## 4 Discussion  
Overall, the results of this study did not reveal that any one soft-tissue modality significantly differs from another. Static stretching, foam rolling, and percussion massage did not alter the cross-sectional area, echo intensity, pennation angle, fascicle length, or muscle thickness. The results agree with much of the literature in that none of the three modalities improve performance as we did not observe any significant changes in peak torque or muscle activation. The only significant difference that was observed was in the strength output and muscle size of the male participants. The males were able to generate more force and had a larger muscle mass. This was known and controlled in the study [46]; however, it is of note that regardless of size and strength, there was no significant difference in the use of all three modalities between sexes. For static stretching, there were no statistically significant differences on all performance metrics. These results back the findings of much of the current literature in that static stretching has no effect on improving performance [4; 12; 13; 15; 16; 17] or a slight decrease in performance of \(<\)5% [12]. [PERSON] et al. [20] reported an increase in ROM of 4.3\({}^{\circ}\), corresponding to a 2\({}^{\circ}\) increase in pennation angle. Changes in fascicle length or pennation angles were not observed in our study. This is similar to the results reported by [PERSON] et al. [19]. Static stretching has been shown to decrease stiffness [13], while echo intensity is related  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline  & & **Control** & & \multicolumn{2}{c}{**Stretch**} & \multicolumn{2}{c}{**Foam Roll**} & \multicolumn{2}{c}{**Percussion Massage**} \\
**Cross-Sectional Area** & Pre & Post & Pre & Post & Pre & Post & Pre & Post \\ (**cm\({}^{2}\)**) & & & & & & & & \\ \hline Male * & \(16.8\pm 4.0\) & \(18.5\pm 5.6\) & \(16.7\pm 4.4\) & \(16.7\pm 4.3\) & \(18.9\pm 4.4\) & \(18.6\pm 5.2\) & \(17.7\pm 4.3\) & \(18.5\pm 6.0\) \\ Female & \(10.5\pm 3.1\) & \(11.2\pm 2.5\) & \(13.7\pm 2.8\) & \(14.9\pm 3.3\) & \(12.5\pm 3.5\) & \(13.2\pm 3.2\) & \(11.0\pm 2.4\) & \(10.8\pm 2.0\) \\
**Echo Intensity (a.u. )** & & & & & & & & \\ Male & \(48.2\pm 18.7\) & \(52.7\pm 13.5\) & \(60.8\pm 13.7\) & \(61.5\pm 10.4\) & \(61.8\pm 13.7\) & \(56.0\pm 14.7\) & \(57.6\pm 15.4\) & \(60.4\pm 14.9\) \\ Female & \(55.9\pm 11.7\) & \(59.5\pm 10.0\) & \(58.7\pm 5.7\) & \(57.8\pm 6.8\) & \(66.1\pm 11.6\) & \(65.0\pm 7.6\) & \(62.5\pm 9.7\) & \(58.0\pm 10.1\) \\
**Pennation Angle (*)** & & & & & & & & \\ Male * & \(15.3\pm 4.8\) & \(16.1\pm 3.3\) & \(14.3\pm 3.8\) & \(14.0\pm 4.3\) & \(16.0\pm 3.7\) & \(16.1\pm 4.2\) & \(15.0\pm 3.6\) & \(14.2\pm 2.4\) \\ Female & \(13.5\pm 3.6\) & \(14.7\pm 3.3\) & \(11.7\pm 3.2\) & \(12.1\pm 3.8\) & \(14.5\pm 3.5\) & \(14.8\pm 2.8\) & \(12.7\pm 2.4\) & \(12.9\pm 2.7\) \\
**Fascicle Length (cm)** & & & & & & & & \\ Male * & \(10.7\pm 1.6\) & \(10.7\pm 1.3\) & \(11.2\pm 2.4\) & \(11.5\pm 2.8\) & \(11.0\pm 1.7\) & \(10.5\pm 2.1\) & \(10.0\pm 1.6\) & \(10.4\pm 2.3\) \\ Female & \(9.8\pm 0.9\) & \(9.7\pm 1.3\) & \(10.3\pm 1.5\) & \(10.5\pm 1.7\) & \(9.7\pm 0.9\) & \(9.9\pm 1.2\) & \(9.1\pm 1.3\) & \(9.5\pm 1.3\) \\
**Muscle Thickness (cm)** & & & & & & & & \\ Male * & \(2.5\pm 0.5\) & \(2.6\pm 0.4\) & \(2.2\pm 0.5\) & \(2.3\pm 0.5\) & \(2.5\pm 0.4\) & \(2.3\pm 0.5\) & \(2.3\pm 0.3\) & \(2.2\pm 0.4\) \\ Female & \(2.1\pm 0.5\) & \(2.2\pm 0.4\) & \(2.0\pm 0.5\) & \(2.0\pm 0.5\) & \(2.0\pm 0.4\) & \(2.0\pm 0.3\) & \(2.0\pm 0 to changes in elongation and stiffness [25] of the muscle. We, however, did not observe any differences between pre- and post-stretching echo intensity values. Even though we did not measure stiffness or ROM, we did not see any changes in muscle characteristics that would indicate that acute stretching does not alter any muscle morphology. If stiffness were to decrease, we would have seen a decrease in echo intensity, based off the work of [PERSON] et al. [25].