The Best Way to Train Slow- and Fast-Twitch Muscles

You’ve probably heard of your slow-twitch and fast-twitch muscle fibers. These muscle fibers are the two different types of muscles within your body that control your athletic ability regardless of your sport.

Slow-twitch muscle fibers (called “Type I”) don’t generate a ton of force rapidly; instead they generate sustained force for a long period of time. Slow-twitch muscle fibers are important for endurance sports like marathon running because they have a lot of capillaries to deliver blood to the muscles, which helps provide more oxygen and clear waste.

Fast-twitch muscle fibers (called “Type II”) generate far more immediate power and strength. They fatigue a lot faster, however, and need much more time for rest and recovery.

While both types are better for different purposes, almost every sport requires a combination. Focusing on just one makes you imbalanced. That’s because sports like football, soccer, basketball and even swimming have a strength/power and endurance component.

Traditional strength exercises like squats and bench presses do wonders for your fast-twitch muscle fibers, especially if you keep your reps at a lower range like 3–5.

Once you get to a solid level of strength, add super-fast, power exercises like snatches, jerks and cleans, where you have to move a heavy weight as fast as you possibly can. (For these, also keep your reps low.)

Other great explosive moves that isolate your fast-twitch muscle fibers are lighter exercises like kettlebell swings, slams with medicine balls or plyometrics. Here, you can use slightly more reps like 5–8. Avoid doing more because you’ll start exhausting your Type II muscles and shift the work onto your slower ones (which is exactly what you’re trying to avoid).

Because fast-twitch muscle fibers exhaust quicker, do these explosive exercises early in your workout, preferably after your warmup and before your traditional strength exercises.

One of the best ways to increase your slow-twitch muscle fibers is with a method called “tempo lifting.”

Instead of focusing on how many reps you do, focus on using a slower tempo with your strength exercises for time — for example: 3 seconds to lift and 3 seconds to lower. Keep in mind, because the movement is slower, you might have to use less weight. Also, using shorter rest periods can further train and improve your muscular endurance.

With tempo lifting, focus on perfect technique and use exercises that don’t require complicated moves (because your form might worsen with fatigue).

Doing this kind of tempo lifting makes your body more fatigue-resistant, which provides a solid foundation before you transition to your fast-twitch training.

Goblet Squats

2 sets x 60 seconds each (3 seconds up, 3 seconds down, no pause between reps)
Rest: 60 seconds between sets

Pushups

2 sets x 60 seconds each (3 seconds up, 3 seconds down, no pause between reps)
Rest: 60 seconds between sets

Inverted Row

2 sets x 60 seconds each (3 seconds up, 3 seconds down, no pause between reps)
Rest: 60 seconds between sets