Muscle architecture adaptations to knee extensor eccentric training: rectus femoris vs. vastus lateralis

Muscle architecture adaptations to knee extensor eccentric training: rectus femoris vs. vastus lateralis

 Article Summary

The research article “Muscle architecture adaptations to knee extensor eccentric training: rectus femoris vs. vastus lateralis” written by Baroni, Geremia, Pe, Franke, Karamanidis, and  Vaz and published in the journal of Muscle and Nerve explores the impact of eccentric training on the rectus femoris (RF) and vastus lateralis (VL). The article is published in the Journal of  Muscle and Nerve volume 48 and pages 498-506, released in October 2013. The primary objective of Baroni et al.’s (2013) article was to determine the impact of eccentric training on the rectus femoris (RF) and vastus lateralis (VL). Eccentric training is conducted by contracting the muscle while lengthening it with the goal of changing its structure.

The primary objective/aim of Baroni et al.’s (2013) research study was to assess and compare the effect of a twelve-week eccentric training program in twenty volunteer subjects with a critical focus on the fascicular geometry of rectus femoris (RF) and vastus lateralis (VL). The choice of RF and VL was based on the difference in their characteristics, as the researchers wanted to determine differences in outcomes. The study hypothesized that both pennation angle and fascicle length of RF and VL would increase after the exposure to the eccentric resistance training due to muscle damage. The study sought to answer three research questions which motivated the study. The first question was to explain the conflicting results related to the pennation angle and fascicle length as reported in previous studies conducted on animals. The second question was the lack of evidence on the time-course of the changes occurring in the RF and VL during the eccentric training. The final problem was to extend the eccentric exercise to humans as prior studies had not explored the existence of variations in muscles in humans.

Baroni et al. (2013) conducted a longitudinal clinical trial to meet the objective of their study. Twenty volunteer male university students were exposed to a twelve-week knee extensor program at the interval of four weeks. During the training period, the subjects were studied using the ultrasonography system to determine muscle thickness, pennation, and fascicle length of the RF and VL which were centers of observation in the study. Baroni et al. (2013) conducted their investigation according to the requirements form the Declaration of Helsinki and obtained ethical clearance from the institutional in research committee.

In the analysis of the recordings, the researchers conducted a statistical analysis by computing the mean of the readings recorded in the three scans from the ultrasonography. The mean was calculated based on the recordings obtained from the muscle thickness, pennation, and fascicle length. The results from the study indicated a high test-retest reliability in the testing. Other significant findings from the study included a minimal change in time for the transition to occur in the RF and VL changes. The tabulated and graphed results indicate a substantial change as shown on page 502 of Baroni et al. (2013).

In the discussion section, the researchers explain that a four-week eccentric resistance training was sufficient for significant changes, but they had to extend it to twelve weeks at an interval of four weeks for reliability. Baroni et al. (2013) conclude th

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