Performance Testing at AL: Turning Data Into Direction
“The value of performance testing is being able to identify, measure, and track changes over time.”
At Alpine Performance Labs we collect and analyze data to add multiple dimensions to our decisions. Our diagnostic tools aren’t gadgets and gimmicks, but feedback loops that help us align training with the athlete’s unique profile, injury history, and performance goals.
Since opening, one of the most valuable tools in our system has been the Hawkin Dynamics force plates. Portable, quick, and non-invasive, they give us a digital signature of how an athlete moves both in their lower and upper body.
Why the Countermovement Jump (CMJ) Is Our Go-To
Every athlete that walks through our doors for training starts with a hands-on-hip CMJ. This single movement gives us rich, high-resolution data that informs:
- Where the athlete has been (training history or deconditioning)
- Where they are now (readiness, asymmetry, neuromuscular profile)
- Where they could go (trainability, areas of focus, power potential)
What We’re Looking At: Interpreting the CMJ
Here’s a snapshot of the key metrics we analyze, and why they matter:
Power & Explosiveness
- Jump Height (in): Core indicator of vertical power. Tells us how well you express force.
- Avg. Relative Propulsive Force (%): Measures force output during takeoff—directly reflects lower-body explosiveness.
- Braking RFD (N/s): How fast you can absorb and reverse force. High values = fast neuromuscular reactivity.
Movement Strategy & Timing
- Time to Takeoff (s): How fast you transition from loading to propulsion. Slower times may indicate caution, fatigue, or inefficiency.
- mRSI (Modified Reactive Strength Index): Jump height ÷ time to takeoff. Captures how efficiently you explode.
- Countermovement Depth (in): Deeper dips may allow more elastic energy storage—but can also point to mechanical compensation.
Eccentric Strength & Control
- Avg. Relative Braking Force (%): Reflects how aggressively you control your descent. Key for ACL/hamstring rehab monitoring.
- Force at Min Displacement (N): Measures eccentric strength at the bottom of the jump—essential for change of direction sports and deceleration capacity.
- Impulse Ratio: Braking impulse ÷ propulsive impulse. Values near 1 = good efficiency; values far from 1 = mechanical mismatch.
Asymmetry & Injury Risk Indicators
- L:R Braking Force (%): Left–Right balance during deceleration. >10% difference may indicate past injury or rehab need.
- L:R Propulsive Impulse Index (%): How equally each leg contributes to push-off. Dominance may signal performance leak or compensatory strategy.
- Relative Peak Landing Force (%): Excessive landing force can flag poor mechanics or elevated injury risk post-fatigue.
Tracking Progress = Better Coaching Decisions
We repeat these tests periodically to track:
- Rehab progressions (e.g., after ACL, hamstring, or Achilles injury)
- Power development from targeted blocks
- Neuromuscular fatigue or compensation patterns over time
- Readiness scores for high-stakes efforts or return-to-play
What We See Most at APL
Force Plate Trends from the Field
Over the past several months, we’ve collected force plate data from dozens of mountain athletes, spanning diverse sports and training backgrounds. While every athlete’s “signature” is unique, certain patterns show up again and again—giving us insight into what’s common, what’s limiting, and where we can make the biggest impact.
Without publishing the raw data, here’s what we’re seeing most often, compared to standard athlete norms:
Metric | Compared to Norms | Trend |
Jump Height | ↓ | Lower than typical field/court athletes → Indicates limited concentric power or jump efficiency |
Time to Takeoff | ↑ | Longer transition phase → Suggests slow stretch-shortening cycle or excessive braking |
mRSI | ↓ | Underdeveloped elastic response → Athletes often “load deep, jump soft” |
Braking Rate of Force Development (RFD) | ↓ | Slower deceleration → Eccentric power is a limiter in most mountain athletes |
Propulsive Force | ↓ | Lower peak force → Indicates low system tension or reduced explosive capacity |
Impulse Ratio | ↑↑ | Over-braking relative to propulsion → Common in athletes with stiffness-dominant or fatigue-limited profiles |
Landing Forces | ↑ | Many land with excessive force → Often a sign of undertrained eccentric capacity or fatigue-based compensation |
Force at Bottom of CMJ | ↓ | Lower-than-expected eccentric strength → Particularly common in athletes returning from off-season or injury |
Asymmetry (Braking & Propulsive) | ↔︎ to ↑ | Mild to moderate L/R bias → Directionally consistent side dominance shows up often (post-injury, sport-specific patterns) |
What This Means for Coaching
Most APL athletes start with solid general strength but present with:
- Underdeveloped eccentric reactivity
- Slower force transfer
- Poor elastic efficiency
- Asymmetry that’s subtle but consistent
In practical terms, this means we’re not just “building strength”—we’re targeting how quickly and efficiently that strength is expressed, particularly under load, fatigue, or uneven terrain.
Why This Matters for Mountain Athletes
- Eccentric control and landing forces reveal how well an athlete can absorb load—critical for long descents, uneven terrain, and injury resilience.
- Time to takeoff and mRSI highlight an athlete’s ability to move quickly and efficiently under dynamic conditions—essential for on-trail reaction, snow transitions, or technical climbs.
- Braking and propulsive asymmetries expose side-to-side imbalances that can increase risk or limit performance over long efforts or with fatigue.
- Low jump height and propulsive force often reflect an athlete who can “grind” but lacks top-end output or elastic reactivity—a common limiter in endurance-focused profiles.
- High impulse ratios and landing forces flag athletes who may brake too much and rebound too little, costing them energy and efficiency in rugged environments.
Coach’s Note
“Testing provides actionable insights to help us provide meaningful results.”
— Danny Blake, M.S. Kinesiology, CSCS, C*ISSN
CEO & Head Coach, Alpine Performance Labs
Want to Know What Your Jump Says About You?
We offer standalone performance diagnostics or full training consults that include a CMJ profile, movement screen, and force plate interpretation.
