Improving running performance is multi-faceted; the aim of this article is to focus on exercises related to fast twitch muscle fibers and explains a general overview of their function.
Fast-Twitch Muscle Fibers:
Type II fibers are involved in any activity that includes a quick explosive movement or the rapid development of power. Most common applicable example would be football players and track and field athletes. Type II fibers develop more power then Type I or slow twitch muscle fibers because the Type IIx fiber can contract 10 times faster than the Type I fiber. The more adept you become at recruiting your Type II fibers; the more power you can develop. This leads to faster sprint times and decreased mile times for more focused short distance runs.
Two Types of Fast-Twitch Muscle Fibers:
1) Type IIa (Fast Twitch, Oxidative-Glycolytic)
High 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 possess high numbers of Type IIa muscle fibers, and research suggests they play a big role in muscle size.
2) Type IIx (Fast Twitch, Non-Oxidative)
Low number of mitochondria
Large in diameter
Good for high-intensity, large-power output, such as track/field events and power lifting.
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 or growth of the Type II fibers, increasing their power output.
Help recruit, put them into applicable use of Type II fibers faster.
Change Type I fibers to Type II fibers.
Fast-Twitch Muscle Workouts:
1) Dumbbell reverse lunges with quick switches utilizing jumps:
Stand holding a pair of dumbbells at your sides, with your feet shoulder width apart.
Ensure you have at least a few feet of clearance behind you.
Start with your chest out, head up, and a slight bend in your knees.
Step backward with your right leg, landing on the ball of the foot, then bend both knees to lower yourself to the floor. (Make sure to step back far enough so your front knee is behind the toes at the bottom of the movement.) When your front thigh is parallel with the floor, extend your knees and hips to stand back up to the start position. Alternate legs with jumps or quick transitions every rep.
2) Box jumps w/ kettlebell:
Obtain a plyometric box between 12-36 inches, depending on your abilities.
Grab a kettlebell where you can do 8-12 repetitions rather quickly.
Ensure you have enough room to safely land and clear jumps. Preferably 5ft by 5ft.
Assume an athletic position, with your feet about shoulder-width apart, at a comfortable distance from the box. Start the box jump by quickly getting into a quarter squat while hinging at the hips to engage the hamstrings and gluteus. Place and keep your hands at the crest of the kettlebell, so both hands are holding the bell. Hold the kettlebell close to your chest, just below chin level. Then, forcefully extend your hips, swing your arms and push your feet though the floor to propel yourself onto the box. Focus on landing lightly on top of the box with your knees slightly above 90 degrees with your chest up. Hold for two to three seconds, stand tall, and step back down. Repeat.
3) Deadlift followed by a squat jumps
Set an Olympic straight bar on the ground and load it with appropriate weight.
Ensure your space is clear and that you have enough room to work.
Stand with feet slightly wider than shoulder-width apart, toes pointing straight ahead or slightly outward (no wider than 11 and 1 o’clock). The balls of the feet should line up under the bar. With knees slightly bent and hands gripping the bar slightly outside of legs, hinge forward from hips. With the bar close to shins, keep head up, eyes looking forward, chest out, and back flat. Inhale. Keeping the bar close to the body, exhale as you work to straighten the legs — drive through the heels, not the toes — and bring the weight up past knees. Keep core engaged throughout the entire movement (this helps protect the spine) and finish by thrusting the hips into alignment with the feet and squeezing your glutes. Maintaining a straight back, slowly hinge forward at the hips (allow knees to bend a little at the same time) and lower the bar back to the ground. That is one rep.
For the squat jumps, step back from your deadlifting bar, set your feet shoulder width apart. Lower yourself down to where hips / gluteus is loaded towards your rear. Bring your bottom to knee level and thrust straight up landing tall onto the toes then reset. Repeat.