Bench Press kinematics
We will be discussing what the person needs to do to achieve optimal performance during the one rep maximal bench press. The bench press is an upper body strength exercise which targets the pectoralis major, anterior deltoid, and the coracobrachialis. In an effort to promote strength increases that promote and benefit everyone. For this exercise we will be performing a one rep max, which is the maximal amount of weight that you are able to move. During this exercise you will experience four phases: acceleration, sticking, maximal strength, and deceleration. We are examining the performance standpoint for this exercise.
The variables that we will be evaluating are time, vertical displacement, vertical velocity, and vertical acceleration. Displacement is the change in position of an object from start to stop, in which the object here is the bar (3). Acceleration is then the change in velocity over time; velocity measures how fast an object is moving in a certain direction (3). The subject will go through 4 stages. Starting with the bar on their chest and moving up, is the acceleration phase. When the person struggles this is considered the sticking phase, which is then proceeded by the maximal strength stage and lastly the deceleration phase as the bar returns to the resting point on the chest (2) During the acceleration phase the subject needs to create enough acceleration to carry them to the sticking point. The main goal is to complete the lift and get through the sticking phase.
At the sticking point, they will need to sustain the acceleration that was created. In the maximal strength region, the body is in the optimal point where you can move the weight. Once you have reached this point, the lift is almost completed. The deceleration phase allows you to slow the acceleration of the bar in order to re-rack. After we found all the phases of our lift, we found the velocity and acceleration by calculating how much time it took to complete each phase and how far the bar traveled, also known as vertical displacement (3) The bar was previously measured and used as a constant to retrieve the other displacement. We next looked at velocity because it equals the change in displacement over the change in time. From that we gathered acceleration by taking the change in velocity over the change in time. The weight of the bar effect the acceleration and velocity because the higher the weight the harder it is to move. Understanding the bench press and the phases that are included, when measuring the variable, all of these phases are important for a successful completion on the lift.
In Figure 2 (see Results) we can see that during the acceleration phase the most force is created to move the bar. Once you hit the sticking region, the force dips for only a short time until the maximal strength phase when the force increases. The force the decreases drastically when in the deceleration phase (2). In the experiment, the acceleration phase was completed in .34 seconds, the sticking region in .66 seconds, maximal strength phase in .71 seconds and lastly the deceleration phase in .55. The entire lift only taking 2.27 seconds. The peak acceleration was during the acceleration phase while the peak velocity was entering the sticking region. The minimal acceleration was in the middle of the sticking region. The minimal velocity was when you enter the maximal strength region. Lastly the maximal displacement was at the very end (2).
Throughout the experiment they used percentage completed to understand and determine the acceleration, velocity and displacement (2). We calculated our variables by using distance traveled, distance over time and then acceleration by velocity over time. This article demonstrates how to evaluate the bench press during the four different phases that we are looking at using variables including vertical displacement, velocity, time, and acceleration. In all, this article helped us to know what we are looking for in regards to patterns associated with each phase and a general understanding of how to evaluate a bench press. Now time to go look at our evaluation!
The variables that we will be evaluating are time, vertical displacement, vertical velocity, and vertical acceleration. Displacement is the change in position of an object from start to stop, in which the object here is the bar (3). Acceleration is then the change in velocity over time; velocity measures how fast an object is moving in a certain direction (3). The subject will go through 4 stages. Starting with the bar on their chest and moving up, is the acceleration phase. When the person struggles this is considered the sticking phase, which is then proceeded by the maximal strength stage and lastly the deceleration phase as the bar returns to the resting point on the chest (2) During the acceleration phase the subject needs to create enough acceleration to carry them to the sticking point. The main goal is to complete the lift and get through the sticking phase.
At the sticking point, they will need to sustain the acceleration that was created. In the maximal strength region, the body is in the optimal point where you can move the weight. Once you have reached this point, the lift is almost completed. The deceleration phase allows you to slow the acceleration of the bar in order to re-rack. After we found all the phases of our lift, we found the velocity and acceleration by calculating how much time it took to complete each phase and how far the bar traveled, also known as vertical displacement (3) The bar was previously measured and used as a constant to retrieve the other displacement. We next looked at velocity because it equals the change in displacement over the change in time. From that we gathered acceleration by taking the change in velocity over the change in time. The weight of the bar effect the acceleration and velocity because the higher the weight the harder it is to move. Understanding the bench press and the phases that are included, when measuring the variable, all of these phases are important for a successful completion on the lift.
In Figure 2 (see Results) we can see that during the acceleration phase the most force is created to move the bar. Once you hit the sticking region, the force dips for only a short time until the maximal strength phase when the force increases. The force the decreases drastically when in the deceleration phase (2). In the experiment, the acceleration phase was completed in .34 seconds, the sticking region in .66 seconds, maximal strength phase in .71 seconds and lastly the deceleration phase in .55. The entire lift only taking 2.27 seconds. The peak acceleration was during the acceleration phase while the peak velocity was entering the sticking region. The minimal acceleration was in the middle of the sticking region. The minimal velocity was when you enter the maximal strength region. Lastly the maximal displacement was at the very end (2).
Throughout the experiment they used percentage completed to understand and determine the acceleration, velocity and displacement (2). We calculated our variables by using distance traveled, distance over time and then acceleration by velocity over time. This article demonstrates how to evaluate the bench press during the four different phases that we are looking at using variables including vertical displacement, velocity, time, and acceleration. In all, this article helped us to know what we are looking for in regards to patterns associated with each phase and a general understanding of how to evaluate a bench press. Now time to go look at our evaluation!
(2) Elliot, B. C., Wilson, G. J., & Kerr, G. K. (1989). A biomechanical analysis of the sticking region in the bench press. Medicine and
Science in Sports and Exercise, 21(4).
(3) King, Deborah. “Kinematics” Hill Center 104. Ithaca NY, 09/02/12. Lecture Type
Science in Sports and Exercise, 21(4).
(3) King, Deborah. “Kinematics” Hill Center 104. Ithaca NY, 09/02/12. Lecture Type