coolcolj
New member
here is a video + slow mo of a recent vertical jump video I did
http://www.youtube.com/watch?v=4VqFZdMiTKg
Can you notice the double knee rebend I do in my jumps?
I've long noticed I do a bit of rocking on my foot when I jump, due to this double knee re bend. I wonder if I jump like this naturally or is it from all the olys I used to do?
I dip down with my weight on heels, and then scoop my hips forward, and my knees move forward, and then my my weights shifts onto the balls of my feet. You can see this weight transfer in my shoe's soles. It's not just a basic down and up, but a subtle rotary hip motion
After studying my slow mo Jump vid, I finally figured out why I keep jumping forward on my standing jumps. It looks like my body is leaning forward as I finally straighten up before my body leaves the ground. Very strange.
Could be a result of my tight hip flexors, as it doesn't allow my body to fully extend.
also a link of interest - about the knee rebend in olys
http://www.dynamic-eleiko.com/sportivny/library/index.html
http://www.youtube.com/watch?v=4VqFZdMiTKg
Can you notice the double knee rebend I do in my jumps?
I've long noticed I do a bit of rocking on my foot when I jump, due to this double knee re bend. I wonder if I jump like this naturally or is it from all the olys I used to do?
I dip down with my weight on heels, and then scoop my hips forward, and my knees move forward, and then my my weights shifts onto the balls of my feet. You can see this weight transfer in my shoe's soles. It's not just a basic down and up, but a subtle rotary hip motion
After studying my slow mo Jump vid, I finally figured out why I keep jumping forward on my standing jumps. It looks like my body is leaning forward as I finally straighten up before my body leaves the ground. Very strange.
Could be a result of my tight hip flexors, as it doesn't allow my body to fully extend.
also a link of interest - about the knee rebend in olys
http://www.dynamic-eleiko.com/sportivny/library/index.html
high correlation was found between the strength of the hamstrings and the vertical jump results of weightlifters. Furthermore, the vertical jump results of weightlifters have a high, but inversely proportional connection to the speed with which the knees shift under the barbell. The stronger the hamstrings, the higher the vertical jump of weightlifters, the faster the knees shift under the barbell in the "explosion" (4).
The faster this reaction takes place, the more powerful the "explosion", the higher the results.
Research into improving the speed of joint motion has shown that the relative strength of the antagonist muscle in an antagonistic pair can affect the speed of movement (1). The hamstrings are the antagonist muscles to the quads. These muscles act as a "brake" for the quadriceps during the extension of the leg. This is to keep the joint from being straightened faster than it can be prudently stopped.
According to the research in this area: " When the agonist is stronger than the antagonist, the neuromuscular system limits speeds to that the antagonist can safely brake, even if the agonist can make the joint move faster" (1).
Consequently, the recommendation "To make an athlete move faster, training must emphasize the antagonist"(1). In all probability this is the reason for the practical observation in weightlifting that "A lot of squats adversely effect speed"(16). A significant disproportionate strength development between the quadriceps and the hamstrings is, apparently, the reason behind this observation.
The key role the hamstrings can play in weightlifting technique revolves around the so - called stretch reflex and the positive effect the action of these muscles can have on the vertical forces produced by the quadriceps. In the approximately one second it takes to execute the snatch, the hamstrings are stretched and subjected to significant tension as the legs initially straighten when the barbell is lifted from the floor. Then, in virtually the same instant they come into play to flex the knees as they shift under the bar. Finally, a fraction of a second later, the hamstrings flex the legs for the squat under the bar.