Plyometrics teach your muscles to exert maximum force in minimum time. If you think this sounds like the benefits of strength training, you're right. When it comes right down to it, both styles of exercise create stronger, faster and more powerful athletes.
But the similarities only go so far. Plyometrics and weightlifting develop different aspects of your muscles, each contributing to the amount of power your muscles can produce. When both methods are included in a training program, it's possible to maximize your performance gains.
To understand the difference between the two types of training, you need to understand the stretch-shortening cycle. The SSC is a function of your muscles that occurs when you change directions in a hurry, such as when landing from a jump and jumping up again, or quickly making a cut to change directions. It's a three-step process in which your muscles slow down your body's momentum, hold on to the energy for a tiny fraction of a second, and convert that energy into forceful movement.
Exercise physiologists call these three phases "eccentric," "amortization" and "concentric," but we'll call them lengthen, load and fire.
Of the three, it's the middle one—load—that makes a plyometric a plyometric.
Here's specifically what goes on in your muscles during each phase:
Phase 1: Lengthen
During the lengthening phase, your muscles do exactly that—they get longer to slow your body down.
They do this whenever you need to absorb impact, such as when your feet hit the ground after a jump. Your muscles, such as your glutes, quads and hamstrings, stretch and create tension until your body is no longer moving. Just like a stretched rubber band, your muscles now contain elastic energy. On to Phase 2.
Phase 2: Load
Load is the shortest—but most important—of the three phases. How short? Ideally, you execute the load in 15 to 20 milliseconds.
If it takes longer than 25 milliseconds—1/40th of a second—you lose the stored energy. It dissipates from your body as heat. But if you move through this phase quickly, your body takes that energy and channels it into your next movement. To the untrained eye, it happens so fast, it looks like nothing happened. But what really occurred is that your body loaded up on energy, which you then unleash in Phase 3.
Phase 3: Fire
In this final phase, your muscles contract quickly and forcefully to produce a powerful movement, like a jump.
Can your muscles do this without going through the stretch-shortening cycle? Yes. But the SSC provides them with an extra boost—the elastic energy you create in Phase 1 and store in Phase 2.
To see what a difference this makes, tap your index finger against a table as hard as you can. Notice the sound. Now use your opposite hand to pull that same finger back and and let it snap against the table. The second tap is a lot louder because the elastic energy created when you pulled your finger back allowed you to generate greater downward force.
Plyometric exercises are meant to be done with max force in as little time as possible. This allows you to spend less time on the ground between jumps. Your transition speed is faster, and less elastic energy is wasted as heat, making for more powerful movements that specifically develop the SSC.
Strength exercises do not train the time element of Phase 2—even if performed explosively. They're simply too slow to train the SSC, because they lack a rebound, or quick transition, between the phases. However, strength training does create stronger muscles that are capable of producing more force. Plyometrics are the fastest way to turn the strength you build in the weight room into speed and explosiveness on the field.
So when you're building your training program, consider adding plyometrics to your routines. To get the most out of your time spent in the weight room, ideally you should spend about 10 minutes performing plyometrics after your dynamic warm-up and before strength exercises.
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