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This Article Full Text Full Text (PDF) All Versions of this Article: 89/5/583    most recent expphysiol.2004.027680v1 Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Gallo, M. Articles by Putman, C. T. Search for Related Content PubMed PubMed Citation Articles by Gallo, M. Articles by Putman, C. T. Related Collections Muscle

¹ Exercise Biochemistry Laboratory, Faculty of Physical Education and Recreation² Division of Physical Medicine and Rehabilitation³ Centre for Neuroscience, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada T6G 2H9

The present study investigated the absolute reliability (R_Ab) of isometric measures of time-to-peak tension (TTP), half-rise time (RT), half-fall time (FT), twitch force (TW_f) tetanic force (TET_f) and the sag ratio as applied to the slow soleus (SOL) and the fast-twitch extensor digitorum longus (EDL) and medial gastrocnemius (MG) muscles of the rat hindlimb. In addition, the relationship of each individual isometric measure was examined with regard to the pattern of myosin heavy chain (MHC) isoform expression. Measures of TTP, RT, FT and sag ratio were negatively correlated with MHCIId(x) and MHCIIb (P < 0.0001), and positively correlated with MHCI (P < 0.0001). TW_f and TET_f were negatively correlated with MHCI content (P < 0.0001) and positively with MHCIId(x) (P < 0.0001) and MHCIIb (P < 0.001). Comparisons of isometric measures using a paired Student's t test revealed that they were not different between the right and left legs; all measures displayed high correlations between the left and right legs (r= 0.71–0.85, P < 0.0001). In contrast to standard tests of statistical significance, these functional measures exhibited a considerable range of R_Ab when individual muscles were studied in only one hindlimb. When averaged across all muscles, however, the FT, RT, TW_f and TTP measures possessed high overall reliability; measures of TET_f and sag ratio were moderately reliable. The results of this study show that the isometric measures studied possess significant predictive value with regard to MHC isoform content; the left and right legs are interchangeable but display a considerable range of reliability when only one hindlimb is studied.

(Received 14 March 2004; accepted after revision 10 June 2004; first published online 15 July 2004)
Corresponding author C. T. Putman: E-417 Van Vliet Centre, University of Alberta, Edmonton, Alberta, Canada, T6G 2H9. Email: tputman{at}ualberta.ca

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