THE INFLUENCE OF LENGTH CHANGE SPEED AND DIRECTION ON DYNAMIC FUNCTION POTENTIATION IN FAST MOUSE MUSCLE

The purpose of this study was to test the hypothesis that the potentiation of dynamic function was dependent upon both length change speed and direction. Mouse EDL was cycled in vitro (250 C) about optimal length (Lo) with constant peak strain (± 2.5% Lo) at 1.5,3.3 and 6.9 Hz before and after a conditioning stimulus. A single pulse was applied during shortening or lengthening and peak dynamic (concentric or eccentric) forces were assessed at Lo. Stimulation increased peak concentric force at all frequencies (range: 19±1 to 30 ± 2%) but this increase was proportional to shortening speed, as were the related changes to concentric work/power (range: -15 ± 1 to 39 ± 1 %). In contrast, stimulation did not increase eccentric force, work or power at any frequency. Thus, results reveal a unique hysteresis like effect for the potentiation of dynamic output wherein concentric and eccentric forces increase and decrease, respectively, with work cycle frequency.

Name thesis:degree_name

M.Sc. Applied Health Sciences

Level thesis:degree_level

Masters

Discipline thesis:degree_discipline

Faculty of Applied Health Sciences

Department dc:contributor.department

Applied Health Sciences Program

Grantor

Brock University

Year dc:date.issued

2013

Author dc:creator

• Caterini, Daniel

• work cycle frequency
• eccentric contractions
• speed and direction
• muscles

Handle dc:identifier.uri

http://hdl.handle.net/10464/4234

OAI identifier oai:identifier

oai:brocku.scholaris.ca:10464/4234