Interpretation of Isokinetic Tests

1
Interpretation of Isokinetic Tests
2
Concepts

• Introduction
• Principle of isokinetics
• Benefits of training through isokinetic exercise
• Basic terminology
• Reading test results
• Curve analysis

3
Introduction

• Subjective/objective
• Criteria-based protocols
• Goals with reproducible data
• Biodex advantage!

4
Principles of isokinetics

• Preset fixed speed
• Accommodating resistance
• Resistance effort
• Torque measured throughout ROM
• Muscle loaded throughout ROM
• 30 degree overflow
• Strength
• physiological

5
Functional Test Speeds

• Walking 233/s
• Running 1000/s 1200
• Ankle during running 540/s
• Train test at fast speeds

6
Benefits of training

• Time rate of tension development (TRTD)
• Upslope of the curve
• Decreased reciprocal innervation time (RIT)
• Time between end of agonist and beginning of
  antagonist
• Strengthen musculotendinous junction
• Reduces risk of strains

7
Basic Terminology/Interpretation

• Peak torque
• Absolute strength value (1 RM)
• Work
• Functional value of muscle performance
• Torque over distance
• Power
• How effective the muscle can perform work over
  time

8
Reading test results

• Is the test reliable and valid?
• Coefficient of variance
• Large values?
• Acceptable CVs (large/small muscle groups)

9
Reading test results

• Percent deficit
• Acceptable vs unacceptable
• Negative value?
• Considerations for unilateral athletes?

10
Reading test results

• Peak torque
• Difficult to assess if used alone
• Peak torque/body weight
• of torque produced to body weight
• Normative goals - see chart

11
Reading test results

• Max rep total work
• Better indicator of neuromuscular function
• Muscle must remain recruited during entire range
• Should occur within first few reps of test
• Work first 1/3..work last 1/3
• Should be more work in first 1/3
• Look for consistency
• Effort

12
Reading test results

• Work fatigue
• Ratio between first 1/3 and last 1/3
• Should decrease with progress
• Acceleration time
• Time to reach isokinetic speed
• Deceleration time
• From isokinetic speed to zero
• Eccentric control towards end of ROM

13
Curve analysis

• 4 regions of the curve
• Time rate of torque development (TRTD)

14
Curve analysis

• Force Decay Rate

T
FDR
FDR
ROM Uninvolved side

• ROM
• Involved side

15
Curve analysis

• Reciprocal innervation time (V vs U)

16
Injury/condition curves
17
Chondromalacia patella
Q
Q
H
H
18
Plica syndrome
19
Patellar subluxation
20
ACL Deficiency
21
Summary Reports

• Absolute/relative
• Bilateral comparisons
• Unilateral comparisons

Speed Ratio
60/s 60 - 69
180/s 70 - 79
300/s 80 - 95
450/s 95 - 100
22
TBW Ratio

• General joint integrity

Males Males Females Females
60/s 110-115 60/s 85 - 95
180/s 65 - 75 180/s 55 - 65
300/s 45 - 55 300/s 35 - 45
450/s 35 - 40 450/s 25 - 30
23
Summary

• Correlate to clinical exam
• Use pre-established criteria
• Valid/reproducible or throw out
• Documents muscular performance only