So you want to be as strong as the Hulk, as fast as Flash and as awesome as Superman. The secret to unlocking that superhuman potential may lie within your muscles. Your muscle fibers have a lot of influence what you excel at, whether it's crushing long-distance marathons or finishing 100-meter sprints in the blink of an eye.
Muscle fibers are classified into two main groups Type I (slow twitch) and Type II (fast twitch). Type II fibers are further broken down into subclasses IIa, fast twitch oxidative-glycolytic) and IIx, fast-twitch non-oxidative.
Type I (Slow Twitch, Oxidative)
- Slow contracting
- Slow fatiguing
- Small diameter
- High number of mitochondria
- High oxidative capacity (using fat stores as energy)
- Good for low intensity prolonged activities such as maintaining posture and running long distances
Type IIa (Fast Twitch, Oxidative-Glycolytic)
- Good number of mitochondria
- Can use both fat stores and glycogen stores for energy
- Resistant to fatigue and recover quickly
- Good for fast, repetitive, low-intensity activity. Bodybuilders posses high numbers of Type IIa muscle fibers, and research suggests they play a big role in muscle size.
Type IIx (Fast Twitch, Non-Oxidative)
- Low number of mitochondria
- Large in diameter
- Fast fatiguing
- Good for high-intensity, large-power output, such as field events and power lifting.
Role of Fast-Twitch Fibers in Sports
Type II fibers are involved in any activity that includes a quick explosive movement or the rapid development of power. If you play any field sport (shot put, high jump, etc.), football, hockey or sports that don't involve long, slow repetitive movements, it would be in your best interest to develop your fast-twitch muscle fibers.
The quicker you can recruit your Type II fibers, the more power you can develop. This will give you faster sprint times and help you lift heavier weights and jump higher.
The biggest reason Type II fibers develop more power then Type I is because the Type IIx fiber can contract 10 times faster than the Type I fiber.
Can People Be Born With More Type II Muscle Fibers?
No two people are built the same. Just as people are born with different bone structures and different levels of hormones, the same is true for muscle fibers. You may be better suited for running long distances (Type I) or explosive bursts of power (Type IIx), or you may be in the middle (Type IIa).
Some people are born with more fast-twitch muscle fibers than others. But cheer up—with training, you can change your ratio of fast-twitch to slow-twitch muscle fibers.
Training for Fast-Twitch Muscle Fibers
There are a number of ways to increase your ratio of Type II fibers—heavy strength training, speed training, plyometric training and Olympic lift training. Training does a few things:
- Hypertrophy of the Type II fibers, increasing their power output.
- Help recruit Type II fibers faster.
- Change Type I fibers to Type II fibers.
Strength training and speed training can be very effective in developing maximum force. Lifting a heavy weight with slow acceleration will develop maximum force, but you can also achieve maximum force by lifting a lighter weight with fast acceleration. Heavy Squats, Deadlifts and Bench Presses are good ways to increase Type II fibers. So is running sprints, agility drills and med ball training.
Plyometric training and Olympic lifting are also effective fast-twitch fiber recruiters. They do it by using the stretch-shortening cycle (SSC), which involves a pre-stretch of the muscle followed by a rapid contraction of the same muscle, resulting in the production of maximum force. Effective exercises include Vertical Jumps, Broad Jumps, Power Cleans, Power Snatches and Depth Jumps.
Long-distance endurance training (running and cycling) and lifting lighter weights for high reps will develop slow-twitch muscle fibers. Unless you want to decrease your fast-twitch muscle fibers, you should limit the amount of endurance training, allotting time for it separate from your strength and power training.
Fast-Twitch Muscle Workout Routine
Uses the whole body to develop power.
- Start with your feet under your hips.
- Keep your weight close to your body. Don't let it drift away.
- Start with light weights and grove the pattern.
Sets/Reps: 4-6x1-5, rest 90 seconds to 3 minutes
Med Ball Cross Behind Side Toss
Med Ball exercises are another great way to develop max power. They are also easier to learn than Olympic lifts. The Med Ball Cross Behind Side Toss is an excellent exercise for developing rotational power for sports like baseball, golf and shot put. You start with one of your shoulders facing a wall. The med ball starts at your back hip. You then cross your back leg behind your front leg, step forward with your front leg and step through with your back leg. When you finish, your hips face the wall.
- Force is created from the hips. Think about rotating your hips as fast as you can, not so much about throwing the ball.
- Keep your core tight.
- Load your back leg to start and finish with weight on your front leg.
Sets/Reps: 3-6x3-6, rest 90 seconds to 3 minutes
Perform a heavy lift at 85% to 95% of your 1 RM, followed by an explosive movement. Another way to look at it, as Russian researcher Yuri Verkhoshansky puts it, is to visualize lifting a can half full of water, but thinking it is full. The end result: lifting the can of water twice as fast. There are a lot of ways to set up the PAP Complex:
- Heavy Bench Press followed by a Med Ball Chest Pass or Shot Put throw
- Heavy Squats followed by a Vertical Jump
- Heavy Deadlift followed by a Broad Jump
- Heavy Sled Drag followed by Sprints
- Not for beginner athletes.
- May be best used for a one-time max test (Vertical Jump or Sprint)
- May work better for people with a higher ratio of Type II muscle fibers.
Sets/Reps: 4-6x3-5 (each exercise), rest 90 seconds to 3 minutes (between strength and power exercise)
Verkhoshansky, Y. V. , and M. C. Siff. Supertraining. Supertraining Institute, 2009. print.
- STACK Science: Developing Slow- and Fast-Twitch Muscle Fibers
- NaVorro Bowman Fast-Twitch Upper-Body Superset
- 3 Common Romanian Deadlift Mistakes
- Calf Exercises That Work