AUTHORS: E.M. Beckman (1), Y.C. Vanlandewijck (2); M.J. Connick (1); S.M.

Tweedy (1).

AFFILIATIONS: (1) University of Queensland, School of Human Movement

Studies, Queensland, Australia; (2) Catholic University Leuven, Department

Rehabilitation Sciences, Leuven, Belgium

Evaluating the validity of lower limb muscle

strength tests for classification of runners

with ataxia, athetosis and hypertonia

IPC Athletics Classification System for Physical

Impairments

Purpose of classification –

To minimize the impact of impairment on the

outcome of competition

Classify athletes based on how much

impairment impacts on performance

Background – Classification in Paralympic sport

• Evidence-based classification mandated by IPC – empirical evidence is

required

•IPC Concept map – Athletics classification (Tweedy & Vanlandewijck, 2011)

STRENGTH OF

ASSOCIATION

Coordination

Strength

Range of Movement

(active and passive)

Wheelchair – sprint

performance

Running – sprint performance

Standing Throw performance

Seated throw performance

Tests of Impairment Tests of Performance

Aim

Evaluate the validity of lower limb muscle strength tests for

classification of runners with hypertonia, ataxia, and athetosis.

1. Determine whether AWD are significantly different from

ND athletes on tests of strength

2. Determine the strength of association between tests of

strength and performance in AWD

3. Determine the strength of association between tests of

strength and performance in ND

Methods - Participants

Athletes with disabilities

• n = 13 male athletes: clinically diagnosed hypertonia, ataxia, athetosis

• Competitive runners

• Mean age 25.89 (± 10.37) years

Non-disabled athletes

• n = 28 male athletes

• regularly active in competitive sport

• Mean age 23.1 (± 4.1) years

Methods – Strength tests

Isometric, slow build up of force, standardised positions (measured in Newtons)

Leg flexion Leg extension Plantarflexion

Methods – Performance tests

Acceleration: 0-15m

(seconds)

Top Speed: 30-60m

(seconds)

Statistical Analysis

1. Determine whether AWD were significantly different from ND

athletes on tests of strength

Independent t-test

2. Determine the strength of association between strength

measures and performance in AWD

Pearson’s Correlations

3. Determine the strength of association between strength

measures and performance in ND

Pearson’s Correlations

Results

• AWD significantly slower compared to ND

• AWD significantly weaker in most affected side

compared to ND

• Low to Moderate correlations between

strength and top speed, and low correlations

between strength and acceleration

Difference between AWD and ND ?

AWD Mean (SD)

ND mean(SD)

Top speed (secs)

4.31(0.64)

3.76** (0.27)

Acceleration (secs)

3.18(0.33)

2.76**(0.19)

AWD Mean (SD)

ND mean(SD)

Flexion more affected side

176.46(68.82)

253.48**(83.82)

Flexion less affected side244.98(65.87)

242.99(76.73)

Extension more affected side

992.72(337.37)

1660.64**(363.60)

Extension less affected side

1398.86(234.30)

1663.84 (426.63)

Plantarflexion more affected side

823.54(266.58)

1508.45**(309.31)

Plantarflexion less affected side

1071.98(264.37)

1457.19**(280.21)

Pearson’s Correlations: strength vs running

performanceTopspeed

AWDAcceleration

AWDTopspeed

NDAcceleration

ND

Flexion more affected side

Pearson Correlation -.131 .174 -.493** -.481**

Sig. (2-tailed) .686 .589 .008 .009

Flexion less affected side

Pearson Correlation -.237 .077 -.331 -.239

Sig. (2-tailed) .459 .813 .085 .221

Extension more affected side

Pearson Correlation -.148 .218 -.089 -.172

Sig. (2-tailed) .646 .496 .653 .382

Extension less affected side

Pearson Correlation -.291 .085 -.062 -.111

Sig. (2-tailed) .359 .793 .756 .574

Plantarflexion more affected side

Pearson Correlation -.318 .133 -.086 -.014

Sig. (2-tailed) .290 .665 .664 .944

Plantarflexion less affected side

Pearson Correlation -.427 -.061 -.111 -.098

Sig. (2-tailed) .146 .843 .573 .621

Discussion

Correlations strength vs performance

R² = 0.119

R² = 0.0124

3.00

3.50

4.00

4.50

5.00

5.50

6.00

0.00 500.00 1000.00 1500.00 2000.00 2500.00

T

o

p

S

p

e

e

d

Plantarflex strength

AWD

ND

Linear (AWD)

Linear (ND)

Discussion

• Low associations between strength and

performance may be related to slow isometric

force build up

• Plantarflexion on less affected side potentially

the best predictor of performance (more affected

side important too)

• Stronger trend in top speed: is acceleration

related to coordination or range of motion?

Conclusions

• Early indications that these tests are potentially

valid for use in classification in athletes with

ataxia, athetosis, hypertonia

• More athletes are required to demonstrate the

relative weighting of each test to performance