Fast Twitch

Hayai [速い] Keiren [けいれん]

We have either/or slow twitch muscularity or fast twitch. Most develop a balance of both abilities that allows for strength in movement which tends to be slow and fast twitch uses the muscles twitching ability for speed in movement. 

Fast-twitch muscle fibers contract quickly and help you perform fast, high-intensity activities for short periods, like sprinting, jumping jacks, box jumping, and weightlifting and strength-training workouts. Fast-twitch muscles are a large proportion of the small muscles in hands and eyes for rapid movement.

https://www.masterclass.com/articles/fast-twitch-vs-slow-twitch

Slow-twitch, or Type I muscle fibers, are skeletal muscle fibers that slowly contract. Slow-twitch muscle fibers support everyday actions, like standing from a seated position and maintaining normal posture. In fitness and exercise, slow-twitch muscle fibers are necessary for endurance athletes such as marathon runners, long-distance runners, swimmers, and cyclists. Muscle groups like the erector spinae in the lower back and soleus muscles in the legs have a high concentration of slow-twitch muscle fibers.

Skeletal muscles are made up of a combination of slow-twitch and fast-twitch muscle fibers, but in different proportions. Differences between these two types of skeletal muscle fibers include:

• Performance: Fast-twitch muscle fibers are faster acting, but tire more quickly in comparison to slow-twitch muscle fibers.
• Energy: Fast-twitch muscle fibers produce small amounts of energy rapidly, which works best for HIIT exercises. Slow-twitch muscles slowly produce larger amounts of energy, supporting endurance activities, like long-distance running.
• Physiological: Slow-twitch muscle fibers have more blood vessels and capillaries, so they are more efficient in energy usage in comparison to fast-twitch fibers.
• Oxygen: Fast-twitch muscles are relatively anaerobic, meaning they use little to no oxygen, and instead rely on different sources of bodily energy, such as glucose, which they use to make adenosine triphosphate (ATP). ATP is an essential chemical, present in all living organisms, that acts as a kind of energy shuttle within the cell, making activities possible, such as movement. Type IIA fast-twitch muscles are technically glycolytic, meaning they use oxygen and glucose as fuel. Type IIB, the fastest and most forceful, but also the least efficient, have low oxidative capacity and high myosin ATPase activity (they act very quickly but also tire quickly). Slow-twitch muscle fibers are aerobic and have higher concentrations of mitochondria and myoglobin, proteins that bind oxygen.
• Fast-twitch muscle fibers: For building fast-twitch muscle mass and strength, focus on high-intensity, low-duration exercises. If training with weights, complete lower reps as fast as you safely can. Uphill sprints such as stair climbing are great for building this type of muscle, as are box jumps, kettlebell exercises, and jump squats.

What Are Fast-Twitch Muscle Fibers?

Fast-twitch muscle fibers, known as Type II muscles, are a category of skeletal muscle fibers in the human body. Muscles consist of fibers, and electric impulses from the brain stimulate the fibers to produce movement in the form of contractions. Fast-twitch muscle fibers contract quickly and help you perform fast, high-intensity activities for short periods, like sprinting, jumping jacks, box jumping, and weightlifting and strength-training workouts. Fast-twitch muscles are a large proportion of the small muscles in hands and eyes for rapid movement.

There are two subcategories of fast-twitch muscle fibers: Type IIA and Type IIB or Type IIX. Type IIB creates the fastest and most powerful muscle contractions, but these are also the least efficient as they tire out the fastest. Type IIA are quicker to recover but not as vigorous as Type IIB.

To get fast twitch muscles for striking and kicking it requires repetitive consistent efforts with little or no weights. Moving as fast as possible using a positive relaxed form of movement as tension in the muscles slows the movement and expends energy levels quickly so it takes a well balanced regimen of training and practice to achieve results we can readily see in the old Bruce Lee demonstrations of the sixties, before he passed away. 

Also, take notice in his demonstrations how he makes efficient use of his whole body and especially his “hara” or midsection. 

https://youtu.be/v8wL3AA4BP0

This can be tough, coordination of the hara to all that you door be it hand or feet is about timing, balance and dynamic tension/positive relaxation. The more you are able to bring forth movement from the hara and just let positive calmness/relaxation work in mushin the faster you will get while coordinating that with transferring power and energy to the intended target is a daunting strategy! Ergo, “Be like water, my padawan!”