Go Ahead and Jump: Using plyometric training to improve running performanceAugust 9th, 2010
Plyometric training combines strength, speed and neuromuscular efficiency to produce power. Marching drills and jumping exercises make up the majority of this type of training, during which a muscle is loaded and contracted rapidly in a sequence known as the stretch-shortening cycle. This mechanism, along with the stretch reflex, forms the basis of all plyometric activities. Plyometric training can improve running economy and performance.
[See this article in this month's Canadian Running Magazine for excellent pictures demonstrating these moves]
Plyometric training focuses on increasing power output by enhancing the stretch-shortening cycle. It is thought that plyometrics result in the stiffening of the lower-limb joints during ground contact, reducing the delay between eccentric and concentric muscle contractions. This means that during each foot contact, the stretch-shortening cycle would be more efficient, leading to a more economical running style. Plyometrics also boost brain-muscle communication with minimal muscle bulking - good news for runners, who need to be able to produce force quickly, while attaining a high strength-to-bodyweight ratio.
The science
The stretch-shortening cycle is made up of three phases: the eccentric breaking phase, the amortization phase and the concentric acceleration phase. During the stretch (eccentric contraction) of a muscle, the muscle and tendon act like a spring and store elastic energy, as when landing from a jump. The amortization phase, also known as the pause phase, must be brief; otherwise the stored energy will be lost as heat. The shortening (concentric contraction) phase can use the stored energy to produce more power, as in performing another jump immediately after landing from a previous jump.
The stretch reflex is a neurophysiological mechanism that’s also responsible for increasing power output. A simple example of the stretch reflex is the knee-jerk response when your patellar tendon is tapped with a rubber mallet. The tendon is stretched when struck by the mallet, resulting in an involuntary contraction of the quadriceps muscle. The stretch reflex is proportional to the rate at which the muscle is stretched. Plyometric training improves the strength of the reflex response, resulting in a more forceful contraction.
Exercise progression - The four levels
There are four levels to progress through when learning plyometric exercises.
Level 1: Develops eccentric strength to prepare the body for plyometric exercises
Sample exercise:
Rear-foot elevated split squat
Stand with your rear foot placed on an exercise bench. Your front foot should be a lunge length in front of the bench. Drive your rear knee straight into the ground as you descend, keeping the front knee above the ankle. Once your front thigh reaches parallel, drive your front foot into the ground to return you to the starting position. Perform 3 sets of 10 repetitions. When stability and coordination have improved, perform the exercise with a controlled fast descent.
Level 2: Develops proper landing mechanics, posture and reactive neuromuscular efficiency
Sample exercise:
Squat jump with stabilization
Stand with your feet shoulder-width apart. Perform a squat by pulling your hips back as if you were trying to sit on a little stool behind your feet to load your hamstrings and gluteals. Allow your body to lean slightly forward from the hips. Bring your arms back as you preload for the jump. Drive your feet into the ground, swing your arms forward and up while you explode into the air. Land softly in the starting position with your shoulders over your knees. Hold for 3 seconds. Stand up. That is one repetition. Perform 3 sets of 5 repetitions.
Level 3: Develops dynamic joint stability, eccentric strength, a faster rate of force production and neuromuscular efficiency. Progress from the squat jump with stabilization to continuous squat jumps
Sample exercises:
Continuous squat jumps
Using the jumping and landing techniques described in Level 2, upon landing from a squat jump, immediately explode up into another squat jump. Perform 3 sets of 5 continuous jumps. When your technique and strength improve with the squat jumps, progress to the single leg jump with stabilization.
Single leg jump with stabilization
While standing on one leg, squat down with proper mechanics and explode into a jump. Land softly with proper technique and stabilize the position for 3 seconds. Perform 3 sets of 5 jumps per side.
Level 4: Now we’ve reached the level of true plyometric exercises. The focus at this stage is to improve the rate of force production and reactive strength and to decrease the amortization phase
Sample exercises:
Double/Single leg hurdle jumps
Set up 6-8 hurdles equally spaced at about mid-shin height. The height of the hurdle will be determined by your strength and training experience. Hop through the hurdles, focusing on light, soft, quick landings. Pretend the ground is hot to make your ground contacts quicker. Walk back after hopping through the hurdles. Hop over the hurdles for a total of 5 sets.
Single-arm alternating leg bounding
Bounding drills consist of exaggerated running movements with greater horizontal velocity. To perform this drill, jog at a comfortable pace and start on the left foot. When landing with the left foot, propel the body forward while driving the right leg forward by flexing the hip and knee to 90 degrees. Reach forward with the left arm and try to cover as much distance as you can. Land on the right leg and immediately repeat the sequence on that side. Perform this drill for a distance of 30-45 metres for a total of 3-5 sets.
Plyo Pointers:
1. Before starting a plyometric training session, do a good warmup. Jog for 10-20 minutes and perform skipping and dynamic warmup drills such as walking lunges and leg swings.
2. Be cautious about the intensity. The intensity of the session is measured by number of foot contacts, speed of the drill, distance covered, height of the drill and your body weight. For example, hops are less intense than bounding drills. Progress safely.
3. Runners can benefit from 1-2 plyometric sessions per week.
4. Plyometric drills are considered power training. Don’t focus on trying to increase cardiovascular fitness with these types of sessions. Take 2-3 minutes of recovery between sets and 48-72 hours of rest between sessions.
5. Beginners should have roughly 80-100 foot contacts per workout.
6. Follow the principle of progressive overload. Don’t try advanced plyometric drills without reaching that level during your skill development.
7. Perform the exercises on a forgiving surface, such as a grass field.
8. Wear supportive footwear.
9. Perform plyometric sessions fresh, not right after a hard run.
10. Adolescents and older runners should avoid high-intensity plyometric drills.
Jon-Erik Kawamoto is a Strength and Conditioning Coach in Burnaby, B.C. (www.JKConditioning.com).
Source: Canadian Running Magazine: http://runningmagazine.ca/2010/06/sections/health-nutrition/body-work/go-ahead-and-jump-using-plyometric-training-to-improve-running-performance/