There are no data available as to whether training with eccentric contractions are more effective than concentric contractions for producing skeletal muscle fiber hypertrophy. To better understand the effects of training with different contraction types two related studies were performed.
In the first study a device which is frequently used by clinicians for concentric and eccentric exercise, the Kin-ComR, was tested for accuracy and reliability. The measurements obtained from the force, angle, and speed transducers of this device were found to be accurate and reliable between days.
The purpose of the second study was to determine if there was a difference in the percent change of fiber area in the vastus lateralis muscle as a result of concentric and eccentric exercise at equal power levels. Twenty normal subjects were randomly assigned to two groups. Both groups exercised three times per week for four weeks on the Kin-Com dynamometer. One group performed concentric contractions of their right quadriceps femoris muscle at an intensity of 90% of their maximal concentric power through a range of 75° of knee extension. The other group performed eccentric contractions at the same relative power level. Needle muscle biopsies were obtained from the vastus lateralis muscle before and after the exercise program. Muscle fiber type differentiation was performed using a myosin adenosine triphosphatase stain at an alkaline preincubation. The percent change in fiber area was determined for each fiber type for each subject and a one-way ANOVA was used to analyze the data. Our results showed that the type II fibers of the concentric group exhibited a greater percent increase in area as compared to the eccentric group. The percent change in isometric torque was determined for each subject and a one-way ANOVA was performed on the data. The results showed that the concentric group increased maximal isometric torque production more than the eccentric group. Our results indicate that when exercising at the same relative power level a subject performing concentric contractions will 1) show greater muscle hypertrophy and, 2) improve in isometric torque production more than a subject training with eccentric contractions.
| Identifer | oai:union.ndltd.org:vcu.edu/oai:scholarscompass.vcu.edu:etd-6312 |
| Date | 01 January 1991 |
| Creators | Mayhew, Thomas Philip |
| Publisher | VCU Scholars Compass |
| Source Sets | Virginia Commonwealth University |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | Theses and Dissertations |
| Rights | © The Author |
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