Single-Leg RSI Predicts Sprint Ability

Richard Burnett is a sports performance coach with experience working across high-level athletic environments, including NFL Combine preparation, where he specializes in speed and power assessment, plyometric development, and preparing athletes for elite testing and competition. In this episode, Rich Burnett digs into reactive strength testing, jump feedback, and what really matters when evaluating plyometric ability in athletes. Rich explains the differences between tools like the Just Jump mat, force plates, and Plyomat, emphasizing that context and consistency matter more than chasing perfect numbers. The conversation then moves into single-leg RSI, asymmetries, NFL Combine prep, and how reactivity profiles can reveal sprint deficiencies. Rich also shares how he uses isometrics, band-assisted jumps, and single-leg testing to build faster, more explosive athletes with greater confidence and movement efficiency. Today’s episode is brought to you by Hammer Strength. Use the code “LILAJUSTFLY10” for 10% off any Lila Exogen wearable resistance gear. For this offer, head to Lilateam.com Use code “justfly10” for 10% off the Vert Trainer View more podcast episodes at the podcast homepage. (https://www.just-fly-sports.com/podcast-home/) Timestamps 0:00 – Introduction to Jump Testing 4:55 – Context in Performance Metrics 8:11 – The Psychology of Feedback 11:59 – Transition to Combine Training 16:10 – The Importance of Single Leg Testing 20:06 – Analyzing Reactive Strength Index (RSI) 32:02 – Asymmetry in Athletic Performance 36:24 – Gamifying the Test 44:59 – Band-Assisted Techniques 55:30 – The Power of Isometrics 1:01:51 – Single Leg Reactivity Insights 1:07:08 – Exploring the Plyomat Richard Burnett Quotes "As long as you're using a piece of tech consistently and coaching well and all the things are the same, that's really what it's all about. That's why Mike Boyle still uses the same deal from 15 years ago and will continue to use the same one because he knows what it's telling him." "The more information you start to uncover the more context you need. Whether it's inflated or not, I know like a 40-inch standing vert on the Just Jump mat is legit. And I also know a 36-inch is good. It still provided us with some key context to allow us to track improvement." "I love RSI as a teaching tool. It's fantastic because a lot of kids don't understand. It's still gluing us in to what's going on with the athlete, how their strategies are. It's helping them understand plyometrics to begin with." "It's also from a symmetry thing, really enlightening to see the difference between a left leg and a right leg when you're testing them independently. You're like, 'wow, that is a massive difference.' And let's remember the fact that this athlete has had two ACLs on this side." "Single leg ground contact time and why you do some of these single leg reactivity drills in the first place because you're dealing with mass in your whole body on one leg. Contact time being rewarded in that sense is not necessarily a bad thing at all. And we're just seeing this clear separation of some of our athletes because of their ability to be more reactive on one leg." "DRI factors in automatically what your initial jump height is. I love it because they want to self-select that. As opposed to stepping off of a box that you just maybe don't feel as confident in, self-selecting that initial jump and then rebounding just feels more confident, feels more engaging and fun for kids." "What I had seen is a really high correlation with single leg max RSI and sprint ability in athletes. Higher than force plate jumps, higher than pretty much anything else." "The step further is now the cyclical five hop where I'm having to really tolerate all of this landing force from my own jump height that I'm creating on the single leg five hop RSI. That's the one that I'm wanting to really flesh out even more to know who's lacking reactivity." "The sprinting is enough for them to get that midfoot forefoot work but there's no real need to specify some sort of plyo around that when they're sprinting already and we sprint so much." About Richard Burnett Richard Burnett is a sports performance coach and the creator of Plyomat, an innovative training system designed to enhance plyometric development, coordination, and reactive strength across a wide range of athletes. With a coaching approach rooted in movement quality and progressive overload, Burnett has built a reputation for blending traditional jump training principles with creative, constraint-based environments that challenge timing, rhythm, and elastic output. His work emphasizes not just how high or far an athlete can jump, but how efficiently they can organize force, absorb impact, and transition between movements. Through Plyomat, Burnett has introduced a practical framework for integrating plyometrics into both high-performance and general athletic settings, offering coaches a scalable system that supports everything from foundational movement literacy to advanced explosive training. His ideas and methods have been adopted by coaches working in team sports, track and field, and youth development, particularly those looking to bridge the gap between structured strength training and dynamic, game-relevant movement.