Plyometrics refer to the “type of muscular activity produced when an impulsive eccentric movement terminates suddenly, eliciting a powerful stretch reflex and causing a maximal rebound concentric muscle contraction.” (Siff, 2002) It is basically the rapid shock loading of a muscle (think springs) followed by an immediate elastic energy output.
A classic example of a plyometric exercise is the In-depth jump: Jump off a chair or box (20 to 80 cm) onto the ground and immediately and explosively spring back up (jump) after hitting the floor. ***This can be a very dangerous exercise if not done properly, read more below.
Myth: Standing/Static jumps are not plyometrics – they do not involve a rapid shock of muscle loading with a short landing phase.
All of your muscles are toned all the time unless you are dead. Let’s hope that is not the case. Skeletal muscles maintain a modicum of tension all day everyday in order to deal with various types of movement. You cannot go to the gym to “tone your muscles” as this is already their natural state. It drives me crazy when I hear trainers say “let’s tone your arms today!” Muscle tone is created by the electrical activity coursing through your body. It is a form of readiness which allows you to produce massive amounts of body tension at a moments notice. This tension enables the human body to express lots of energy to move things in space. Your muscles, tendons and fascia can act as springs, essentially storing and releasing this energy. All voluntary movement is governed by this spring like action of kinetic and potential energy. You can learn to potentiate this energy with plyometric training.
But don’t jump yet…here is a quick physics lesson:
When you step on the ground the speed of the movement and mass of your body elongates soft tissue throughout your body in the foot, leg, hips, core and back to produce kinetic energy. This energy is like the force pulling a spring into a stretched position (or pulling a rubber band apart). The harder and faster you pull on the spring the greater the recoil. Kinetic energy is simply the energy something has because it is moving. The deceleration of your foot on the ground primes your body with potential energy. The body spring reacts just as forcefully and begins to pull up (spring back). The pulling up action will release the potential energy and convert it into elastic energy. Think rubber band snapping back into place. This process then repeats.
Summary: Kinetic energy is converted into potential energy which is released as elastic energy.
When performed properly plyometrics are a powerful tool, helping athletes increase their speed and jumping power. Sadly, too many individuals do not follow a well planned periodization model and jump right into plyos without the proper know-how. It is always good to get a second pair of eyes (coach or competent friend) and even a slow-motion camera to record and evaluate your form. It is very easy to injure oneself while doing plyometric training….big benefits but big risks.
Rules of Lower Body Plyometric Training (PT):
- Do them barefoot: this will ensure the elastic component of your arch and lower leg will be completely utilized and will increase your preactivation stretch reflex response.
- Minimize ground contact time: .2 seconds or less. If contact time is longer the elastic energy and myotatic stretch reflex will have dissipated. Stay on the ground too long and most of that kinetic energy vanishes.
- Warm up prior to PT training including full active range of motion movements.
- Do not weight lift/strength train prior to PT. This will likely lead to muscle fatigue and faulty form.
- Do not static stretch prior to PT. This will decrease the intensity of neuromuscular contractions.
- Make sure you have good landing mechanics. Maintain proper alignment in ankles, knees and hips.
- Do not land on soft surfaces like padded mats or Airex pads. The chance of twisting an ankle is high and the soft landing will decrease your stretch reflex.
- Practice micro-progression rules. Slowly integrate this training into your program and allow adequate rest between bouts (48 hours) and in between reps.
- Always start with a low height and increase incrementally over time when doing in-depth jumps.
Here are my two favorite plyometric exercises to increase speed and help with running mechanics. I would not recommend performing the 1st movement more than 3x per week. Typically 2-3 sets of 4-6 reps will suffice. The second exercise can be done for 30-60 seconds at a time for 2-3 sets. As a beginner less is more. Generally 1-3 minutes between sets and 3-5 minutes between exercises is sufficient recovery within a single training session.
1. In-Depth Jump – Stand on a platform 30 cm (up to 80 cm high) and step off, do not jump off, the end. Let the balls of your feet hit the ground first; absorb the impact by bending your knees and hips; and immediately explode back up into the air with maximal force; as you propel upwards pump your arms toward the sky.
2. Single Leg Hop with Bar: Put a piece of rope or tape on the ground and hop as close to this as possible; with an upright posture hold a 10-12lb barbell overhead with straight arms; with one leg hop up and down at an optimal running cadence of 180 beats per minute; land on your forefoot and let your heel kiss the ground before you op right back up. Go for 30-seconds to a minute.
High intensity is key for plyometric training – 95-100% effort. Quality, not quantity, is the cornerstone of these exercises. However, there must be a balanced relationship between stress and recovery. Insufficient recovery and bad form are the most common cause of injury in plyos. Do these exercises on a regular basis and within weeks you will see dramatic improvements in your runs.