Objective: To assess the reliability of maximal
inspiratory pressure (Pimax) and maximal expiratory
pressure (Pemax) in subjects with multiple sclerosis (MS)
and healthy control subjects by identifying the number of testing
sessions and the number of measurements needed in a single testing
session to obtain consistent, reproducible results.
Design: A descriptive, comparative design with repeated
measures was used.
Setting: Four sets of 10
Pimax and 10 Pemax measurements were obtained
over a 4-week period from MS subjects in their homes. The same
measurements were obtained from healthy control subjects in a private
Subjects: Seventy-two MS patients and 61
healthy control subjects participated in the study.
Measurement: Pimax and Pemax values
were obtained by using previously published methods.
Results: Mean Pemax and Pimax
values for MS patients differed over the first three of the four
testing sessions. By contrast, mean Pemax and
Pimax values for healthy control subjects differed only
when the first session values were compared with values from the last
three sessions. For MS patients, Pemax and
Pimax increased between the first and 10th trial during the
first testing session, but not during the subsequent three
Conclusions: The results of this study
suggest that several practice sessions should be provided in order to
obtain reliable Pemax and Pimax values in
persons with MS. At least one practice session should be provided for
healthy control subjects before identifying a