What are Fast Twitch Muscles and Why are They so Important?

Most of us don’t have kinesiology degrees, so it's easy to think that a muscle is just a muscle. However, the muscle fiber type is the key differentiator. Fast-twitch muscles

contract quickly and are responsible for speed and explosive movements, while slow-twitch fibers are used for endurance and everyday activities.

Fast-Twitch Muscle Fibers

Fast-twitch muscle fibers are essential for explosive movements and high-intensity activities. They are divided into two main types:

• Type IIa (Intermediate fast-twitch): These fibers can sustain longer bursts of activity and have a higher resistance to fatigue than Type IIb fibers.

• Type IIb (Pure fast-twitch): These fibers generate the most power and are recruited for short, explosive activities.

As you age, you lose fast-twitch muscle rapidly, at a rate of 3-5% per decade. This decline is evident in world records for activities involving fast-twitch muscles, such as the 100-meter dash and deadlift.

Aging and Fast-Twitch Fibers

As we age, the decline in muscle mass and function (sarcopenia) disproportionately affects fast-twitch fibers. Both sprinting and lifting heavy weights become more challenging, but the extent and nature of the decline differ:

• Sprinting: The loss of fast-twitch fibers severely impacts speed and agility, resulting in more significant declines in sprint times.

• Strength Training: While there is a decline in maximal strength, strength training and activities like deadlifting tend to preserve muscle mass and function better than purely speed-based activities. This results in a relatively slower decline in performance compared to sprinting.

What can you do?

To preserve fast-twitch fibers, focus on controlled strength training rather than just endurance activities. Fast-twitch muscle fibers help prevent falls and adjust movements quickly. They send rapid signals to the brain, which is crucial for maintaining balance and agility. This effort can prevent age-related issues like stiffness, joint pain, and slowing speed.

Even if you run, play tennis, or hike, you might still be missing the benefits of training fast-twitch muscles.

Here are some fast twitch muscle exercises you can work into your routine:

• Medicine Ball Slams: This exercise involves lifting a medicine ball overhead and forcefully slamming it down to the ground. It's great for developing explosive power and engaging fast-twitch muscle fibers in the upper body and core.

• Split Squat Jump: Begin in a lunge position, then explosively jump and switch legs in mid-air, landing in the opposite lunge position. This targets fast-twitch fibers in the legs and helps improve lower body power and coordination.

• Box Jump: Stand in front of a sturdy box or platform, then jump onto it with both feet, landing softly. This exercise builds explosive power in the legs and enhances overall lower body strength and agility.

To see more agility exercises that help with fast-twitch muscles, please download our free exercise template here. https://www.futurefityou.com/