Biodex:

Understand your joint and muscle strength to optimize performance, prevent injury, or guide rehabilitation using the CHAMP Center's advanced Biodex system and software!

Biodex: What It Is

The Biodex Strength Assessment evaluates joint-specific strength and muscular performance using an isokinetic dynamometer. This device measures how muscles generate force and control movement at controlled speeds, providing insight into raw strength, functional movement, and power.

Participants are secured in a specialized chair and push or pull against attachments corresponding to the joint being tested. Torque, power, and strength are recorded at multiple speeds, and both sides of the body are assessed. The test can be customized for joints such as the knee, shoulder, or ankle to support athletic performance, track recovery, or identify imbalances affecting daily movement. Testing typically lasts 20–40 minutes depending on the joints and speeds assessed. Further test preparation can be found on the CHAMP Center Prepare Page.

At the CHAMP Center, we use the Advantage BX™ Software on our Biodex™ system, providing the most up-to-date, reliable, and repeatable data available. This allows us to capture detailed information on joint mechanics, imbalances, and muscle performance, ensuring accurate assessment for performance optimization, rehabilitation, or injury prevention.

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Biodex: Why It's Important

Muscle strength, balance, and joint function are critical for performance, daily activities, and long-term musculoskeletal health. Even small weaknesses or imbalances can lead to compensatory movement patterns, reduced efficiency, or injury. The Biodex Strength Assessment provides objective data to guide targeted interventions.

Biodex testing across multiple speeds allows participants to:
• Low Speeds: Assess maximal strength and control
• Moderate Speeds: Evaluate functional strength used in everyday movements
• High Speeds: Measure power and explosiveness

Understanding performance across these conditions allows participants to:
• Identify weaknesses or side-to-side imbalances
• Develop targeted strength or rehabilitation strategies
• Improve movement efficiency and joint stability
• Support safe return to sport, activity, or work

The Biodex provides precise, actionable information to optimize training, rehabilitation, and injury prevention.

At the CHAMP Center, we can customize the Biodex testing protocol to each individual’s needs.

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Biodex: Who Should Do It

Biodex testing evaluates muscular strength, power, and balance under controlled conditions using isokinetic and isometric resistance. This assessment is valuable for anyone seeking objective, joint-specific insight into strength, symmetry, and neuromuscular performance including:

Team-Sport or Strength Athletes: Optimize strength, power, and force production across multiple velocities, or establish objective pre-season baselines.
Recreational or Endurance Athletes: Assess strength balance, joint integrity, and force production to support efficient movement, reduce injury risk, and improve performance durability across training cycles.
Post-Injury or Surgery: Quantify strength deficits and track rehabilitation progress following ACL reconstruction, rotator cuff repair, or similar procedures.
History of Recurrent Injury or Chronic Pain: Identify muscular imbalances and neuromuscular deficits that may contribute to joint overload or repeated injury.
Longevity or Function-Focused: Support joint health, preserve functional strength, and maintain safe, efficient movement for daily life and long-term independence.
Screening or Baseline Assessment Needs: Establish objective strength, symmetry, and recovery benchmarks for sport, occupational, or return-to-duty demands.

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Biodex: Interpreting Results

Your Biodex results provide a precise assessment of joint-specific strength, muscle balance, and neuromuscular control across controlled movement speeds. By isolating individual muscle groups and quantifying force production under standardized conditions, Biodex testing evaluates not just maximal strength, but how force is produced, controlled, and maintained throughout a joint’s range of motion. This information is critical for optimizing performance, guiding rehabilitation, reducing injury risk, and supporting long-term joint health.

Following testing, CHAMP Center staff analyze torque, work, power, and symmetry data across multiple velocities to build an individualized strength and joint health profile. Results are interpreted in the context of sport demands, injury history, training background, and functional goals.

Key Metrics Include:

Torque Metrics x8
Work Metrics x6
Power Metrics x3
Range of Motion
Muscle Balance, Symmetry, & Deficits
Velocity Specifics

View the other tabs to read more on each metric.

Work Metrics (Muscular Endurance & Fatigue):

Work measures the total torque generated over a repetition set, giving insight into muscular endurance and fatigue resistance. These metrics are particularly relevant for repetitive movements, athletic performance, and rehabilitation.

Metrics:

Max Rep Total Work (ft-lb):
Total work output during the most forceful repetition set, showing peak muscular capacity over time.

Total Work (ft-lb):
Sum of work across all repetitions. Highlights endurance and sustained force production capability.

Work / Body Weight (%):
Normalized work output relative to body size for meaningful comparison across individuals.

Work First Third vs Last Third (ft-lb):
Measures changes in work production from the beginning to the end of a set. A drop indicates fatigue or reduced endurance.

Work Fatigue (%):
Quantifies the percentage decrease in work over repetitions. High fatigue percentages suggest limited muscular endurance or need for targeted conditioning.

Torque Metrics (Strength & Force Production):

Torque represents the rotational force your muscles generate at a joint. Biodex testing measures how strong and efficient these contractions are, helping to detect deficits and asymmetries.

Metrics:

Peak Torque (ft-lb):
The maximum rotational force produced during a single repetition. Higher values indicate greater muscle strength. Large differences between limbs (>10%) may reveal imbalances affecting performance or injury risk.

Average Peak Torque (ft-lb):
The mean of peak torque values across all repetitions. This metric reflects consistency in force production and helps distinguish true strength from variability caused by fatigue or control issues.

Peak Torque / Body Weight (%):
Torque expressed relative to your body weight, allowing fair comparisons between individuals of different sizes. It helps contextualize your strength for your body mass and functional needs.

Torque at 30° (deg):
Force produced at a specific joint angle (often mid-range), useful for identifying weaknesses at positions that are functionally relevant or prone to injury.

Torque at 0.18 sec:
Early-phase torque production, showing how quickly force can be generated. Slow initial torque may indicate neuromuscular inhibition or delayed activation.

Time to Peak Torque (msec):
Measures how long it takes to reach peak torque. Faster times indicate efficient neuromuscular activation and explosive strength.

Angle of Peak Torque (deg):
Joint position where peak torque occurs. Ideal angles align with functional movement patterns; misalignment may indicate compensation or risk for strain.

Coefficient of Variation (CV %):
Shows variability of torque across repetitions. Higher CV indicates inconsistent force production, suggesting fatigue, poor control, or neuromuscular inefficiency.

Power Metrics (Speed & Explosiveness):

Power metrics reflect how efficiently you generate force quickly, critical for athletic performance and high-speed functional movements.

Metrics:

Average Power (W):
Mean power output across repetitions, indicating ability to maintain speed-strength over time.

Acceleration Time (msec):
Time required to reach desired angular velocity, reflecting neuromuscular coordination and explosive capability.

Deceleration Time (msec):
Ability to control and slow movement at the end of the range, which is essential for joint protection and movement efficiency.

Muscle Balance, Symmetry, & Deficits:

These metrics identify asymmetries between limbs or between agonist/antagonist muscle groups, highlighting potential injury risks or training priorities.

Metrics:

Agonist/Antagonist Ratio (%):
Compares the balance between opposing muscles (e.g., quadriceps vs hamstrings). Imbalances may predispose joints to overload or injury.

L/R Limb Comparison:
Evaluates side-to-side differences in strength, work, and power. This metric is useful for post-injury monitoring, identifying natural asymmetries, and guiding corrective training.
- Involved refers to a limb affected by injury or surgery
- Uninvolved refers to a healthy or non-injured limb. For individuals without injury, both limbs are considered uninvolved.

% Deficits: Quantifies the difference between limbs for specific metrics, including:
- Peak Torque (ft-lb)
- Torque at 30° (deg)
- Torque at 0.18 sec
- Max Rep Total Work (ft-lb)
- Total Work (ft-lb)
- Average Power (W)

How to interpret deficits:

>10% difference: May warrant further investigation or corrective training.
>20% difference: Often indicates a significant impairment or underlying neuromuscular issue that should be addressed before returning to high-intensity activity.

Range of Motion (ROM):

Range of Motion (ROM) metrics describe how far a joint moves during testing and the alignment of strength with functional positions. Restricted ROM may indicate stiffness, prior injury, or flexibility limitations and informs corrective mobility work.

Angle of Peak Torque (deg): Shows the specific joint angle at which peak torque occurs.

ROM (deg): How far your joint moves during testing.

How ROM & Angle of Peak Torque work together:

Angle of Peak Torque indicates functional strength within that ROM:
Ideally, peak force occurs in the mid-range of motion, where muscles are most efficient and least vulnerable to injury.

If peak torque occurs near the extreme ends of ROM, it may indicate:
- Limited functional strength in the mid-range
- Compensation patterns
- Potential risk areas for joint overload

By evaluating these together, you get insight into both how far the joint moves and where within that range the muscles are strongest, guiding training, rehab, and injury prevention.

Velocity-Specific Analysis:

Biodex tests at multiple speeds (commonly 60, 180, and 300°/sec), revealing how strength, endurance, and power change with movement velocity.

Common Velocities:

60°/sec: Focused on raw strength and control.
180°/sec: Reflects functional strength relevant for daily activities and moderate-speed movements.
300°/sec: Evaluates high-speed power, coordination, and neuromuscular efficiency.

Why it matters:
Strength may appear sufficient at slow speeds but can break down at faster velocities. Velocity-specific testing ensures your muscles are capable under the full range of functional and sport-specific demands.

At the CHAMP Center, protocol speeds can be tailored to the individual’s goals, such as sport-specific demands, rehab stage, or functional requirements.

How to Use Your Results:

Identify joint-specific strength deficits and asymmetries that may limit performance or increase injury risk
Guide individualized strength training, rehabilitation progressions, or return-to-sport decisions
Monitor recovery and readiness following injury, surgery, or periods of high training load
Optimize strength and power development across velocities relevant to sport or daily function
Support long-term joint health, movement efficiency, and durability
Pair Biodex results with DEXA to understand how lean mass distribution aligns with joint-specific strength findings, Gait Analysis to see how strength and symmetry translate into real-world movement patterns, or other movement assessments to create a comprehensive picture of performance, injury risk, and long-term joint health.