Strength in Numbers #197
Baseball players are evaluated heavily both on and off the field.
In relation to the lower body, force plate analysis has emerged as a critical tool, proving effective in evaluating the eccentric phase of the vertical jump.
If you don’t understand force plate analytics, we cover it in detail within our ArmCare Elite Education. I’m building three more mini-courses on it now. If you’re interested in getting access, once you register for our Certification Bundle, you’ll unlock your ArmCare Elite Membership.
The research I have been involved in at the Human Performance Laboratories at Louisiana Tech is a baseball sports science mecca, and we dive deep into indicators of elevated rates of loading on the inner elbows of pitchers during their delivery.
None more eye-opening than a surge in lower-body power.
Getting back to the eccentric phase is essential, as it reflects an athlete’s ability to absorb force and store elastic energy – pretty darn important when you are moving fast down the slope and have to manage the gravitational multiplier of body mass and its acceleration into stride foot contact.
This phase ends just before the concentric (upward) motion of the jump, when the muscles lengthen under load to prepare for take-off. It plays a pivotal role in determining the stretch-shortening cycle (SSC) efficiency, which is directly linked to explosive power output for the throwing arm.
Think of this… slamming on the brakes is one thing, but some athletes will spring off the ground while their throwing arm is accelerating toward the catcher.
They utilize the eccentric (elastic loading) features of the lead leg to essentially pole vault the lower body and accelerate the throwing arm, which acts as the catapult, into a higher ball release finish with greater arm speed and throwing velocity.
You need to know more about this key metric to ensure the ground reaction force system is in check when jumping.
And if you’re into these key concepts and deep technical insights into bulletproofing arms, then be sure to join us in person at one of our ArmCare Accelerator Events. It’s an awesome opportunity to connect with like-minded professionals and stand out from the crowd.
Something like “Learn key concepts and deep technical insights into bulletproofing arms – separate yourself from the pack and join us in person at one of our ArmCare Accelerator Events.”
Evaluating the Eccentric Phase with Force Plates
Force plates give us granular insights into an athlete’s ability to absorb force during the downward motion of a jump. This is referred to as absorption power—a reflection of how well the body decelerates and transitions energy for propulsion.
There are two force stories that athletes have to build – one in deceleration and another in acceleration, which lead to sustainable power.
- FORCE ABSORPTION: High relative absorption power values typically exceed 30–35 W/kg in elite-level athletes. What does this mean? Just like our ArmScore, comparing athletes at different power levels requires us to consider how powerful they are relative to their body size. Ideally, we want our athlete’s absorption power, a measure of deceleration, to be high and for our throwing arm force relative to body weight, as measured by our ArmScore, to be high. This adds to the durable arms and sustainable performance.
- FORCE GENERATION: On the opposite spectrum is another type of power, one that accelerates the body in the intended direction to complete a throw. Efficient eccentric strength (loading) and timing in the stretch-shortening sequence, when muscles stretch and then recoil, correlate with greater concentric power output. This means athletes can jump higher, faster, and with less wasted effort when the elastic bands in our bodies are stretched optimally and recoil explosively. When athletes can absorb forces quickly, the concentric power they generate by pushing off the floor should be more than twice the relative absorption power in the eccentric phase. In the previous example, something over 70 W/kg would be good.
This simple diagram illustrates the phases of the vertical jump. Point A is the starting point, but from just after A until Point E is the eccentric phase, where the absorption power (vertical jump force x vertical jump velocity) is negative, and muscles are contracting as they are being lengthened, so the body doesn’t fall through the floor. The concentric phase, where muscles shorten when they contract, starts just after Point E and goes just before Point G. As you can see, we need to LOAD (phases A-E) before we EXPLODE (phases E-G), and that means the eccentric phase metrics are more important to understand as it relates to raising jump force, jump velocity, jump height and injury protection.
Our ArmCare Elite Course on force plate analytics elevates our ACE Members as we go through the phase details, paired with video, to give our students a proper understanding of how to evaluate countermovement jump properties. This enriched educational experience is designed to keep our students ahead of the curve and avoid being overwhelmed by the forced-time graphs that are a mainstay in the 3D biomechanics world.
The Eccentric Connection to Pitching Performance
Here’s where it gets interesting for baseball pitchers.
The pitching delivery—particularly during the stride and rotation phases—also relies heavily on stretch responses in the lower body. An efficient lower-body eccentric load helps store elastic energy that gets transferred up the kinetic chain into the trunk and arm. This improves pitch velocity, but also increases the demands on the elbow, especially the ulnar collateral ligament (UCL).
Research has shown a connection between Tommy John injuries and the eccentric rate of force development, specifically the speed at which the loading force is applied (N/s). Combined with findings published by Louisiana Tech, studies suggest that low eccentric strength and high jump power surges are strong links to improving high-rate torque applications at the elbow.w
This means that athletes with low eccentric force output, that may result in low eccentric power, combined with producing high vertical jump power, an indicator that the athlete is likely concentrically strong, may increase greater elbow varus torque rates—and without adequate throwing arm strength, the injury risk escalates, especially when it comes to three-finger grip strength.
People often read force plate data with a focus on force, yet there is an important interchange between force and velocity. When multiplied together, we calculate the athlete’s vertical jump power.
If force is high and velocity is low, there may not be a shift in power compared to low force and high velocity jumpers. However, when we see velocity enhancement in training that does not include weighted balls, the velocity is coming from increased absolute power, meaning the athlete is not only gaining lean mass but also increasing their contraction speeds to become more explosive.
Given that research supports the theory that the rate of torque application (how quickly torque builds during the throw) may be a more critical injury factor than maximum torque alone, greater lower-body power generation must be matched with routine arm strength testing to ensure the body is prepared for the stresses of high-output throwing.
To augment throwing arm health, I often say, “Train the Brakes so you don’t break,” and this concept applies to our lower body. If we do not improve the way our lower body decelerates when applying braking force, storing less elastic energy is a potential pitfall, and less negative power is generated for transfer to the upper extremities.
In our Accelerator Courses, we dedicate a section to Run, Jump, and Throw training, three important areas essential for high-powered arms that throw healthily. If we cannot coach our athletes to produce force with short ground contact (less than 150 ms), cannot improve their ability to absorb or generate power from the ground, and have inefficient throwing arm strength characteristics, injury prevention and rehabilitation efforts will be futile.
More explosive athletes need more intensive monitoring. In this ArmCare Elite Scrum, we are trying to get you to huddle up with your coaches, sports medicine specialists, and players to create an evaluation process. Typically, athletes with big absolute jump power exhibit higher loading rates and magnitudes of force at the inner elbow.
Conclusion: Test More, Train Smarter
Suppose you’re building vertical jump power to boost on-field performance—great. But make sure your athlete’s throwing arm is conditioned to handle the downstream effect of these gains. Regular arm strength assessments and workload customization are essential.
Understanding eccentric mechanics through force plate analysis not only improves jump performance but can also help prevent serious injuries, such as Tommy John Surgery. By pairing lower body force diagnostics with arm-specific strength tracking, we can help athletes reach new levels safely.
If you’re enjoying the course snippets and accelerated learning, join us and check out our course bundles and in-person Accelerator events near you!
Strength Matters Most,
Ryan
