Hello everyone, Joe from LEOMO here. Today I want to go over an analysis of the Power Clean movement and how to improve technique.
The power clean is a high speed, high power, technically demanding exercise. The goal is to increase power production, and specifically our vertical power production. Because of this, optimizing technique is important not only to ensure we are achieving our target power output, but also to ensure we are maximizing our power into the vertical direction.
Dylan is a professional obstacle course racer and an experienced strength and conditioning coach.
He’s a proficient lifter, but wants to take a closer look at optimizing his power clean technique to enhance his training and discover areas where he can improve his power production.
Purposes of Analysis:
Optimizing his power clean is going to allow him to generate more power in his training sessions and reduce the risk of errors in his movement.
Let’s start with a breakdown of the key phases of the power clean:
1st Pull: This phase consists of the first movements of this exercise, from starting position up until the bar is just below the knees.
Transition: During this phase the bar will slide to above the knees and the athlete will shift their hips forward beneath the bar and their torso into a vertical position.
Second Pull (Power Phase): This is the key component of this movement. During this phase the athlete will quickly extend the hips, knees, and ankles to forcefully propel the bar vertically and then proceed to the catch (because we are only focused on the power production of this movement today, we will skip the catch phase in this analysis).
Dylan’s Sensor Placements:
Feet (tops of laces): to measure plantarflexion velocity (although this is not the key focus of our analysis today).
Pelvis (sacrum): to measure trunk angle maintenance and peak pelvic acceleration.
Torso (sternum): to measure and compare timing of pelvic peak acceleration and torso peak acceleration.
Dylan’s Key Sensor Outputs:
Pelvis GyroX: this will show us angular velocity in the sagittal plane of the pelvis. This is useful in determining hip extension angular velocity and also detecting when undesirable movement is present.
Pelvic H-Angle: this will give us a measure of the pelvic angle relative to the ground. This is useful in measuring hip angle maintenance through the first pull especially, as well as determining how well the athlete is achieving a vertical position before the power phase.
Pelvis Acc Y: this will give us a timestamp of when the highest vertical acceleration of the pelvis is achieved during the power phase.
Torso Acc Y: similar to pelvic acceleration Y above, this will give us a timestamp of when the highest vertical acceleration of the torso is achieved during the power phase. Together, both of these acceleration measures tell us how well an athlete can synchronize both components to achieve maximal vertical power output.
1st Pull: what we notice during Dylan’s 1st pull is that he is not maintaining a constant torso angle as he begins the movement. We can see his hips tilt forward as they rise faster than the rest of his torso. The key indicator here is the Pelvic GyroX sensor output. Here we see a positive deviation above the zero line in LVS. This indicates the sensor is picking up an anterior tilting of his pelvis. Ideally we want to see his hips maintain a constant angle to the ground during this phase and if done properly, there will be no Pelvic Gyro X increase. If we look at the H-Angle output from the Pelvic sensor, we see he is on average tilting his pelvis about 21° forward during the 1st pull.
Above we see a good starting position.
Immediately when the 1st pull begins, the hips rise faster than the torso. This causes the entire trunk to tilt forward, reducing reliance on the quadriceps and shifting more reliance to the posterior chain.
Dylan has shifted his hips farther away from the bar, which will be a crucial detail in the transition phase (next).
Transition: As Dylan progresses through the transition phase, due to the rise of his hips during the first pull (moving his hips away from the bar), he does not have enough time to shift his hips fully under the bar to achieve a vertical position with his torso.
Due to this, he will have to continue to rotate towards a vertical position as he begins his upward acceleration in the power phase. This will result in an offset of maximal acceleration between the pelvis and torso, and a reduction in vertical power.
2nd Pull: During the power phase, our goal is to maximize vertical power. We want to create the highest acceleration from both the pelvis and torso, simultaneously.
Our blue line here displays the Acceleration Y component of the Torso (measured from the sternum). The red line displays the Acceleration Y component of the Waist (measured from the pelvis). Above we see the peak vertical acceleration of the torso achieved as Dylan continues rotating into a vertical position.
Several milliseconds later, we see the peak vertical acceleration from the pelvis. This occurs as Dylan begins to quickly accelerate through his triple extension and propel the bar vertically.
Because these two maximal accelerations are offset from one another, the peak vertical power will be reduced.
In order to improve this, we will focus on maintaining a constant torso angle through first pull, not allowing the hips to rise faster than the rest of the torso. This will position the hips closer to the bar at the start of transition, which will allow Dylan to achieve a more vertical position with the hips under the bar at the start of the power phase. This will improve maximal vertical power through the power phase by better synchronizing hips and torso peak acceleration.
After some data review and technique breakdown with Dylan, the next round of power cleans the following week showed marked improvements.
This time during the 1st pull (above), we see the total forward tilting of the trunk reduced to about 12°. This displays positive change from the 1st session where we observed 21° of total tilt. We will keep working on this until we are able to minimize this forward tilting completely.
This positions Dylan in a much more favorable position relative to the bar during the transition phase. This allows for improved synchronization of the maximal accelerations from the pelvis and torso during the power phase.
Looking at the power phase, we can now see the Waist (red) and Torso (blue) Acceleration Y components synchronizing much better with one another. This indicates we have improved in our goal of maximizing vertical power output.
Joseph Cavarretta, MS, ACSM-EP
LEOMO Sport Scientist & Coach