Rate of Force Development (Early versus Late)

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).

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Muscle Slack and High Velocity Training: An Integrative Approach

Velocity Deficient

 

The idea of measuring and training for velocity deficiencies has become popular since the recent studies of JB Morin and colleagues. In one of their studies, they examined several different subjects and based on their profiling methods, determined whether or not the individuals had a force-velocity profile that was either velocity deficient or force deficient. Once the deficiency was determined, the subjects were trained using specific methods emphasizing the velocity component of the movement (slow velocity for max force and fast velocity for speed of movement). After the study’s training cycle, J.B Morin and colleagues were able to show that the specific training methods, either slow or fast, improved vertical jump performance and overall balance of the subjects’ force velocity profiles.

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KINETIC HYGIENE: THORACIC MOBILITY SUMMARY

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This week, we explored arguably one of the most significant areas of the body when it comes to contributing to pathology.

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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.

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Training Elasticity (Reactivity)

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.

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What Are We Testing?

Assessing athletic development can be done in an assortment of ways. Typically, such assessment is done by testing maximal strength in a movement, dynamic strength in a movement, and possibly some other type of “sport specific” movement. There is nothing wrong with this type of testing, but it can leave the coach asking some questions.

One of the issues with this style of testing is that it may not give enough “insight” to the development of the athlete. Every movement has many variables that influence its performance and it is hard to discern whether or not those variables are influencing the outcomes of the tests. Typically, such variables arise most often in a “dynamic” style of testing.

Why Test

It is important to understand why testing is done. Testing is done to help guide a training program, which means the more accurate the testing is, the better of an idea the coach will have at pinpointing areas of improvement. Granted, any form of barbell/weight room testing is relatively non-specific, it can still provide insights into possible “general” physiological and neurological qualities that influence performance.

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