Alcohol (ethyl alcohol or ethanol), one of the world's oldest, most widely-used drugs, has many effects on the body. Some are positive, but most negative. Historically, alcohol has been blamed for many of the world's tragedies and problems, from the fall of the Roman Empire (What's Your Poison; 1997) (1) to the disbanding of many families. Ironically, it is made from relatively innocuous substances.
Fermented grain, fruit juice and honey have been used to make alcohol for thousands of years. Alcohol's use spans nationalities and demographics. It serves to relax and provide a source of enjoyment. It has even been shown to have some salutary effects, such as a blood thinning action beneficial to the cardiovascular system, in addition to the aforementioned social and relaxation aspects.
However, the doses required in these instances are very minimal (1-2 glasses in most cases), and anything beyond this more than outweighs any potential benefits. This is partly because alcohol is classed as a central nervous system depressant, causing the brain to relax and inhibitions to decrease.
One's rational thought, emotional status, judgement, speech and muscle coordination are adversely affected through alcohol consumption. In extreme cases it can cause coma and death. Alcohol is specifically detrimental to bodybuilders, or any athlete, in that it can interfere with recovery, protein synthesis, hydration, motivation, and nutrient intake. Its financial cost is a burden for anyone who buys it.
A review of the research will show that alcohol is poisonous to every organ in the body and will adversely affect everyone who engages in its use to some extent (1, 6, 7, 8). This article is not intended to dissuade people from using alcohol moderately, for recreational purposes, but will point out, from an athlete and a researcher's point of view, its significant shortcomings. Cheers.
Ethyl alcohol is a very small molecule, soluble in lipid and water solutions. It is metabolized primarily by the liver, where an enzyme called alcohol dehydrogenase breaks the alcohol down into acetaldehyde, which is further broken down into acetate.
Acetate is metabolized into carbon dioxide and water, which is excreted. Alcohol is absorbed rapidly from the small intestine (80%) and stomach (20%), before any other nutrients are digested.
These properties ensure that alcohol gets into the bloodstream and crosses the blood-brain barrier easily. Hence alcohol's instantaneous effect on thought processes. In fact, alcohol has a number of detrimental effects on the brain, two of which, central to the scope of this article, will be discussed first.
Alcohol, once it crosses the blood-brain barrier, inebriates the cerebral cortex (the part of the brain responsible for executive functions such as rational thought). It works its way down to the limbic system. It won't however affect the limbic system. This turns out to be a problem, because the limbic system, being the most primitive part of the brain, then takes over the
role of rational thought.
This is problematic because the limbic system is entirely emotional, and one then begins to think with their emotions rather than the rational area of their brain (the cerebral cortex). A surprisingly small amount of alcohol will have an instant effect on one's ability to control their emotions, and their judgement as a result. A comparatively large amount of alcohol and one might become violent or completely out of control in other respects.
As mentioned, alcohol is also a depressant. It's depressant effects result from increased transmission of the GABA systems (2). In other words, alcohol consumption creates a demand for more GABA. GABA is a neurotransmitter responsible for restricting, or depressing the excitability of our brain. Glutamate is the Neurotransmitter that has the opposite effect; it is responsible for brain excitability and can be increased through the intake of various stimulants. It now gets a bit complex.
The post synaptic receptors (the receptors of one brain cell that receive a message from another brain cell) for GABA, GABA-A, then become stimulated and respond by hyperpolarising the cell membrane and reducing the chance of an action potential occurring. An action potential is an electrical charge propagated through a neuron which causes that neuron to become stimulated. It gets worse.
Over time, if a sufficient amount of alcohol is consumed, the GABA receptors become accustomed to a certain amount of alcohol and more is required to get the same depressing and intoxicating effect. In short, tolerance occurs. With more and more alcohol the potential for the GABA receptor to function improperly increases. This may result in hyperexcitability causing, anxiety, tremors, disorientation, and hallucinations when one is not drinking.
This is alcohol at its destructive extreme.
In addition to alcohol's destructive effects at the time of ingestion, it can also cause neural tissue death when its consumption is stopped. As explained, GABA (a inhibitory neurotransmitter) binds to its GABA-A receptor following alcohol intake. When this happens, a chloride channel is opened and extracellular chloride moves into a intracellular compartment on the receptor. The neuron is hyperpolarized as a result and excitatory postsynaptic potentials (EPSPs) cannot occur, as mentioned.
The main point here is that alcohol facilitates the ability of GABA to open chloride channels. With greater (chronic) use of alcohol the neuron may become entirely dependant on alcohol for its GABA function in the long term. However, at the time of chlorides uptake another process, this time involving the glutamine (excitatory neurotransmitter) receptors, causes further problems.
The glutamate system is up-regulated with alcohol withdrawal and calcium-channel activity is stimulated. Calcium is released directly onto the post synaptic neuron (calcium influx) in large amounts and neural death occurs. This happens particularly after binge sessions that occur on a regular basis.
Implications For Athletes
Alcohol is particularly detrimental for athletes. It interferes with many of the processes so vital to success (3,5). Focus, performance, recovery and rebuilding are all affected. Given that alcohol's effects can linger for days, an athlete would be wise to refrain from its use when competing.
Although alcohol is absorbed rapidly it is metabolized very slowly and its effects may still impact athletic performance up to 48 hours after the last drink.
Assuming the athlete is performing within 48 hours of its consumption, as little as two to three standard drinks can directly:
- Decrease strength
- Impair reaction time
- Impair balance and eye/hand coordination
- Impair fine motor and gross motor coordination
- Increase fatigue: Liver function is significantly impacted following the ingestion of alcohol. Up to 48 hours after the last drink the liver may still be metabolizing alcohol at the expense of glycogen (metabolized carbohydrate).
Given that glycogen is vital for most of the body's cellular functions, body fatigue, cognitive decline and loss of strength will result when it cannot be used efficiently. Reaction time, balance, coordination are also impacted by this process in addition to the direct aforementioned neurochemical effects alcohol has on the brain.
- Interfere with body temperature regulation
- Cause dehydration: Alcohol has an impact on kidney function, which interferes with the regulation of electrolytes and fluids in the body (7). Cellular waste removal and nutrient supply are the main functions of fluid and electrolytes, which are controlled through kidney function.
The kidneys filter large amounts of water from many parts of the body, including the brain, to break down alcohol. This causes dehydration and can cripple an athlete's performance.
- Deplete aerobic capacity and negatively impact endurance for up to 48 hours after the last drink
- Impact cellular repair: Protein metabolism is negatively impacted when alcohol is in the system. This has obvious implications for muscle repair.
- Impacts the cardiovascular system: Alcohol consumption raises blood pressure and this can result in the heart having to work harder to pump blood through the body (8). An abnormally fast heart beat (tachycardia) can also result from alcohol consumption. Further, alcohol increases the synthesis of cholesterol and this can increase the risk of heart disease.
- Disrupt sleep: Alcohol significantly interferes with restful sleep (4). It can make falling to sleep easier to begin with due to its sedative effects but the quality of sleep (particularly rapid eye movement) will be disturbed.
- Cause vitamin and mineral depletion: Vitamins and minerals so necessary for our health have their absorption interfered with, while the body's own supply is slowly depleted, when alcohol is consumed. Even one or two drinks per day (supposedly the "recommended" amount) can have this effect. B vitamins, which have important enzymatic and metabolic functions are depleted extra rapidly (8).
This deleteriously effects the heart, liver, thyroid and kidneys. Vitamin A is also depleted and this interferes with the body's ability to fight disease. Vitamin C depletion makes one susceptible to anemia. Also, when alcohol is ingested the body excretes calcium at twice the normal rate, thus impacting on bone growth and wound healing.
- Cause cognitive impairment: cognitive impairment (disruption of thought processes and brain damage) occur through a number of mechanisms (6,7). Alcohol related sleep disruption contributes to the insufficient restoration of one's neural processes. The effects of GABA-A stimulation, as explained, have been shown to contribute to neural death.
Lack of glycogen to the brain, as a result of alcohol metabolism, causes slow, disoriented, thinking. These are just some factors. There are many more. The implications of cognitive impairment are severe for athletes: loss of motivation, focus and desire in addition to lessened perspicacity and even neuromuscular response.
The effects outlined here are just some of the more obvious ones. There are many others, and it would probably take a book to outline and explain them in sufficient detail.
Even though alcohol will greatly impact performance 25-to-48 hours after the last drink, it has longer-lasting, more indirect, effects. The reduction in quality of training and sleep in the period after its consumption, may cause a reduction in performance over the days following this period.
So it is probably best to stay away from alcohol completely when training and competing to win. Indeed, the only real way to avoid alcohol's effects is to refrain from its use completely.
- What's Your Poison.(1997). [On line]
- Aguayo LG. Ethanol potentiates the GABAA activates Cl- currents in mouse hippocampal and cortical neurons. Eur J Pharmacol 1990;187:127-130.
- Bloomfield, J. Fricker, P.A. & Fitch, K.D.(1992). Textbook of Science and Medicine in Sport. Blackwell Scientific Publications: Australia.
- Walsh J K. Sedative effects of ethanol at night. Journal of Study on Alcohol, 1991, 6, pp.
- Burke, L.(1992). The Complete Guide to Food for Sports Performance. Allen and Unwin: Australia.
- Dodes. L. M.(2002).The Heart of Addiction: A New Approach to Understanding and Managing Alcoholism and Other Addictive Behaviors: Quill, USA.
- Hunt WA. Are binge drinkers more at risk of developing brain damage? Alcohol 1993;10:559-561.
- Science in Africa.(2004). Alcohol and the Inevitable Hangover From Over Consumption. [On line] http://www.scienceinafrica.co.za/2001/december/drinks.htm
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