Posts Tagged pitching mechanics
Mechanics: The Effects of Loading Rate
Just wanted to drop a short post in about loading rate as it relates to the humerus and possibly the connective tissue in the pitching arm during the throwing motion.
In Humeral Torque in Professional Baseball Pitchers, Sabick et al. concluded that “pitchers who elbows were more extended at stride foot contact tended to have lower peak humeral torques.”
So, in theory, an extended elbow at foot contact but prior to the maximum external rotation would decrease stress on the humerus. Remember that in Correlation of Throwing Mechanics With Elbow Valgus Load in Adult Baseball Pitchers by Aguinaldo et al. that increased elbow flexion was closely related to reducing valgus torque, so an extended elbow throughout the motion is not necessarily ideal.
Also notable is the fact that bone is sensitive to loading rate and not just peak values of stress – therefore, the faster and harder the humerus (and the connective tissue) is loaded, the more danger there is with regard to injury.
Many people focus on the total load and stress on the bone or connective tissue as the failure point of the body’s working parts and pieces, and indeed many laboratory (in vitro) studies simulate only this variable. As Sabick et al. pointed out in the aforementioned paper:
Simply comparing dynamic pitching biomechanics data to bone strength data from in vitro studies is actually over-simplifying the problem. Bone strength is sensitive to loading rate. Differences between loading rates in the laboratory and those occurring during pitching suggest that the data are not directly comparable. In addition, simple torsion is generally simulated in laboratory tests, but the situation is much more complicated in vivo. There are additional components of force and torque acting on thehumerus at the same time the humeral torque peaks. All of the force and moment components contribute to the state of stress in the bone,which changes as a function of time.
As I have often said, Humeral Torque in Professional Baseball Pitchers is one of the most influential papers written about pitching biomechanics as it relates to how we train and instruct our clients. For more information, check out our Pitching Program and see if it’s right for you. As you talk to coaches and other instructors, ask them about the this paper, or simply ask them what research papers and scientific principles have guided their methods.
Kinematic Analysis: Wrist to Elbow Relationship
Posted by Kyle in motion analysis on January 17, 2010
We talk a lot on this blog about training for baseball, but not much about mechanics or the actual pitching motion in general. Today I’d like to take a quick look at one part of pitching mechanics that we study: The relationship between the pitching arm wrist and the pitching arm elbow during the late-cocking phase of the pitching delivery.
Late-Cocking Phase (click for large image)
In the late-cocking phase of the pitching delivery, there are very high forces placed on the shoulder and arm segments as they rotate upwards of 937 degrees/second and 1160 degrees/second, respectively. Part of what can cause the serious forces on the elbow in particular is how the arm lays back in Maximum Shoulder External Rotation (MER).
Billy Wagner at MER
How the arm reaches MER is vitally important – in pitchers with timing flaws, the forearm violently lays back behind the elbow in rapid succession, causing significant torque on the elbow. However, this can be minimized with training and slight mechanical changes, both of which are beyond the scope of this introductory article.
One way we study the relationship between the pitching arm wrist and elbow is to perform a trajectory analysis on a pitcher, measuring the path of the pitcher’s driveline and the rate of change of various arm segments. While I can’t show you any video from my current clients (privacy reasons and all), I can show you some anonymous data from a first-time client that I have handy. This pitcher is a youth pitcher who had his recent entry evaluation with high-speed footage taken within the past month. The chart below details the relationship between the pitching elbow (blue) and the pitching wrist (red). Also shown in the chart are the rates of change (delta) between each time interval (0.00476 seconds, if you were wondering!) as well as the delta between each delta! (Absolute values were used in measuring the rate of change of the deltas.)
Trajectory Chart - Relationship Between Wrist and Elbow
What does this chart tell us? Well, the red and blue numbers are measured in pixels and detail the wrist and elbow’s paths, respectively. In this student’s case, the pitching elbow rapidly outpaces the pitching wrist, causing the forearm to lay back fairly rapidly in MER. The sum of all the deltas in the right-hand column expresses the absolute difference in rates of change between the two segments of the arm and tells us something about timing flaws. While not every pitcher should be within a given range, this is but one more variable that we use to analyze a pitcher’s mechanics and can tell us a lot about how the arm is used.
Our Other Website
Be sure to check out our other general baseball blog at Driveline Mechanics. We discuss pitching/hitting mechanics, sabermetrics, and general discussion about MLB!
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