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Isokinetic Muscle Testing

Isokinetic muscle testing is a type of strength testing that evaluates muscle performance under controlled conditions using specialised equipment. It’s commonly used in sports medicine, rehabilitation, and research to assess strength, endurance, and muscle balance. To date, it is still the most advanced strength testing equipment in the world.

What Is Isokinetic?

• “Iso” = same, “kinetic” = motion → So, isokinetic means constant speed.

• During isokinetic testing, the machine keeps the movement speed constant regardless of how much force the person applies.

• The resistance adjusts in real time: the harder you push, the more resistance the machine gives, but the speed stays constant.

• In doing so therapists are able to measure the amount of force produced against the machine at a constant speed.

How It Works

The patient performs movements like knee extension/flexion, shoulder rotation, or elbow flexion using a dynamometer (e.g. Biodex, Cybex, Humac).

The machine records data such as:
○ Peak torque (strength)
○ Work and power output
○ Muscle endurance
○ Agonist/antagonist ratio (e.g. hamstring to quadriceps)

Example: Knee Testing

  • The athlete performs knee extensions and flexions at different speeds (e.g. 60°/sec, 180°/sec).

     

  • The machine plots a torque curve and gives data about:
    • Maximum force production
    • Muscle fatigue over repeated reps
    • Balance between quadriceps and hamstrings
    • % of force production to body weight

Common Applications

  • Rehabilitation: To track recovery after injury or surgery (like ACL reconstruction, knee replacements, rotator cuff repair etc).

  • Injury Prevention: Identify muscle imbalances that might lead to injury and being able to correct these before injury occurs.

  • Athletic Training: Assess strength development or readiness to return to sport. Also measures athlete’s strength deficits to gauge injury progress.

  • Research: Analyze muscle function in clinical or performance studies.

Key Benefits

Isokinetic testing offers several benefits in clinical, athletic, and rehabilitation settings. It measures muscle strength, endurance, and power by controlling the speed of movement during exercise. 

  • Provides accurate, reproducible measurements of muscle strength and torque.

  • Useful for baseline testing, progress monitoring, and return-to-play decisions.

  • Allows for eccentric testing and neuromuscular rehabilitation as opposed to only concentric evaluations.
  • The speed of joint movement is kept constant, allowing for safe testing even in injured individuals.

  • Reduces the risk of compensatory movements and further injury.
  • Identifies asymmetries between:
    o Agonist vs. antagonist muscles (e.g. quadriceps vs. hamstrings)
    o Left vs. right limbs
  • Crucial for injury prevention and targeted rehabilitation.
  • Tracks rehabilitation progress and functional recovery over time.

  • Adjusts exercise intensity based on real-time performance.
  • Helps develop sport-specific training by identifying deficits in power or endurance.

  • Provides data to optimize training and reduce injury risk.
  • Appropriate for athletes, elderly individuals, and patients post-surgery or with chronic conditions.

  • Resistance adapts to the user’s force output, reducing strain on joints and soft tissues.
  • Real-time visual and auditory feedback improves user engagement and motivation.

  • Encourages maximal effort during testing and training.

Bookings

Phone
Stuart McDade
076 311 2344
Email
stumcdade@gmail.com
Website
sbmbiokinetics.co.za
Location
Netcare Waterfall City Hospital
Waterfall Sports Orthopaedic Surgery
South Block
Third Floor
Room 301
Location
Premier Health Centre
13 Mackay Avenue
Blairgowrie


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