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Power Training Principles: Form and Execution
This is an excerpt from High-Powered Plyometrics-3rd Edition by James C. Radcliffe.
Gearing Up for Power
Whether you are a participant or a coach, you should keep power training principles in mind as you evaluate your teaching, learning, and testing. Basic progressions and assessment procedures provide good training and lead to more complex training methodologies.
Form and Execution
Proper form and execution are best evaluated by assessing the posture, balance, stability, and mobility of each exercise repetition. Is the exercise performed with upright postural control? Is the movement balanced on the instep of the support foot? Is the movement stabilized throughout all the joints involved? And is the movement performed with the optimal range of motion (mobility)?
This section provides guidelines for executing most of the plyometric jumping, bounding, and hopping exercises. Following these guidelines will result in optimal skill performance. Applying these guidelines swiftly during support-leg coupling, the critical point at which the eccentric part of landing switches to the concentric part of takeoff, is known as transfer of force (Jacoby and Fraley 1995). It becomes the center point from which we can evaluate effective load handling, pre-tension, and postural control training with and for optimal performance.
Toe-Up Guideline
The toe-up guideline involves using locked ankles in slight dorsiflexion, with full midfoot-to-forefoot ground contact upon landing (see figure 3.1). The spring-loading effect of the foot and ankle keeps the foot from pointing or hanging in a toes-downward position. Keeping the toes upward and the ankle locked in a neutral loaded position can reduce the effect of slack (see chapter 1) and help pre-tense the body for better-activated landings. The field of podiatry has dubbed this aid in stiffness the windlass effect.
Toe flexion is imperative for both shock absorption and propulsion during the gait cycle, and free movement of the toes is essential for an effective windlass effect in the foot. The absence of the windlass mechanism has been proven to play a role in many foot and lower limb injuries. The beauty of being barefoot in early training and learning progressions is that when toes are exposed, proper foot and ankle positioning occurs naturally.
Knee-Up Guideline
The knee-up guideline promotes maximal knee drive and hip extension, or projection. The sweeping or driving of the swing knee forward and thus upward maximizes the distance between this knee and the opposing and extended stance knee (see figure 3.2). When evaluating acceleration mechanics and effective stride length in almost all directions, we often look for the space between the knees, not between the feet.
Hip-Up Guideline
When the knees perform proper upward lift mechanics, the hips can be projected more effectively. Using good postural control and keeping the hips lifted upward and forward reduces slack in the landing system and enhances ground negotiation (see figure 3.3). Considering the body as a stick figure, the more bent segments that exist during ground contact, the more time the person spends on the ground during that contact. When the hips are lifted upward, forcing a straighter posture in relation to ground contact, the contact will be more efficient and forceful.
Heel-Up Guideline
The heel-up guideline projects the hips further and improves body flight by reducing the arc and rate of the swing leg (see figure 3.4). The most common cause of improper running mechanics is that the heel begins to go backward and then upward when the foot leaves the ground instead of upward and forward immediately after takeoff. The heel-up guideline involves initiating tilting and flexing from the hip rather than flexing at the knee. The good news is that when the toes are flexed up and the knee is driven upward and forward, the heel is more likely to move in the proper direction, placing itself directly under the belly of the upper thigh in preparation for the next ground contact.
Thumbs-Up Guideline
The thumbs-up, or blocking, guideline is used for upper-body posture and continued force expression. According to Sir Isaac Newton, there is an equal and opposite reaction for every action. When the knees are driven upward in jumping, bounding, and hopping exercises, the equal and opposite reaction is that the shoulders drop forward to meet them. The act of forcefully punching the thumbs upward (as if to poke your eyes out, yet stopping just before reaching the eyes), also known as blocking, keeps the shoulders upright and the torso in proper takeoff and landing posture. From an elbows-back preparation, this action synchronizes the summation of force upward, preparing the person for the next takeoff (see figure 3.5). Allowing the thumbs (or hands) to circle up and back over the head slows the entire movement and elicits a loss of force.
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