You’ve done your rehab. Your knee feels strong. You can hop, squat, and lunge without pain. Your physio has cleared you to return to sport. Everything seems fine.
But here’s what you can’t feel: your injured leg is producing 15% less force than your other leg when you land from a jump. Your brain has compensated so well that the movement looks symmetrical. You feel balanced. But your body knows the difference, and that difference quadruples your risk of re-injury.
This is the gap between how you feel and what your neuromuscular system is actually doing. It’s why athletes who pass traditional clinical assessment still get injured. And it’s exactly what VALD force plate and dynamometry testing is designed to reveal.
In this article, you’ll learn why asymmetries above 10% matter, how force plate testing detects what standard assessment misses, and why objective data could be the difference between staying active and facing another injury.
WHAT IS VALD TESTING?
VALD (Vald Performance) testing uses force plates and dynamometry to measure exactly how much force your muscles produce, how quickly they produce it, and whether both sides of your body are working equally.
Unlike standard strength testing where a physio watches you perform a movement and makes a subjective assessment, VALD testing provides objective, quantifiable data on:
– Peak force production (how much force you can generate)
– Rate of force development (how quickly you can generate force)
– Limb symmetry index (whether both sides are equal)
– Force-time characteristics (the shape and quality of force production)
– Movement strategy (how your body compensates)
The most common VALD systems used in clinical practice include:
FORCEDECKS: Dual force plates that measure ground reaction forces during jumping, landing, and balance tasks. These reveal asymmetries in how you absorb and produce force.
NORDBORD: Measures eccentric hamstring strength, a key predictor of hamstring injury risk.
FORCEFRAME: Measures isometric strength in multiple positions, including hip strength, adductor strength, and groin stability.
These systems don’t just tell you if you’re strong. They tell you if you’re strong enough, if both sides are equal, and if your neuromuscular system is functioning optimally.
WHY ASYMMETRY MATTERS (EVEN WHEN YOU CAN'T FEEL IT)
Your brain is exceptional at compensation. After an injury, it learns to shift load, alter movement patterns, and recruit different muscles to keep you moving without pain. This is protective in the short term, but problematic long term.
When limb symmetry drops below 90% on hop testing, the risk of ACL re-injury in the first two years quadruples. Four times the risk. Not a small increase.
But here’s the critical part: most people can’t feel a 10% difference in force production between limbs. Movement looks symmetrical. It feels symmetrical. But the data shows it isn’t.
In professional football players, countermovement jump asymmetry above 10% predicts hamstring injury with 86% sensitivity. This means force plates can identify 86 out of 100 athletes who will go on to get injured, based purely on asymmetry data.
Standard clinical assessment misses this. A physio watching you hop might see symmetrical movement. But the force plate reveals that your injured leg is absorbing 12% less force on landing, meaning your other leg is overloaded. Over time, this asymmetry creates injury risk on both sides.
THE RESEARCH: WHAT THE DATA SHOWS
The evidence for VALD testing in injury prevention and recovery is substantial. Here’s what we know:
LIMB ASYMMETRY AND RE-INJURY RISK
Athletes who achieve less than 10% limb asymmetry on VALD ForceFrame testing before return to sport have 73% lower re-injury rates compared to those cleared on clinical criteria alone.
This is the critical finding. Traditional assessment focuses on whether you can perform a movement without pain. VALD testing focuses on whether you can perform it with equal force production on both sides. The difference in re-injury rates is stark.
HIP STRENGTH AND LOWER LIMB INJURY
Isometric hip strength asymmetry above 15% increases the risk of lower limb injury in runners by 2.6 times.
Hip strength asymmetries don’t just affect the hip. They alter pelvic mechanics, change loading patterns through the knee and ankle, and increase injury risk across the entire kinetic chain. But unless you measure it objectively, you won’t know it’s there.
ECCENTRIC HAMSTRING STRENGTH AND STRAIN RISK
Eccentric hamstring strength below 3.0 Newtons per kilogram of body weight is associated with 4.4 times increased hamstring strain risk in elite athletes.
This gives us a specific threshold. Not “you need stronger hamstrings.” But “if your eccentric hamstring strength is below 3.0 N/kg, your injury risk is significantly elevated.” That’s actionable data.
FORCE PRODUCTION QUALITY, NOT JUST QUANTITY
Force-time curve characteristics—impulse and rate of force development—provide more sensitive markers of neuromuscular recovery than peak force alone. These metrics detect deficits in 34% of athletes who pass traditional strength testing.
This is why VALD testing matters. You might be able to produce enough peak force to pass a standard strength test. But if your rate of force development is slow, or your force-time curve is abnormal, you’re not fully recovered. The injury risk remains.
WHAT STANDARD ASSESSMENT MISSES
Traditional clinical assessment relies on:
– Visual observation of movement quality
– Manual muscle testing (physio resistance)
– Functional tests (hop, squat, lunge)
– Subjective reports of pain and confidence
These are valuable. But they’re subjective, and they miss critical data.
VALD testing reveals:
ASYMMETRIES BELOW CONSCIOUS AWARENESS: You can’t feel a 10% difference in force production, but your body experiences it with every landing, every cut, every acceleration.
RATE OF FORCE DEVELOPMENT DEFICITS: Rate of force development deficits persist for six to nine months post-ACL reconstruction despite achieving 90% limb symmetry on peak force. This means you might be strong enough, but your neuromuscular system isn’t fast enough. Standard testing won’t flag this.
COMPENSATORY MOVEMENT STRATEGIES: Force plates show exactly how you’re compensating. Are you shifting weight to one side during landing? Is one leg absorbing more force? Are you using your quads more than your glutes? The data reveals the strategy.
BILATERAL DEFICITS: Sometimes both sides are weak, but symmetrically weak, so standard testing doesn’t flag it. VALD testing compares your data to normative values for your sport, age, and activity level, revealing whether you’re strong enough overall, not just symmetrical.
INTERNAL CLINICAL CONTEXT: THE NERVOUS SYSTEM AND INJURY RISK
Injury isn’t just about tissue damage. It’s about neuromuscular control.
When you injure a knee, ankle, or hamstring, the nervous system alters motor control patterns. Muscle activation timing changes. Proprioception decreases. Force production becomes asymmetrical. This is protective initially, but if it persists, it becomes a risk factor.
VALD testing provides objective feedback to the nervous system. When you see your force production data, your brain has a target. When you can track improvement session to session, your nervous system recalibrates. This is part of why objective testing improves outcomes. It’s not just about the data. It’s about giving the nervous system clear, measurable goals.
This connects to broader principles of recovery optimisation. Nervous system regulation, metabolic health, and tissue healing all interact. If systemic inflammation is elevated, if sleep is poor, if stress is high, neuromuscular recovery will be slower. VALD testing can reveal when recovery has stalled, prompting investigation into what else might be holding you back.
FAQ's
No. Most people cannot consciously detect asymmetries below 15-20%. A 10% difference in force production feels normal. Your brain compensates automatically, shifting load and altering movement patterns to maintain symmetry of effort, even though symmetry of force is lost. This is why objective testing matters.
It depends on the injury and the quality of rehab. Rate of force development deficits can persist for six to nine months post-ACL reconstruction, even when peak strength has returned to 90% of the uninjured side. Without targeted intervention, some asymmetries can persist for years.
No. VALD testing is valuable for anyone returning to activity after injury, anyone with recurrent injuries, and anyone wanting to understand their injury risk. Runners, active adults, weekend warriors, and post-surgical patients all benefit from objective data on neuromuscular function.
If testing reveals asymmetry above 10%, the focus shifts to targeted strengthening, neuromuscular re-education, and movement retraining. The goal is to bring asymmetry below 10% before returning to high-demand activity. This significantly reduces re-injury risk.
Yes, to a degree. Specific thresholds predict injury with high accuracy: eccentric hamstring strength below 3.0 N/kg, adductor strength below 45% of body weight, and countermovement jump asymmetry above 10% all indicate elevated risk. Testing can identify athletes at risk before injury occurs, allowing preventive intervention.
CONCLUSION
The asymmetry you can’t feel is the asymmetry that matters most.
You can pass every standard clinical test, feel strong, move without pain, and still be at significantly elevated injury risk if your force production is asymmetrical. Asymmetries above 10% quadruple re-injury risk. Athletes who achieve less than 10% asymmetry before return to sport have 73% lower re-injury rates.
VALD force plate and dynamometry testing provides the objective data standard assessment misses. It reveals how much force you produce, how quickly you produce it, and whether both sides are equal. It detects neuromuscular deficits in 34% of athletes who pass traditional strength testing.
If you’ve had a significant injury, if you’re returning to sport, or if you keep getting injured despite doing your rehab, VALD testing could reveal what’s been missed.
Your body knows the difference, even if you can’t feel it. The data shows it clearly.
REFERENCES
1. Systematic Review (2020) – Limb Symmetry Index and ACL Re-injury Risk
2. Prospective Cohort Study (2019) – Countermovement Jump Asymmetry and Hamstring Injury Prediction
3. RCT (2021) – Hip Strength Asymmetry and Lower Limb Injury Risk in Runners
4. Comparative Study (2022) – VALD Testing and Re-injury Rates Post-Return to Sport
5. Longitudinal Study (2023) – Rate of Force Development Deficits Post-ACL Reconstruction
6. Comparative Study (2023) – Force-Time Curve Characteristics and Neuromuscular Recovery
7. Meta-analysis (2020) – Eccentric Hamstring Strength and Strain Risk
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