The effects of strength training in patients with selected neuromuscular disorders.
Five subjects with spinal muscular atrophy, limb-girdle or facioscapulohumeral muscular dystrophy, were studied. Measurements pre- and post-training included: maximum isometric, dynamic and isokinetic strength, in single-arm curl and double-leg press exercises; contractile properties of the elbow flexors; computerized tomography of the upper arms and thighs; muscle biopsies from the biceps brachii muscle of each arm in three subjects. Dynamic weight training was performed 3 times per week for 9 wk; exercises comprised unilateral arm curls (the contralateral arm acted as a control), and bilateral leg press. Strength increases in the trained arm were between 19 and 34%, and from -14 to +25% in the control arm; leg strength increased from 11 to 50%. Moreover, the pretraining maximum load could be lifted from 3 to 48 times in the trained limbs, and from 1 to 13 times in an untrained limb before fatigue. Contractile properties of the elbow flexors were unchanged with training, but pre-intervention, three subjects demonstrated incomplete motor unit activation. Most of the gains in strength were apparently due to a neural adaptation, rather than muscle hypertrophy. The tomograms and biopsy samples were inadequate to determine muscle, or muscle fiber areas with confidence; they did indicate however, no additional overt muscle structural damage. Strength training may be a potentially useful therapeutic option in the management of selected neuromuscular disorders.
McCartney
N
N
Department of Physical Education, McMaster University, Hamilton, Ontario, Canada.
Moroz
D
D
Garner
S H
SH
McComas
A J
AJ
D000328:Adult; D005081:Exercise Therapy / Q000379:methods*; D005260:Female; D006801:Humans; D007537:Isometric Contraction; D008297:Male; D008875:Middle Aged; D009046:Motor Neurons / Q000502:physiology; D009132:Muscles / Q000000981:diagnostic imaging / Q000503:physiopathology; D009134:Muscular Atrophy, Spinal / Q000503:physiopathology / Q000534:rehabilitation*; D009136:Muscular Dystrophies / Q000503:physiopathology / Q000534:rehabilitation*; D010807:Physical Endurance; D014057:Tomography, X-Ray Computed; D014891:Weight Lifting