational exercise — we’re referring to endurance training.

Time of day and time of eating

The degree of cortisol release during high intensity exercise depends in part on the time of day and the timing of meals. When exercise is performed during a time of already high cortisol levels (for example, in the morning), it doesn’t increase above already elevated levels.

Cortisol secretion displays 7 to 15 spontaneous or meal-associated “pulses” throughout the day.

Cortisol circadian rhythms are closely coupled to the sleep-wake cycle. Peak cortisol release occurs between 7 and 9 in the morning, the time of dark-light transition.

Changes in cortisol over a 24-hour period

The physiological environment

Cortisol causes atrophy in muscle (mainly fast twitch type 2) and bone. The anabolic effects of testosterone and insulin oppose cortisol’s catabolic effects.

The acute increases in cortisol following exercise also stimulate acute inflammatory response mechanisms involved with tissue remodeling. In the short term, this is a necessary response that helps with repairing damage produced by training. Only long-term cortisol elevations seem to be responsible for adverse catabolic effects.

Stress (both psychological and physical) can result in the “alarm reaction.” If stress is ongoing, this can cause enlarged adrenal glands and atrophied lymphatic organs. When adrenals enlarge, they can produce excessive cortisol; when lymphatic organs shrink, they create fewer white blood cells. The immunosuppressive effects of intense exercise have been attributed to high plasma cortisol concentrations that prevail after prolonged intense exercise.

For extra credit

• Excessive secretion of glucocorticoids produces a collection of symptoms called Cushing’s syndrome. One of the symptoms is a redistribution of body fat, known as lipodystrophy.
• Protein and carbohydrate consumption after exercise can offset the cortisol response.
• High blood levels of glucocorticoids can stimulate gastric acid and pepsin production and may exacerbate ulcers.
• Cortisol levels can be up to 50% higher in animals under stress if alone (ie socially isolated).
• Estradiol increases the binding protein for cortisol so that circumstances associated with increased (pregnancy) or decreased (exercise induced amenorrhea and menopause) estradiol alters the amount of circulating free cortisol and its actions.
• Exercising in a depleted state can result in high levels of gluconeogenesis (protein breakdown).

Summary and recommendations

• Take regular, planned breaks from intense training
• Consume enough calories from non-processed foods to prevent depletion
• Get 7-9 hours of sleep per night to decrease stress and cortisol release
• Consume carbohydrates and protein after exercise sessions
• Don’t isolate yourself – spend time with friends and family
• Regularly participate in a stress-relieving activity like mild yoga or meditation
• Avoid excessive amounts of intense aerobic endurance training (unless training for endurance event)

References

What is creatine?

Creatine is an amino acid derivative constructed from arginine, glycine and methionine. It is produced naturally by the body in the kidneys, liver, and pancreas at a rate of about 1-2 grams/day. Creatine can also be obtained from food (particularly red meat) and supplementation.

The uptake of creatine into muscle cells is an active process. 90-95% of creatine in the body is found in muscle.

Creatine is degraded into creatinine and excreted in the urine at a rate of around 2 grams/day.

Why is creatine so important?

The energy needs of brief, rapid and powerful movements lasting fewer than 10 seconds, such as a short sprint, are met by the phosphagen system. This system quickly replenishes the stores of adenosine triphosphate, or ATP, which provides energy to the working cells. Muscles have an existing amount of ATP hanging around ready for action, but only a little bit — enough for a few seconds. ATP is broken down by removing a phosphate, which turns it into adenosine diphosphate (two phosphates). To make more ATP, the muscles need to get the missing third phosphate from somewhere, quickly.

This is where creatine phosphate comes in. It takes one for the team by donating its phosphate so that ADP can become ATP again, and so you can finish that sprint.

Because creatine plays a major role in this system, more creatine means more potential ATP, which translates into improved performance on short-duration, high-intensity tasks. Because long-duration, low-intensity activities rely more on a different energy system, they are not typically enhanced by creatine — in other words, creatine will help a sprint but not a marathon.

Consuming creatine supplements can increase skeletal muscle free creatine (which makes up about 1/3) and phosphocreatine (which makes up about 2/3) concentrations. These are the naturally occurring energy pools that replenish ATP.

Uptake of creatine into muscle also has a cell volumizing effect by drawing water into the cell. Over the long term, this swelling may increase protein synthesis and glycogen storage.

What you should know

Creatine is taken as a supplement in the form of creatine monohydrate (mainly), because the phosphorylated creatine (creatine phosphate or phosphocreatine) does not pass through cell membranes.

Other forms of creatine supplements have not been heavily studied and may result in more of a by-product known as creatinine. A recent study found that “when compared to creatine monohydrate, creatine ethyl ester was not as effective at increasing serum and muscle creatine levels or in improving body composition, muscle mass, strength, and power.”

Creatine use can improve performance in high-intensity events (e.g., weight training, sprints, etc). Longer duration aerobic workouts may not benefit from regular creatine use.

When following high-dose creatine loading strategies, body mass can be increased by nearly 2 kg (over 4 lbs) in just 7 days. This is mainly due to increases in total body water. However, these rapid water gains are not necessarily associated with lower dose creatine use.

As previously mentioned, long-term use of creatine can stimulate muscle protein synthesis. Plus, when power and strength levels are enhanced, general muscular adaptation can occur indirectly.

The benefits of creatine supplementation may go beyond athletic performance: creatine may have neuro-protective effects on neurological diseases such as Huntington’s disease, Parkinson’s disease, amyotrophic lateral sclerosis (ALS, aka Lou Gehrig’s disease). More human trials are needed to confirm this.

For extra credit

Creatine appears to be safe to use while exercising in the heat.

Creatine does not appear to increase the risk of cramping or injury.

Combining caffeine with creatine shouldn’t negate its effects. (See Creatine Combinations)

Creatine supplementation may be even more beneficial in those on a plant-based diet, due to the lack of creatine consumption from food.

About 20 percent of creatine users are deemed “non-responders.” This may occur because they already have a high enough dietary intake of creatine from whole foods. Conversely, creatine supplementation may be even more beneficial for those on a plant-based diet, due to the lack of creatine consumption from food.

A standard omnivorous diet contains about 1 gram of creatine per day. Typically, additionally benefits occur with intakes of 3-5 grams per day.

Creatine supplementation may be more effective when combined with carbohydrates during the first few days of supplementation. This suggests that insulin may moderate its effects. However, after the first few days, carbohydrates may not be required.

Based on current data, long-term creatine supplementation does not result in adverse health effects.

Creatine supplementation may increase anterior compartment pressure in the lower leg so athletes may want to be careful with creatine supplementation if they’re prone to shin problems.

Summary and recommendations

If you decide to use a creatine supplement:

• Use the monohydrate form
• Consume 3-5 grams of creatine per day
• Dissolve the creatine in a warm beverage like green tea
• You can also take your creatine before and/or after workout sessions with your workout nutrition
• Take a break from creatine supplementation after using for 12-16 weeks

References

What are branched chain amino acids?

Amino acids are the building blocks of protein. Branched chain amino acids (BCAAs) are so called because of their structure, which includes a “side chain” of one carbon atom and three hydrogen atoms. There are three BCAAs: leucine, isoleucine, and valine. Of these, leucine is the most heavily researched, and appears to offer the biggest physiological benefit. (More on that below.)

For the science geeks, these hydrophobic (water-fearing) amino acids are referred to as “aliphatic” (from the Greek aleiphar, or oil), as their central carbon attaches to a branched non-cyclic, open carbon chain.

BCAAs provide the basis for protein synthesis and energy production (Harper AE et al 1984; Patti ME et al 1998; Xu G et al 1998; Anthony JC et al 2001). In fact, BCAAs can comprise up to one-third of muscle protein (Mero 1999). Because of their prevalence and involvement in protein synthesis and energy production, BCAAs are important to many metabolic processes.

However, if BCAAs are going to participate in these processes, they must be available to the body. This means we have to eat enough BCAAs, and at the right times, to enable such processes to occur.

Why is adequate BCAA intake so important?

The BCAAs are the only amino acids not degraded in the liver. All other amino acids are regulated by the gut and the liver before being circulated elsewhere in the body. However, BCAAs head directly into the bloodstream. This means that dietary intake of BCAAs directly influences plasma levels and concentrations in muscle tissue (Layman DK 2003). Interestingly, BCAAs are burned for energy (oxidized) during exercise, so they’re also an important exercise fuel.

Consuming BCAAs before training can increase uptake into muscle tissue (Mittleman KD et al 1998). This has many benefits:

1. BCAA supplementation may lower lactate levels after resistance training and improve muscular oxidation.
2. BCAAs may increase growth hormone (GH) circulation, which may be related to anabolic mechanisms causing muscle growth (De Palo EF et al 2001).
3. BCAA supplementation may decrease serum concentrations of the intramuscular enzymes creatine kinase and lactate dehydrogenase following prolonged exercise. This can decrease muscle damage and improve recovery (Coombes JS, McNaughton LR 2000).

Muscle is an important site of BCAA activity. There is an increased cell concentration and breakdown of BCAAs in muscle tissue (Layman DK 2003). BCAAs are continuously released from the liver and other internal organs to skeletal muscle so that the BCAAs can assist in maintaining blood sugar levels. Indeed, BCAAs may be responsible for up to 40% of blood sugar production during exercise (Ahlborg G et al 1974; Ruberman NB 1975; see also Layman DK 2003).

What you should know

Because BCAAs are so important to muscle tissue, and because they help maintain blood sugar levels, it’s important to get enough to support your workouts. Consuming a carbohydrate, protein, and amino acid beverage during and after training can induce an insulin response, which helps transport BCAAs into cells. However, availability of leucine is more important than insulin. Within the muscle cell there’s one particular regulatory pathway for protein synthesis that’s stimulated by insulin, but dependent on leucine (Anthony et al 2000). In other words, protein synthesis (and hence muscle rebuilding) depends on how much leucine is available. And since BCAA levels decline with exercise, it makes sense to supplement with them during and/or after workouts (Mero 1999).

Because it’s so important to have leucine available for protein synthesis, if you train in a fasted state, or don’t eat after exercise, you’re going to lose more protein than you rebuild. However, if you eat adequate BCAAs during this time, especially leucine, you’ll enhance protein synthesis.

For extra credit

For the body to make new proteins, it needs an estimated daily leucine intake of between 1 to 4 grams/day (FAO/WHO/UNU 1985). That minimum intake needs to be met before leucine will be able to impact the insulin signaling pathway. But that’s just a baseline. Actual metabolic use, especially by athletes and people doing heavy resistance training, may be upwards of 12 grams/day.

There is a theory that BCAAs can limit central fatigue with endurance athletes, but it doesn’t appear to be supported by current data.

BCAA content of foods (grams of amino acids/100 g of protein)

Whey protein isolate 26%
Milk protein 21%
Muscle protein 18%
Soy protein isolate 18%
Wheat protein 15%

Source: USDA Food Composition Tables

Summary and recommendations

BCAAs play an important role in:

• Synthesis of proteins in general
• Glucose homeostasis (i.e. keeping blood sugar levels constant)
• Direct regulation of muscle protein synthesis (via insulin signaling cascade)

BCAAs’ potential impact on the aforementioned processes depends upon availability and dietary intake.

Adequate consumption of BCAAs may help manage body fat, spare muscle mass, and regulate glucose/insulin balance.

How can you put this knowledge to use?

Try adding BCAAs into your workout drink at a rate of 5 g BCAA per hour of training.

During periods of lower calorie intake, try adding a BCAA supplement every 2-4 hours during the day.

References

What is glutamine?

Glutamine is the most abundant free amino acid in the human body, making up about 60% of the skeletal muscle amino acid pool. (For more on amino acids, see All About BCAAs and All About Protein sections.)

Glutamine is a conditionally essential amino acid, which means that normally our bodies don’t need it from our diet. Exogeneous glutamine (in other words, glutamine we supplement or consume in food) is essential only under certain conditions, which include stress, trauma, muscular dystrophy, and illness, which can decrease glutamine levels by up to 50% (in severe cases). Because glutamine is a precursor for the structural unit of DNA and RNA, rapidly dividing cells are most likely to suffer from a shortage.

When we aren’t experiencing stress, trauma, muscular dystrophy or illness, our body produces enough glutamine on its own to supply our needs. The major part of endogenously produced (in other words, stuff our body makes) glutamine comes from skeletal muscle. Vitamin B3 and B6 are necessary for the production of glutamine from glutamic acid.

Why is glutamine so important?

Glutamine is a vital fuel source for the intestines and immune system that helps to keep defenses up against microbes. By nourishing these cells, it maintains the integrity of the GI tract.

Since the immune system is necessary for recovery from stress, glutamine may help during intense bouts of training. It may play a role in:

• Normalizing growth hormone
• Promoting glucose uptake after workouts
• Enhancing the hydration state of a muscle
• Reducing acid buildup with exercise

Yet it doesn’t seem that exercise decreases glutamine concentrations enough to compromise regular immune functions. This makes sense, since those who consume adequate energy from their diet tend to have a high glutamine intake. However, some people whose training and diet causes physical stress may benefit, e.g. people who are eating less food than necessary to modify body composition (in other words, dieting) or people whose training is extremely strenuous (such as elite athletes).

What you should know about glutamine

Where to find it

Cabbage and beets contain high concentrations of glutamine. (Eastern European grandmothers everywhere, rejoice! You have one more reason to encourage your “too skinny” grandchildren to eat the buraczki, borscht and holubtsi!) Other food sources include fish, beans and dairy.

Glutamine supplementation and dose

Typically, the consumption of any solo amino acid in high doses may hinder the assimilation of other amino acids. High doses of single amino acids can also result in bloating and diarrhea since they have osmotic properties. Yet glutamine supplements appear to be absorbed adequately and don’t create GI distress.

Glutamine supplementation has become routine to promote gut health in those with GI disorders, or those with HIV/AIDS, cancer, and other severe illnesses. Because glutamine has a rapid turnover rate, even high amounts (up to 30 grams each day) can be given without side effects. Most people will have a normalized plasma glutamine concentration by adding 20-25 grams over a 24 hour period.

In studies, glutamine supplement dosages have varied, including:

• 18 to 30 grams per day, by mouth
• 10 grams three times per day, by mouth
• 0.6 grams per kg of body weight per day (thus a 100 kg/220 lb person would consume 60 g daily)
• 14 grams of glutamine per day in combination with arginine and HMB for up to 24 weeks

Glutamine side effects and long-term use

There is little data regarding long-term usage (more than a few weeks) of glutamine supplements. No reported adverse effects have been attributed to short-term supplementation at less than 30 grams per day. Still, in some studies using high-dose intravenous administration of glutamine, patients developed elevated liver enzymes (indicating liver stress).

Other groups at risk:

• Those with diabetes should use caution when supplementing with glutamine because they tend to metabolize glutamine abnormally.
• Those who are sensitive to MSG (monosodium glutamate) may want to avoid glutamine supplements, due to glutamate inter-conversion.
• Those with epilepsy or bipolar disorder should be extremely cautious if considering glutamine and discuss it with their doctor first. Many anti-seizure medications work to block glutamate stimulation in the brain. And since the body metabolizes glutamine to glutamate, glutamine may interact negatively with anti-seizure medication.

Summary

Will it harm you in doses of less than 30 grams per day? Probably not.

If all of your bases are covered with nutrition, exercise and recovery, and you have the money to spend each month on more supplements, then adding glutamine is good. If you are undergoing a period of food restriction, then glutamine supplementation may improve nitrogen retention, decrease infection, and promote recovery from illness. Other situations that may benefit from glutamine supplementation include GI disorders, HIV/AIDS, and cancer.

Extra credit

Glutamine is a precursor for arginine.

A supplement blend containing glutamine has been shown to lower body fat, increase muscle mass, and increase strength when combined with 12 weeks of resistance training.

References