You know that feeling when you’re at the starting line, heart pounding, muscles tensed, ready to explode into action? And how about that feeling when you swing a heavy kettlebell or lift a heavy weight? That’s the power of your fast-twitch muscle fibers kicking into high gear. But how much do you know about your “fast-twitchers?” Let’s take a closer look at these fibers and how to train them.
Let’s start with the basics. Fast twitch muscle fibers, also known as Type Il fibers, are responsible for generating quick, powerful bursts of movement. When you see an athlete sprinting or sprinting yourself, or when you do intense strength training, your fast twitch muscles rise to the occasion. These are the fibers that give you explosive force. In contrast, slow-twitch muscle fibers (Type I fibers) are designed more for endurance rather than speed and power.
But fast twitch fibers aren’t just for elite athletes – you use them for movements you do every day. When you pick up a bag of heavy groceries or chase your dog around the yard, your fast-twitch muscle fibers do much of the work.
Characteristics of Your Fast-Twitch Muscle Fibers
Fortunately, fast twitch fibers are highly trainable, which means that with the right approach, you can increase their size and strength, so they do more work for you. Here’s an interesting fact. Elite weightlifters have more fast-twitch muscle fibers than the average person. You might think the higher ratio of fast-twitch fibers to slow-twitch fibers is genetic but that’s not the full story. Athletes who competed longer had more fast-twitch fibers, suggesting you can increase the number through training.
But before looking at how to train them, let’s dig deeper into their characteristics.
Contraction Speed
Fast twitch muscle fibers contract quickly, giving you the ability to generate quick bursts of power for sprinting, jumping, or lifting a weight explosively. They can do this because they have more myosin ATPase, an enzyme that breaks down ATP, than slow-twitch fibers. This means they have super-fast shortening velocities.
Force Production
When you compare fast twitch and slow twitch fibers, the former has a higher density of myofibrils and a larger cross-sectional area, so they can generate more force than slow twitch fibers can. This makes them ideal for enhancing strength and power.
Fatigue Resistance
Unlike slow-twitch fibers that you use during endurance exercise, fast-twitch muscle fibers fatigue quickly. This makes these fibers perfect for intense activities that are short in duration, but you can’t depend on them to contract for long periods of time. When they fatigue, you’re dependent on your slow-twitch fibers and must slow down.
Training Fast Twitch Muscle Fibers
Why do you want to train fast-twitch muscle fibers? Training your fast-twitch fibers is key to preserving muscle power, explosiveness, and mass. You lose fast-twitch muscle fibers faster with age than you do slow-twitch ones and such loss affects your functional fitness. So, the reasons you want to train them is to:
- Preserve and increase power and explosiveness.
- Preserve and build muscle mass.
- Maintain functional fitness.
- Improve athletic performance.
Now let’s look at strategies for working your fast twitch muscles:
High-Intensity Interval Training (HIIT)
With HIIT training, you alternate periods of intense effort with periods of recovery or lower-intensity exercise. This is one of the most effective ways to train fast twitch muscle fibers and improve their ability to produce power.
Plyometrics
Plyometric exercises, such as jump squats, box jumps, and clapping push-ups, involve explosive movements that engage fast twitch fibers. When you do these exercises, you strengthen your fast twitch fibers and boost power, speed, and reactive strength. Plyometrics are powerful performance enhancers for your athletic goals.
Resistance Training with Heavy Weights
Lifting heavy weights with low to moderate repetitions recruits and overloads fast twitch muscle. Therefore, your increase muscle size and strength while training your fast-twitch fibers. .
Explosive movements
Other ways to train your fast twitch fibers are by doing sprints, medicine ball throws, kettlebell swings, and Olympic lifts. When you do these activities, you generate rapid force that enhances your fast twitch muscle fibers, so you can generate more power.
Nutrition and Recovery
You need proper nutrition and recovery strategies to develop fast twitch muscle fibers. Imagine your muscles as a finely tuned engine, with fast-twitch fibers acting as the high-performance pistons that generate explosive power. Just like a race car requires premium fuel and meticulous maintenance, your fast-twitch fibers demand a strategic approach to nutrition and recovery. Neglect them, and you risk stalling your progress, leaving your potential for speed and strength idling in the pits.
Replenishing glycogen stores is crucial for maintaining your explosive power and preventing the dreaded “bonk” or “hitting the wall.” Incorporate complex carbohydrates like whole grains, fruits, and vegetables into your post-workout meals and snacks to refill your body’s fuel tank.
And don’t forget about rest and recovery. Even the most finely tuned engines need regular maintenance and downtime to perform at their best. Your fast-twitch fibers are no exception. Intense training sessions can leave these powerful fibers feeling like they’ve just completed a grueling race, so it’s essential to allow for adequate rest and recovery between workouts. During this pit stop, your body repairs and rebuilds the muscle fibers, ensuring they’re primed and ready for your next high-intensity performance.
Keep Your Training Balanced
While fast twitch training is important, strive for balance.
By structuring your strength training program around exercises incorporating both fast and slow-twitch fibers, you’ll not only cultivate explosive power but also build the endurance and stability you need to safely perform movements that require strength, power, and explosiveness. Plus, don’t ignore the benefits of being flexible, agile, and coordinated. You need a comprehensive approach to training that addresses all facets of fitness.
But also keep your goals in mind. Tailor your training regimen to the specific demands of your sport or activity, carefully balancing exercises, intensities, and periodization strategies to optimize both fast and slow-twitch fiber adaptations. Since you lose fast twitch muscle fibers faster with age, training these fibers should become a priority as the years go by. So, keep it balanced, but also understand how important it is not to ignore fast twitch training.
References:
- “Fast Twitch Muscles: About, Benefits, Exercises, Vs. Slow Twitch.” 14 Jan. 2020, https://www.healthline.com/health/fast-twitch-muscles.
- “Fast-Twitch Vs. Slow-Twitch Muscle Fiber Types + Training Tips.” https://blog.nasm.org/fitness/fast-twitch-vs-slow-twitch.
- Serrano N, Colenso-Semple LM, Lazauskus KK, Siu JW, Bagley JR, Lockie RG, Costa PB, Galpin AJ. Extraordinary fast-twitch fiber abundance in elite weightlifters. PLoS One. 2019 Mar 27;14(3):e0207975. doi: 10.1371/journal.pone.0207975. PMID: 30917128; PMCID: PMC6436686.
- Hall ECR, Lysenko EA, Semenova EA, Borisov OV, Andryushchenko ON, Andryushchenko LB, Vepkhvadze TF, Lednev EM, Zmijewski P, Popov DV, Generozov EV, Ahmetov II. Prediction of muscle fiber composition using multiple repetition testing. Biol Sport. 2021 Jun;38(2):277-283. doi: 10.5114/biolsport.2021.99705. Epub 2020 Oct 22. PMID: 34079173; PMCID: PMC8139349.
- “Extraordinary fast-twitch fiber abundance in elite weightlifters.” 27 Mar. 2019, https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0207975.
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