Plyometrics are probably the most interesting part of athletes workouts. Or at least, the flashiest. It’s alluring to think that trying an advanced secret variation of an explosive jump that you saw on a youtube video of an MMA fighter (or professional dunker, or any other high level athlete) will morph you from Clark Kent into Superman.
Rate of force development (RFD) can be broken down into two stages. There is an early stage rate of force development and a late stage rate of force development. Early stage RFD is typically measured from 0-100 ms while late stage RFD is anything after.
Importance of Early Stage RFD
Sporting movements are often required to be fast, reactive movements that occur over a small amplitude. For example a large countermovement jump can take between 500-1000ms, while a squat jump with no countermovement may take around 300 to 430ms (1). In sport, movement amplitude is going to be much more similar to that of a squat jump (zero to minimal countermovement) than to that of a large CMJ. At the same time, sprinting ground contact times can last as short as 100ms. With this in mind, it is easy to see how early RFD may play an important role in sporting movement, especially those covering a small amplitude over a short period of time (ranging from 100-430ms).
Frans Bosch has popularized the concept of muscle slack (Van Hooren has publications on it). It is hinges on early stage rate of force development and the speed at which the muscle, tendon, and series elastic element can go from “slack” to “tense”. When a muscle is not activated, it is relaxed and there is slack in the muscle, tendon, and series elastic element as it hangs from its origin and insertion. Bosch uses the analogy of a rope to help describe how muscle slack works. You are holding one end of the rope and the other end is tied to a car, you are the origin and the car is the insertion. Before you can pull the car with the rope, the rope first has to become tense. This is the point where the rope goes from lying slack on the ground, to now in a straight line from your hands to the car. This is synonymous with the process of the muscle fibers aligning from the origin and insertion. The second part of the slack is that the rope now needs to become tense enough so that force can be applied to the truck. At this point, the rope goes from being in a straight line from your hand to the car, to now taut, from you producing a force on the rope. This is synonymous with the muscle co-contracting to produce enough force on the tendon so the muscle can become tense. Muscle slack uptake occurs during start of where the contractile element receives the chemical signal to align all the way to the point where both the musculotendon unit and the series elastic element are tense.
This week, we explored arguably one of the most significant areas of the body when it comes to contributing to pathology.
The thoracic spine is 12 segments (vertebrae) that are the bridge between the cervical spine and lumbar spine. On top of that, the ribs/ribcage articulate with the thoracic spine, and that scapula articulates with the ribcage…this creates a pivotal relationship with the thoracic spine and the shoulders.
Being “elastic” or “reactive” refers to being able to have a good ability to quickly develop force and transfer one movement’s energy into another. The reactive strength index (RSI) is one of the most commonly used field tests for assessing these qualities. The RSI is the jump height of the movement divided by ground contact time. In other words, the higher you jump and faster you get off the ground the better your RSI will be.
The drop-catch method was detailed in one of my previous posts (click here). It is a method that utilizes higher velocity loading schemes and less weight on the barbell to provide an overload stimulus to the athlete. It is centered around the idea of having to rapidly absorb a high(er) eccentric velocity loads over a shorter period of time and over a smaller range of motion.
The Banded Squat Drop
The banded squat drop can be used in the squat drop progression. Obviously, the banded version would come after the body weight and barbell versions, but the methods of application are the same.
“One which uses strength training to raise force production of the muscles as far as possible in hope that the submaximal (‘good enough’) level, as well as the robustness of the movement, will increase together with the maximal level. The maximal level raises the submaximal level along with it, as it were.”
“One which primarily seeks to increase the robustness of the movement, so that the ‘good enough’ level then shifts towards maximal level without the maximal level needing to rise”
Quotes from- Frans Bosch (2010) Strength Training and Coordination: An Integrative Approach
This week we dove into discussion of the knee joint, and why is desires STABILITY. Let’s revisit some of the points and concepts discussed, a go a little bit deeper.
It started with understanding a very important concept
EACH joint has ratios of inherent bony stability to soft tissue stability (or dynamic stability). Generally speaking, joints that have more bony stability crave mobility, and vis versa. So let’s take a look at the knee: