Slow-Twitch Muscle Fibers

[mikeyg51]

So, I was reading this article by Shane Glease on Bodybuilding.com because I wanted to learn more about slow-twitch muscle fibers and the optimum number of reps to do for, say, side delts; however, it states that 25-50 reps are excellent for slow-twitch fibers! I know the basics of slow vs fast fibers, but I am curious to learn of what you guys do to try to target the different types....

[WidowMaker]

Fast and Slow Twitch Muscle FibersDoes muscle type determine sports ability?By Elizabeth Quinn (http://sportsmedicine.about.com/bio/Elizabeth-Quinn-3502.htm), About.com Guide
Updated September 27, 2011
About.com Health's Disease and Condition content is reviewed by the Medical Review Board (http://www.about.com/health/review.htm)




[/URL]


Are you a better sprinter or distance runner? Many people believe that having more fast and slow twitch muscle fibers may determine what sports athletes excel at and how they respond to training.Skeletal muscle is made up of bundles of individual muscle fibers called myocytes. Each myocyte contains many myofibrils, which are strands of proteins (actin and myosin) that can grab on to each other and pull. This shortens the muscle and causes muscle contraction.
It is generally accepted that muscle fiber types can be broken down into two main types:slow twitch (Type I) muscle fibers and fast twitch (Type II) muscle fibers. Fast twitch fibers can be further categorized into Type IIa and Type IIbfibers.
These distinctions seem to influence how muscles respond to training and physical activity, and each fiber type is unique in its ability to contract in a certain way. Human muscles contain a genetically determined mixture of both slow and fast fiber types. On average, we have about 50 percent slow twitch and 50 percent fast twitch fibers in most of the muscles used for movement.
Slow Twitch (Type I)
The slow muscles are more efficient at using oxygen to generate more fuel (known as ATP) for continuous, extended muscle contractions over a long time. They fire more slowly than fast twitch fibers and can go for a long time before they fatigue. Therefore, slow twitch fibers are great at helping athletes run marathons and bicycle for hours.
[URL="http://sportsmedicine.about.com/od/anatomyandphysiology/a/musclefatigue.htm"]What Causes Muscle Fatigue? (http://googleads.g.doubleclick.net/aclk?sa=L&ai=BXKiK2q1cT8XkOdP62gWi2viCAeTBl5oDtJCV-VHAjbcB0PAzEAUYBSCb0agGKAk4AFCy76_7BWDJxr2H4KOAErI BGHNwb3J0c21lZGljaW5lLmFib3V0LmNvbcgBAdoBTWh0dHA6L y9zcG9ydHNtZWRpY2luZS5hYm91dC5jb20vb2QvYW5hdG9teWF uZHBoeXNpb2xvZ3kvYS9NdXNjbGVGaWJlclR5cGUuaHRtgAIBq AMBuAMB6ANe6AOUBugDygn1AwAMAID1AwAAABA&num=5&sig=AOD64_2nMs729pPvMaZzKWm8TAMsPzqHaA&client=ca-about-health_js&adurl=http://fibromanagementnet.com/diagnose.php%3Faljhh%3Dmuscle%2520fatigue%7C%7Cc%2 6e%3Ddisplaynetworkfibro)
Fast Twitch (Type II)
Because fast twitch fibers use anaerobic (http://adam.about.net/encyclopedia/Anaerobic.htm) metabolism to create fuel, they are much better at generating short bursts of strength or speed than slow muscles. However, they fatigue more quickly. Fast twitch fibers generally produce the same amount of force per contraction as slow muscles, but they get their name because they are able to fire more rapidly. Having more fast twitch fibers can be an asset to a sprinter since she needs to quickly generate a lot of force.
Type IIa Fibers
These fast twitch muscle fibers are also known as intermediate fast-twitch fibers. They can use both aerobic (http://adam.about.net/encyclopedia/Aerobic.htm)and anaerobic metabolism almost equally to create energy. In this way, they are a combination of Type I and Type II muscle fibers.
Type IIb Fibers
These fast twitch fibers use anaerobic metabolism to create energy and are the "classic" fast twitch muscle fibers that excel at producing quick, powerful bursts of speed. This muscle fiber has the highest rate of contraction (rapid firing) of all the muscle fiber types, but it also has a much faster rate of fatigue and can't last as long before it needs rest.
Fiber Type and Performance
Our muscle fiber type may influence what sports we are naturally good at or whether we are fast or strong. Olympic athletes tend to fall into sports that match their genetic makeup. Olympic sprinters have been shown to possess about 80 percent fast twitch fibers, while those who excel in marathons tend to have 80 percent slow twitch fibers.
Are Athletes Born or Built? (http://sportsmedicine.about.com/od/anatomyandphysiology/a/genetics.htm)
Can Training Change Fiber Type?
This is not entirely understood, and research is still looking at that question. There is some evidence showing that human skeletal muscle may switch fiber types from "fast" to "slow" due to training.
These studies and journal articles offer more insight on muscle fiber research:
High-Intensity Training and Changes in Muscle Fiber (http://www.springerlink.com/content/1137px7x66667132/)
Nature vs. Nurture: Can Exercise Really Alter Fiber Type Composition? (http://www.the-aps.org/publications/classics/articles/ingalls.pdf)
Effects of Endurance Training on Muscle Fiber (http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1280565)
What can I do to improve my performance?
Keep in mind that genetic differences may be dramatic at the elite levels of athletic competition. But following the principles of conditioning (http://sportsmedicine.about.com/cs/conditioning/a/aa050901a.htm) can dramatically improve personal performance of a typical athlete.
With consistent endurance training, muscle fibers can develop more and improve their ability to cope with and adapt to the stress of exercise.
Is fiber type the number one factor that makes an elite athlete elite?Fiber type is part of a great athlete's success, but it alone is a poor predictor of performance. There are many other factors that go into determining athleticism, including mental preparedness (http://sportsmedicine.about.com/od/sportspsychology/Sports_Psychology.htm), proper nutrition (http://sportsmedicine.about.com/od/sportsnutrition/Sports_Nutrition.htm) and hydration (http://sportsmedicine.about.com/od/hydrationandfluid/Drinking_Hydrating_for_Exercise.htm), getting enough rest (http://sportsmedicine.about.com/od/sampleworkouts/a/RestandRecovery.htm), and having appropriate equipment and conditioning (http://sportsmedicine.about.com/od/sampleworkouts/Exercises_and_Workouts.htm).Sources:
Andersen, JL; Schjerling, P; Saltin, B. Scientific American. "Muscle, Genes and Athletic Performance" 9/2000. Page 49

McArdle, W.D., Katch, F.I. & Katch,V.L. (1996). Exercise physiology : Energy, nutrition and human performance

Lieber, R.L. (1992). Skeletal muscle structure and function : Implications for rehabilitation and sports medicine. Baltimore : Williams & Wilkins.

Andersen, JL; Schjerling, P; Saltin, B. Muscle, Genes and Athletic Performance. Scientific American. 9/2000

Thayer R, Collins J, Noble EG, Taylor AW. A decade of aerobic endurance training: histological evidence for fibre type transformation. Journal of Sports Medicine & Phys Fitness. 2000 Dec;40(4).

[WidowMaker]

Even though I busted my ass through the years for the size and strength I have. Some people have mere fast or slow twitch muscle fibers that will determine the beginning of their sports ability.
Now with that being said I had to bust my ass in football and wrestling to keep up. But I never give up! Baseball was a lot easier for me in sports.
If you notice in my training journal i use a lot of hybrid training and not a "1" style training methodology.
This works best for me to recruit the muscles fibers need for my specific goal.
I study and plan my next cycles like putting together puzzle pieces for the big picture.
For my cardio I walk with Mary, use the elliptical trainer, going to be using our new (plate loaded) dog sled we got the other week, and Mary's Zumba dance vids.
O crap did I say that outloud, lol!

Anyways this is what works works for me and with my age and experience I have trained a lot of people with great success but I have had a few lazy asses that training was too much for them.
I keep a foundation of my training throughout my lifting but I'm always open to new techniques or strategies.

[rghtnow]

I found over the years that my body has responded well to both high and low rep training targeting both muscle fibers....I think everyone responds differently but it's my belief that you should try and incorporate both high and low reps into your training to keep your muscles constantly guessing and in the growth zone....our body's have this unique ability to adapt to any training method over time so constantly switching keeps the muscles from adapting....