Strengthening hip flexors to improve walking distance in people with CMT

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(Poster session at Antwerp consortium July 2009)

Strengthening hip flexors to improve walking distance in people with

Charcot-Marie-Tooth Disease.

A. Pollard1 G.M. Ramdharry2, J.F. Marsden3 and M.M. Reilly4

1Department of Molecular Pathogenesis, Institute of Neurology, Queen Square,

London WClN 3BG, UK; 2St 's School of Physiotherapy Kingston University

Cranmer Terrace SWl7 ORE, UK; 'School of Health

Professions, University of Plymouth, Deniford Road PL6 8BH,UK; 4MRC Centre for

Neuromuscular Diseases, DepaItment of Molecular Pathogenesis, Institute of

Neurology, Queen Square, London WClN 3BG, UK

People with Charcot-Marie-Tooth disease (CMT) present with distal weakness,

wasting and sensory loss resulting from degeneration of the long peripheral

nerves. In normal gait the hip flexor and plantarflexor muscles work in synergy

to accelerate the leg forwards into the swing phase of gait. However, walking

studies of people with CMT have revealed that they utilise a proximal adaptive

gait strategy to compensate for distal impairments. More specifically, it has

been suggested that when the plantarflexor muscles are weakened in

people with CMT, the hip flexor muscles initiate swing phase in isolation.

The consequences of this compensatory strategy were tested when people with CMT

(n=18) were walking for long distances on a treadmill. It was found that the hip

flexor compensatory strategy

fatigues with prolonged walking and may limit walking endurance.

We hypothesise that strengthening the hip flexor muscles with a home training

programme will increase walking duration as people with CMT will be able to

compensate for longer.

A single-blinded cross-over study will investigate the efficacy of the 16-week

home programme for 32 people with all types of CMT.

We have devised a training schedule of resistance exercises through a range of

45° at 40% of maximum voluntary contraction. The resistance will be progressed

as the subject increases in strength. A protocol of impairment and activity

measures has been devised to test the

hypothesis. A custom made fixed myometry set up will be used to measure hip

flexor strength and walking endurance will be measured using the six minute

timed walk with additional measures of heart rate and perceived exertion.

Additional measures of gait speed,

fatigue, disease impact and general activity will also be used to assess the

response to training.

The potential impact of the study will be to inform physiotherapists of

efficacious strengthening intervention for the specific functional problem of

walking endurance in people with CMT.

References

I. Don R, Senao M, Vinci P, Ranavolo A, Cacchio A, Ioppolo F, Paoloni M,

Procaccianti R,

Frascarelli F, De Santis P, Pierelli F, Frascarelli M, Santilli V. Foot drop and

plantar

flexion failure determine different gait strategies in Charcot-Marie-Tooth

patients.. Clinical

Biomechanics 2007; 22:905-916

2 Ramdharry G, Day B, Reilly M, and Marsden J. Hip Flexor Fatigue limits walking

in

Charcot-Marie-Tooth Disease Muscle and Nerve (article in press