Today’s episode features Justin Moore.  Justin is the head performance coach at Parabolic Performance and Rehab in Montclair, New Jersey.

Justin has worked with athletes of all ages and abilities, from eight-years-old to professional football players in the National Football League (NFL) and Olympic-level Ice Skaters and Ice Dancers.  He has been highly involved in the process of helping elite college football players prepare for the NFL Combine.  Justin also has advanced knowledge of the concepts of PRI as well as Bill Hartman and other elite coaches, giving him a very thorough lens by which he observes the body in training.  He has previously appeared on this podcast twice, on episodes 78 and 124.

An area of biomechanics and sports performance that is (thankfully) getting more attention is the internal rotation and “knees in” phenomenon that all of the great jumpers in the world utilize (albeit to varying degrees).  If the knees don’t travel inwards in a reactive jump, then elastic energy transfer is lost and an athlete also loses the ability to create a strong triangle structure with their feet and legs.

The question with the “knees in” equation is “when does it become a problem”?  A large amount of athletic performance programs will simply try to coach all athletes into a robotic motion where the knees don’t travel inwards at all in an attempt to avoid injury (and also assuming that the knees traveling inwards is the problem in all athletes) and in the process, rob them of elastic power.  As with anything, there is a bandwidth, just like the concepts of pronation.  Pronation is good, while being stuck in pronation is bad.

To fully understand when the natural and effective internal rotation and “knees in” can become an issue, Justin Moore gives us a thorough explanation, as well as many case study anecdotes.  In this episode, Justin uses a lot of fluid dynamics examples, and takes a lot of work from Bill Hartman to explore deeply this corner of human performance.  This episode is quite intensive and is one of those shows that you truly can study, since the material is quite foundational to the way we observe and train athletes.

Today’s episode is brought to you by SimpliFaster, supplier of high-end athletic development tools, such as the Freelap timing system, kBox, Sprint 1080, and more.







Key Points

Basic mechanics of why knees will rotate in during jumping and squatting from a perspective of pelvic mechanics and thorax hydraulics
How to determine when “knees in” is potentially excessive or problematic and how to approach it
Where to start: feet vs. the hips when there is knee pain in an athlete
Use of the modified Ober’s test to assess adduction capability of the femur
How pressurization of the trunk impacts an athlete’s ability to produce force versus having movement options
How being internally or externally rotated in the femurs can impact standing versus multi-jump performance






Quotes
“We see this (knees in strategy) from the best athletes in the world… when you look at the best lifters in the world, they all do it, when you look at the best jumpers in the world, they all do it”

“As I begin in a standing position, and I descend into a squat, I am going to be externally rotating, and I am going to be inhaling and expanding, and my pelvic floor is going to be descending.  When I hit the sticking point, what I am going to see is a reversal of that.  I am going to see internal rotation, I am going to see exhalation, compression, and ascension of the pelvic floor”

“The pelvic floor ascending is propulsion… it is shooting my guts back up into my thorax as I exhale”

“When I look at somebody who is jumping, I see an individual who is utilizing an internal rotation and adduction moment of the femurs in order to allow them to open the pelvic outlet which allows me to ascend the pelvic floor…. It is a propulsive strategy”