Want to improve your vertical jump? How about your speed and agility? Add plyometric drills to your strength and conditioning program to quickly increase your explosive power.

How Plyometrics Work

Lifting heavy weights won’t help you much on the field if you can’t lift them fast. A 400-pound Squat won’t help you jump any higher than a teammate who can only squat 200 pounds. You’ll run faster and jump higher if you’re able to put more force into the ground quicker. (Check out Increase your power with sand plyos.)
Plyometric exercises enable muscles to reach maximum force in the shortest possible time, using something called the stretch-shortening cycle (SSC). The exercises increase the power of subsequent movements by using both the natural elastic components of muscle and tendon, and the stretch reflex.1
The exercises must be quick and powerful movements that follow the pattern below:

• Eccentric phase: preloads (stretches) the muscle, as when squatting before a jump
• Amortization (transition) phase: pause between the eccentric and concentric phases, as when transitioning from squat to jump
• Concentric phase: muscle contracts to produce explosive movement, as when jumping

Types of Plyos

Lower-body plyometrics are appropriate for virtually any athlete in any sport. These drills usually involve hopping and jumping, and include the following:

• Jumps in Place: Jumping Jacks, Jumping Rope, Squat Jumps and Tuck Jumps
• Jumps Over Barriers: Hurdles, cones, etc.
• Multiple Hops and Jumps: Rapidly repeating jumps or hops
• Bounds: Bounding, Lateral Bounding, Broad Jumps
• Box Drills: Box Jumps, Lateral Box Jumps, Single-Leg Box Jumps
• Depth Jumps: Stepping off box and jumping immediately for distance or height (advanced)

Plyometric drills for the upper body are not performed as often as those for the lower body, but they should not be ignored. The upper body needs to be explosive for throwing, swinging and pushing.

• Push-Ups: Plyo Push-Ups, Clap Push-Up, Lateral Plyo Push-Ups
• Med Ball Drills: Explosive Med Ball Throws, Med Ball Partner Tosses

Plyometric Workout Design

Plyo exercises place great stress on muscles, tendons and joints; and too much plyo work can cause injury or inhibit performance. Therefore, it’s important to carefully plan your plyo workouts and listen to your body.
Plyometric training sessions can be performed one to three times per week, depending on your sport and the time of year. Base the workouts on the following guidelines:

• Volume: Beginners, 50-60 reps total / Advanced, 100-120 reps total
• Recovery: 5-10 seconds for every second of work to allow for full recovery
• Warm-Up: Perform a full dynamic warm-up before every plyo workout to prevent injury

Safety Considerations

• Perform plyos only after building an adequate base of strength, speed, and balance
• Start with simple plyo exercises and progress to more advanced versions
• The landing surface must be flat and shock-absorbant; grass fields, rubber mats and padded plyo boxes are all good choices
• Wear supportive, non-slip footwear
• Always perform plyos in the presence of a qualified strength coach

Source
1 Jared W. Coburn and Moh H. Malek, Eds., NSCA’s Essentials of Personal Training. 2nd. Ed., 2011.