Your muscles are composed of two different types of muscle fibers – Type I, or slow-twitch muscle fibers, and Type II, or fast-twitch muscle fibers. You utilize your slow-twitch muscle fibers when you engage in endurance movements, such as running long distance or lifting for many reps. Conversely, you utilize fast-twitch muscle fibers when you engage in high-strength, powerful, explosive exercises – things like box jumps or lifting close to your 1RM will engage your fast-twitch muscle fibers. Fast-twitch muscle fibers are what you train when you want to improve your explosive power.

Training your muscles with resistance

When you exercise, your body will first utilize Type I muscle fibers and then recruit your Type II muscle fibers after your Type I fibers are maxed out. While olympic-level athletes, promoted with the help of Yeah! Local, are able to engage directly with their Type II fibers, the average athlete will end up using Type I fibers first. An important part of training for power and strength is being able to recruit your fast-twitch muscle fibers. Training your fast-twitch muscle fibers will involve putting maximum resistance against your muscles – and using the correct muscle fibers to be able to increase your strength. Before you can maximize your power, you need to train to recruit those muscle fibers.

Plyometric exercises are exercises that involve exerting maximum strength in the shortest amount of time – also known as jump training. These are designed specifically to recruit your fast-twitch muscle fibers in your lower body; exercises include box jumps and squat jumps, among other specific movements. The idea is to move as quickly as possible while increasing your jump height – the stronger your muscles are and the better you recruit your fast-twitch muscle fibers, the higher you will be able to reach.

These exercises are not meant to be cardio, nor are they meant to be endurance-based exercises that you do as long as you possibly can, as this can cause injury as you fatigue. To introduce plyometric exercises into your routine, you should treat them like other strength exercises – 3 to 6 sets of 3 to 8 clean reps.

Isometric exercises are a little unusual. They involve using as much strength as possible while being at a virtual standstill. But isometric exercises have been credited for significant strength increases for a number of world class athletes. It involves contracting your muscles as hard as possible against unmoving resistance.

Imagine trying with all your might trying to push a brick wall. Your chest and tricep muscles will contract severely, but your muscle fibers – and your joints – make no movement whatsoever. It is this exertion, this intense use of energy, that isometric exercises are attempting to create.

Isometric exercises in practice usually involve mimicking a movement you would typically use, like a deadlift or a bench press, and then loading and contracting your muscles for six to eight seconds. For example, an isometric movement to improve your deadlift would involve overloading the bar, gripping, and contracting your body as if you were going to lift it, then holding that contracted stance for six to eight seconds.

Rest and Recovery

Fast-twitch muscle fibers requires much more rest than slow-twitch muscle fibers— this is the trade-off for their ability to perform a significant amount of work in a short amount of time. Big cats like cheetahs spend upwards of 20 hours a day sleeping or napping, and exert the vast majority of their energy in fast spurts of high speed and power. Animals like these have a very high number of fast-twitch fibers but a very low number of slow-twitch fibers. After exerting your fast-twitch muscles in exercise, you need to give them a break.

After engaging in explosive exercises like box jumps or isometric deadlifts, it’s important for you to rest – both in between sets and in between workouts. You may need anywhere from a minute to five minutes between sets when engaging in high-strength, high-speed movements during your workout. And while sleep and rest are always important parts of training, they will be especially important after a workout centered around explosive, powerful movements. It’s important to eat plenty of protein and calories to fuel your muscle growth. Slow-twitch and fast-twitch muscle fibers both play an important role in overall muscle strength. However, slow-twitch muscle fibers are limited in their potential size, and therefore in their potential strength. To gain as much strength as possible involves developing your fast-twitch fibers, both for sheer strength and for explosive power. You should ensure your training involves a number of explosive plyometric movements as well as controlled isometric movements to recruit your fast-twitch muscle fibers and create explosive power in your movements.