The Influence of Velocity-Specific Resistance Training on the In Vivo Torque-Velocity Relationship and the Cross-Sectional Area of Quadriceps Femoris

A two-arm, prospective, randomized, controlled trial study was conducted to investigate the effects of movement velocity during progressive resistance training (PRT) on the size and contractile properties of individual fibers from human vastus lateralis muscles. The effects of age and sex were examined by a design that included 63 subjects organized into four groups: young (20–30 yr) men and women, and older (65–80 yr) men and women. In each group, one-half of the subjects underwent a traditional PRT protocol that involved shortening contractions at low velocities against high loads, while the other half performed a modified PRT protocol that involved contractions at 3.5 times higher velocity against reduced loads. Muscles were sampled by needle biopsy before and after the 14-wk PRT program, and functional tests were performed on permeabilized individual fiber segments isolated from the biopsies. We tested the hypothesis that, compared with low-velocity PRT, high-velocity PRT results in a greater increase in the cross-sectional area, force, and power of type 2 fibers. Both types of PRT increased the cross-sectional area, force, and power of type 2 fibers by 8–12%, independent of the sex or age of the subject. Contrary to our hypothesis, the velocity at which the PRT was performed did not affect the fiber-level outcomes substantially. We conclude that, compared with low-velocity PRT, resistance training performed at velocities up to 3.5 times higher against reduced loads is equally effective for eliciting an adaptive response in type 2 fibers from human skeletal muscle.

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Effects of Unilateral Concentric-Only Dynamic Constant External Resistance Training on Quadriceps Femoris Cross-Sectional Area

The Journal of Strength and Conditioning Research ◽

10.1519/00124278-199808000-00011 ◽

1998 ◽

Vol 12 (3) ◽

pp. 185-191 ◽

Cited By ~ 1

Author(s):

Dona J. Housh ◽

Terry J. Housh ◽

Joseph P. Weir ◽

Loree L. Weir ◽

Tammy K. Evetovich ◽

...

Keyword(s):

Resistance Training ◽

Quadriceps Femoris ◽

Cross Sectional Area ◽

Sectional Area ◽

External Resistance ◽

Cross Sectional

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Comparison of Endolymph Cross-Sectional Area Measured Histologically with that Measured in Vivo with an Ionic Volume Marker

Annals of Otology Rhinology & Laryngology ◽

10.1177/000348949510401111 ◽

1995 ◽

Vol 104 (11) ◽

pp. 886-894 ◽

Cited By ~ 9

Author(s):

Alec N. Salt ◽

John E. Demott ◽

Robert S. Kimura

Keyword(s):

Injection Site ◽

Cross Sectional Area ◽

Endolymphatic Sac ◽

Sectional Area ◽

Cross Sectional ◽

Constant Rate ◽

Two Measures ◽

The Cross ◽

Ionic Volume

In order to establish how endolymph volume is regulated, it is essential to be able to measure endolymph volume or cross-sectional area in vivo. We have developed methods to accomplish this by injecting the volume marker ion hexafluoroarsenate (AsF6) into endolymph by iontophoresis. For an injection at a constant rate, the endolymph concentration is inversely dependent on the cross-sectional area of the scala into which injection occurred. Marker concentrations were monitored by inserting ion-selective microelectrodes into endolymph near the injection site. In a previous study we quantified the degree of hydrops in animals following ablation of the endolymphatic sac. In the present study we validated the technique by comparing the endolymphatic cross-sectional area measured in vivo with AsF6 with that measured by established histologic procedures. The correlation between the two measures was good, with a coefficient of .903, although the area measured histologically was a little lower than that measured in vivo.

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