Document Type

Article

Language

eng

Format of Original

8 p.

Publication Date

5-1987

Publisher

American Physiological Society

Source Publication

Journal of Applied Physiology

Source ISSN

0021-8987

Original Item ID

DOI: 10.1152/jappl.1987.62.5.2075

Abstract

This study examined the effect of high- (75 Hz, 1 min) and low- (5 Hz, 1.5 min) frequency stimulation on contractile and biochemical properties of the diaphragm. Tension was reduced to 21 ± 1 and 54 ± 2% (SE) of the initial value after high- and low-frequency stimulation, respectively. After 0, 0.25, 1, and 2 min of recovery from high-frequency stimulation, 5 Hz elicited more force (expressed as % of initial tension) than 75-Hz stimulation. Time 0 recovery values were 21 ± 1 and 78 ± 6% of the initial force for 75- and 5-Hz stimulation, respectively. By 1 min of recovery, force elicited by 5-Hz stimulation had returned to the prefatigue value. In contrast, force production with 75-Hz stimulation did not full recover until 10–15 min. After fatigue produced by low-frequency stimulation, force production with 5-Hz stimulation was reduced to 54 ± 2% of the initial tension, a value significantly lower than the 71 ± 2% of initial force elicited by 75-Hz stimulation. Force production with 5-Hz stimulation increased rapidly in the first 15 s of recovery (54 ± 2% at 0 and 70 ± 2% at 15 s) and by 5 min was significantly greater than the force elicited by 75-Hz stimulation (100 ±3 vs. 93 ± 1%). As before, force production at 75-Hz stimulation did not fully recover until 10–15 min. Both fatigue protocols produced a significant prolongation in isometric twitch contraction and one-half relaxation times. Creatine phosphate (CP) concentration was reduced and muscle lactate increased by both fatigue protocols.(ABSTRACT TRUNCATED AT 250 WORDS)

Comments

Published version. Journal of Applied Physiology, Vol. 62, No. 5 (May 1987): 2075-2082. DOI. © 1987 American Physiological Society. Used with permission.

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