Hawkins Jump Metrics - What Really Matters + What Does It Mean
Jumping. It’s one of the most primal, impressive, and fundamental movements we know. From the time we're kids asking "How high can you jump?" to watching elite athletes defy gravity, a good jump never fails to inspire awe. But here’s the secret every high-performer knows: jump height is just the trailer. The real story, the metrics that dictate true power and safety, are hidden from the naked eye.
For those of you looking to maximize your performance—whether you're an athlete, a coach, or just a human obsessed with efficiency—it's time to go beyond the tape measure and into the nuts and bolts of force production.
Here are the three jump metrics that are truly moving the needle:
1. mRSI (Modified Reactive Strength Index)
Think of mRSI as your athletic quickness meter. It's the ultimate measure of explosiveness.
- What it is: The Modified Reactive Strength Index (mRSI) is calculated simply by dividing your jump height by your ground contact time.
- What it means: It shows how quickly you can produce a significant amount of force. The higher your mRSI, the faster you are able to transition from absorbing force (landing) to producing force (jumping off).
- Why it matters: This is highly sensitive to fatigue, making it a powerful monitoring tool. Crucially, a high mRSI has huge implications for your Change of Direction and agility. In sports and life, it’s not just about being strong; it's about being strong fast.
2. Jump Momentum
Momentum is your measure of vertical launch efficiency, but it has a surprisingly direct link to your upper body strength.
- What it is: Calculated by multiplying your takeoff velocity (how fast your body is moving vertically at the point of liftoff) by your body weight.
- What it means: This metric dictates your overall efficiency. It's about how effectively you use the ground to propel your entire body mass upwards.
- Why it matters: Getting better at using the ground to accelerate your body vertically in a jump directly translates to standing upper body movements like pressing and rowing. Why? Because you’re improving your ability to stabilize, transfer force through your core, and utilize the kinetic chain—skills that apply to any standing lift.
3. Net Braking Impulse
This is arguably the most critical metric for career longevity and injury prevention. It’s all about the brakes.
- What it is: The amount of force applied over the amount of time during the braking phase of a jump, relative to your body weight. It is measured in Ns/kg.
- What it means: In simple terms: how much force—relative to your own body weight—can you produce to change directions or stop a dynamic movement?
- Why it matters: Net Braking Impulse tells us how well an athlete is at stopping and controlling force and stabilizing a dynamic movement. An inability to effectively decelerate and control your body weight is the root cause of many non-contact injuries seen in sports. If you can't stop safely, you can't push your limits safely. Mastering this metric is a non-negotiable for long-term health and performance.
The vertical jump is a classic benchmark, but true excellence lies in the data you can't see. By tracking and improving your mRSI, Jump Momentum, and Net Braking Impulse, you’re not just jumping higher—you’re becoming a faster, more efficient, and more durable athlete.
