Fast Twitch Muscle Fibers: Anaerobic
Not all muscles are the same. Muscle fibers can be loosely distinguished on whether they mediate fast or slow movements. Fast muscle fibers are also classified as Anaerobic since they are able to produce force without the assistance of oxygen. This oxygen-independence has an additional advantage. Since anaerobic muscle fibers are not limited by oxygen availability they are fast to execute. On the downside, however, they do tire rapidly.
Fast (Anaerobic) muscle fibers are called into play when we undertake explosive movements. Heavy lifting and sprinting are examples of exercises recruiting fast muscle fibers. Have you ever thought it strange that we are taught to hold our breath during the execution phase of the bench press? The reason for this is simply that oxygen isn't required to perform the lift and breathing only gets in the way of the task at hand.
On the other hand, maximal efforts are usually brief (10 seconds) due to the high fatigability of fast muscle fibers. Fast muscle fibers do require oxygen in order to recuperate. Thus, we breathe harder following all-out efforts.
Slow Twitch Muscle Fibers: Aerobic
Slow muscle fibers, on the other hand, are Aerobic. Aerobic muscle fibers do require oxygen to generate force. Oxygen availability, however, will limit how rapidly aerobic muscle fibers respond, which is, as the name implies, relatively slow. Aerobic muscle fibers will therefore provide lower levels of force, but will do so for as long as sufficient oxygen is available.
Marathon runners rely heavily on slow muscle fibers. Obviously, you wouldn't want to run a marathon while holding your breath. To summarize, the reason we can only sprint briefly, while we can walk for hours, is that these activities call into action different types of muscle fibers.
Sprinting calls into play fast (anaerobic) muscle fibers. Fast muscle fibers generate brief, explosive forces. On the other hand, slow (aerobic) muscle fibers are used for lower intensity movements lasting more than a few seconds. The amount of force generated by slow muscle fiber is much less, but can only be maintained for as long as our breathing allows.
Creatine & Fast Muscle Fibers
Just as not all muscle fibers are the same, creatine doesn't influence all muscle types in the same manner. Creatine preferentially increases the work output of fast muscle fibers; the ones that don't require oxygen to generate force. This would be noticed as an increase in sprint performance, while our jogging performance would go mostly unchanged. We are actually feeding fast muscle fibers by supplementing with creatine!
Protein Synthesis & Muscle Growth
It is natural that some muscle damage occurs during exercise. In fact, this exercise-induced muscle damage is essential for subsequent muscle growth. Simply speaking, we literally breakdown our muscles during exercise and rebuild them during recovery. Whether our muscle mass increases, or decreases, depends on which of these two processes is greater.
The Difference Between Using Alcohol Or Not?
For example, if muscle breakdown exceeds muscle regrowth, then we lose muscle mass. Protein synthesis, or the production of new muscle proteins, is an essential part of this rebuilding process following exercise.
Alcohol & Muscle Growth
Importantly for today's discussion, it appears that alcohol use inhibits muscular protein synthesis. This inhibitory effect of alcohol is most pronounced in fast muscle fibers, especially after prolonged alcohol use.
The scenario would be detrimental for any athlete trying to gain muscle mass and strength through training. After all, isn't the goal of training to increase muscle protein synthesis? The problem is that creatine allows us to work harder, which is generally a good thing.
However, this would also mean that muscle recovery is more critical while supplementing with creatine. As alcohol consumption inhibits protein synthesis, a potentially fruitless situation may arise by mixing the two. That is, creatine and alcohol.
Finally, there is also some indication that creatine also stimulates protein synthesis. This effect may underlie part of creatine's benefit. If so, then alcohol consumption would offset this benefit of creatine as well.
Note: Keep in mind these important points:
- Alcohol inhibits protein synthesis in fast muscle fibers. Protein synthesis is essential for muscle growth and development. Protein synthesis is important for muscle recovery.
- Creatine increases the work output of fast muscle fibers. Thus, fast muscle recovery is more critical during supplementation. Creatine may increase protein synthesis as part of its benefit.
- Alcohol may be particularly damaging during creatine supplementation.
Alcohol & Anabolic Hormones
Anabolic means to promote growth. Alcohol adversely influences the anabolic properties of two of our principal growth promoting hormones, Insulin and Growth Hormone. Furthermore, most of the anabolic effects initiated by Growth Hormone are mediated by Insulin-like Growth Factor-1 (IGF-1). These hormones are essential for inducing muscle protein synthesis after exercise and are also thought to interact with creatine.
Alcohol causes insulin-resistance as well as hinders the release of Growth Hormone from the brain. Chronic alcohol consumption also reduces our IGF-1 levels. These combined effects will slow muscle development and mitigate our response to creatine.
Finally, Growth Hormone secretion is most important during puberty, when we are growing most rapidly. Anything that interferes with this normal surge in Growth Hormone might have serious developmental consequences. Therefore, adolescent athletes are strongly discouraged from consuming alcohol.
Although possibly having no direct effects on creatine energy production per se, alcohol creates a biochemical environment that could undermine the benefits afforded by creatine. Alcohol decreases muscle protein synthesis, causes insulin-resistance and interferes with the release of Growth Hormone (and, hence, IGF-1) following exercise. All of which would mitigate creatine's effect.
Don't misconstrue my message. This is not a crusade against alcohol consumption. In fact, an occasional glass of red wine has been shown to possess healthful qualities. In my opinion nothing beats a good Bordeaux.
However, if you're serious about making gains in strength and mass, then maybe you should abstain from alcohol, especially immediately before bed and after exercise. This precaution is especially important if you are below 20 years of age, when Growth Hormone release is most necessary for normal growth and development. In any case, moderation is always the best policy.
- Preedy VR, Patel VB, Reilly ME, Richardson PJ, Falkous G, Mantle D. (August 1999) Oxidants, antioxidants and alcohol: implications for skeletal and cardiac muscle. Frontiers in Bioscience Volume 1:4: pages e58-e66.
About The Author:
Dr. Alfredo Franco-ObregÃ³n has had over 20 years of in depth research experience in major laboratories world-wide. His major scientific interest is the understanding of the cellular mechanisms that lead to muscle cell death.
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