Methods
Study identification and selection
A MEDLINE (National Library of Medicine, Bethesda,
MD, USA) database was used for selection of the
literature (from 1980 to November 2004), and
relevant references from peer-reviewed articles
were retrieved as well. The keywords used in the
literature search were: (1) respiratory muscles and
synonyms; (2) RMT or exercise and synonyms; (3)
spinal cord injury (SCI), paraplegia or quadriplegia
and synonyms. Reference lists of all articles
obtained were considered and additional possible
relevant studies were retrieved. Studies investigating
the effects of RMT [weight resistive, flow
resistive, flow independent (threshold pressure) or
normocapnic hyperpnea] in persons with SCI were
selected based on abstract. Further exclusion
criteria were: (1) not written and available in
English; (2) animal studies; (3) review papers; (4)
studies with training programs that used glossopharyngeal
breathing, abdominal binding, electrostimulation
or functional electrostimulation,
phrenic nerve pacing or general exercise training
(e.g. arm cranking exercise). These criteria were
applied by one reviewer (S.V.H.)