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--- sift:tutorials:openbiomechanics_project:analysis_of_shoulder_angular_velocity_baseball_pitching [2024/10/18 22:19] – Changed C-Motion to HAS-Motion. wikisysop
+++ sift:tutorials:openbiomechanics_project:analysis_of_shoulder_angular_velocity_baseball_pitching [2024/10/23 17:58] (current) – Removed commentary interpreting the shape of non-significant SPM result. wikisysop
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 Shoulder angular velocity is a key metric in evaluating the effectiveness of a baseball pitch. While pitch performance is often linked to shoulder angular velocity, the complex nature of shoulder biomechanics presents challenges in standard analysis. In this study, we focus on the Z-axis (internal-external rotation) of shoulder angular velocity using a Y-X-Z Cardan sequence, particularly analyzing elite-level college pitchers and average collegiate pitchers.
-We compare the top 10 pitchers, defined by their pitch speed, to the general college pitcher population. Contrary to initial expectations, the findings reveal that the mean shoulder angular velocity in the Z-direction for elite pitchers is lower than that of average pitchers. However, elite pitchers exhibit significantly higher variability in this metric. Statistical Parametric Mapping (SPM) analysis further suggests that the most substantial differences occur early in the pitching motion when the arm is at its maximum height. This study provides insights into the complexity of shoulder motion in elite pitchers, highlighting that factors beyond shoulder angular velocity may contribute to superior pitch performance.
+We compare the top 10 pitchers, defined by their pitch speed, to the general college pitcher population. Contrary to our initial expectations, the findings reveal that there are no significant differences between the Elite Level Pitchers and the average collegiate pitching population in terms of shoulder angular velocity as found through an SPM analysis. This study provides insights into the complexity of shoulder motion in elite pitchers, highlighting that factors beyond shoulder angular velocity may contribute to superior pitch performance.
 This investigation shows the utilization of Sift as a powerful tool that allows for efficient data processing and comparison to analyze motion capture data while evaluating the following research question:
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 ====Comparing Elite Players to Normal Database====
-With a **new blank workspace** in Sift, we are able to start the process of comparing the shoulder angular velocities of the 'Elite' group versus the average population which is saved in the normal database.
+With a **new blank workspace** in Sift, we are able to start the process of comparing the shoulder angular velocities of the 'Elite' group versus the average college pitcher population which is saved in the normal database.
 __**Load 'Elite' Players**__
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 Next, we can begin to construct our normal database queries to retrieve the queries for both the library and workspace summaries for the Z-direction. These are useful when creating the plots and deeper into the analysis when performing SPM.
-When you query the **library summary**, you’re retrieving aggregate data which represents what the “average” collegiate pitcher looks like in terms of shoulder angular velocity in the Z-direction. This data is used to compare the elite pitchers’ SAV to the baseline averages, giving insight into how the elite athletes differ from the norm.
+When you query the **library summary**, you’re retrieving aggregate data which represents what the “average” college pitcher looks like in terms of shoulder angular velocity in the Z-direction. This data is used to compare the elite pitchers’ SAV to the baseline averages, giving insight into how the elite athletes differ from the norm.
-Workspace summary queries allow you to make more granular comparisons. Instead of looking at overall population means, you can compare individual trials for average collegiate pitchers to those of elite pitchers. This can help in assessing consistency in performance and how much variation exists between trials for elite pitchers versus the average population.
+Workspace summary queries allow you to make more granular comparisons. Instead of looking at overall population means, you can compare individual trials for average collegiate pitchers to those of elite pitchers. This can help in assessing consistency in performance and how much variation exists between trials for elite pitchers versus the average college pitcher population.
 Select the **ND Query Builder** button in the explore page to open the dialog box.
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 __**Library Summary Comparisons**__
-The library summary represents a mean signal derived from a large number of individuals, providing a baseline of what is considered a typical movement for the general college pitcher population. By using this as a reference, you can see how the elite pitchers deviate from or align with the general college pitcher population. By using this as a reference, you can see how the elite pitchers deviate or align with the general population.
+The library summary represents a mean signal derived from a large number of individuals, providing a baseline of what is considered a typical movement for the general college pitcher population. By using this as a reference, you can see how the elite pitchers deviate from or align with the general college pitcher population.
 On the explore page, **Hold Down CTRL** and **Left-Click** both the **Elite_ShoulderAngularVelocity_Z** query as well as the **R_SAV_Z_Lib**. Make sure __Select All Workspaces__ is checked off.
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 {{:sift:tutorials:openbiomechanics_project:elite_vs_nd_libgraph.png?600|}}
-This plot shows the comparison of elite pitcher shoulder angular velocity for the internal-external rotation signal (Z-direction) versus the normal database mean for the same, which represents the general college pitcher population. Typically, the expectation going into this investigation was that elite pitchers tend to have a higher shoulder angular velocity in order to increase pitch speed. However, the data presented in the graph shows an unexpected result: the mean shoulder angular velocity in the Z-direction for elite pitchers (blue line) is lower than that of the normal database mean (red line). Despite this, the significant dispersion in the elite pitchers’ data (as shown by the shaded area) indicates a wide variability. This suggests that while the average elite pitcher in this sample has a lower angular velocity, certain individuals in the elite group may achieve much higher velocities.
+This plot shows the comparison of elite pitcher shoulder angular velocity for the internal-external rotation signal (Z-direction) versus the normal database mean for the same, which represents the general college pitcher population. Typically, the expectation going into this investigation was that elite pitchers tend to have a higher shoulder angular velocity in order to increase pitch speed. However, the data presented in the graph shows an unexpected result: the mean shoulder angular velocity in the Z-direction for elite pitchers (blue line) is lower than that of the normal database mean (red line). To get a better understanding of the differences between the elite level and average collegiate pitcher population, we can move on to performing further statistical analysis such as SPM.
-Several factors could explain this discrepancy. First, the difference in means might arise from variations in population size - where the normal database has more representation and elite pitchers, though fewer in number, show greater variability. Second, elite pitchers may employ different mechanics or strategies, relying less on shoulder angular velocity and more on the other parts of their body, such as trunk rotation or lower-body movement, to generate higher pitch speeds.
 ====SPM Analysis====
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 First, we can navigate to the “Analyze” page to begin to perform our SPM.
-Select the **Elite_ShoulderAngular_Z** and **R_SAV_Z_Workspace** by holding down CTRL.
+Select the **Elite_ShoulderAngular_Z** and **R_SAV_Z_Workspace** by holding down CTRL and selecting all workspaces.
-Switch to the __SPM Tab__ and select Compute SPM, the dialog box should open.
+Switch to the __SPM Tab__ and create a GLM. The following information can be inputted into the dialog box:
+GLM Name: GLM_SAVZ
+\\
+Group by: Group
+Then move to the statistics page, and select Compute SPM, the dialog box should open.
 {{:sift:tutorials:openbiomechanics_project:spm_dialogbox.png?400|}}
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 Group 2: R_SAV_Z_Workspace
-{{:sift:tutorials:openbiomechanics_project:spm_graph.jpg?800|}}
+{{:sift:tutorials:openbiomechanics_project:spm_graph_editedalpha.jpg?800|}}
-The threshold value is conveyed by the horizontal red dashed line at the top represents a critical threshold for statistical significance. If the t-statistic exceeds this threshold at any point along the curve, that portion of the motion is statistically significantly different between the groups compared. Due to the close relationship between the two groups, the **threshold is set to 0.50**. In this case, any t-statistic values exceeding 0.5 would be considered significant.
-In the early region of the plot, the t-statistic approaches the threshold (between 0-10% and again around 20% of the normalized motion), although it does not exceed it. This could indicate that the most substantial differences actually do exist during the pitching motion at the max height of the ball, yet the follow through is relatively uniform for most pitchers.
-The curve’s shape is relatively jagged, indicating high variability in shoulder angular velocity, as explained in the comparison plot.
+The SPM plot analysis, using an alpha level of 0.05, reveals a critical t-statistic threshold of 2.73, indicated by the dashed red line at the top of the graph. This threshold represents the point beyond which differences in shoulder angular velocity (SAV-Z) between elite pitchers and the general collegiate population would be considered statistically significant. However, throughout the entire range of normalized motion, the observed t-statistic consistently remains below this threshold, suggesting that there are no statistically significant differences in SAV-Z between the two groups.
 ====Conclusion====
-Using Sift, we were able to streamline the analysis of shoulder angular velocity in the Z-direction between elite and average collegiate pitchers. The tool enabled precise comparison through query building and statistical parametric mapping (SPM). Our findings reveal that elite pitchers, despite having a lower mean SAV-Z, exhibit greater variability. This highlights the complexity of elite-level pitching mechanics, where factors beyond shoulder angular velocity likely contribute to their superior performance.
+Using Sift, we were able to streamline the analysis of shoulder angular velocity in the Z-direction between elite and average collegiate pitchers. The tool enabled precise comparison through query building and statistical parametric mapping (SPM). Although our results showed that the Elite Pitcher group had a lower mean SAV-Z than the average college population, the SPM showed no significant differences between the two groups. Due to the complexity of elite-level pitching mechanics, factors beyond shoulder angular velocity may be contributing to their superior performance such as lower body kinetics, trunk rotation, core stability and more.
 ====References====
 **Data Set**: OpenBiomechanics Project is an initiative started by Driveline Baseball Research & Development to provide raw (in the form of cleaned C3D files) and processed (full signal + point of interest) sports biomechanics data to the general public [[https://github.com/drivelineresearch/openbiomechanics|[2]]]