Dissecting the Jump
A jump is beautiful example of the muscles and limbs of the body working together in perfect unison to propel the body into the air. The jump is one of the most basic expressions of athletic ability, for thousands of years people have compared how far and how high they can jump. In this article I will examine on a muscular level what happens in the body when we jump, and look at ways of improving your vertical jump.
There are many different types of jump, including jumps from a stationary position, running jumps, single leg takeoff and double leg takeoff. The trajectory of the jump can also differ as we can focus on height or length, or a combination of the two. All of these jumps differ slightly in terms of their muscle recruitment patterns, but the similarities between jumps far outweigh the differences. For the sake of simplicity, in this article I will discuss the vertical jump (vertical jump = a two footed jump from a stationary position, where jumping as high as possible is the objective).
To perform a vertical jump we must produce enough force to propel ourselves into the air, and this force largely comes from a powerful triple extension of the hip, knee and ankle. A triple extension essentially refers to the simultaneous straightening of the hip, knee and ankle from a flexed (crouched) position. This triple extension is found not only in jumping, but is one of the most important movements found in almost all sports and many movements in everyday life. It provides the driving force in movements such as pushing the pedal on a bicycle, and climbing the stairs at home.
If you ask someone to perform a vertical jump, the first movement they will perform will be to crouch down into a quarter squat position. This movement takes advantage of the stretch reflex, and puts the body in the correct position to perform a powerful triple extension. The muscles recruited in this triple extension include some of the most powerful muscles in the body, and include the gluteus maximus (buttocks) and hamstrings (back of the thigh) which act together to straighten you at the hip, the quadriceps (front of thigh) which straighten you at the knee, and the gastrocnemius and soleus (muscles of the calf) which extend you at the ankle.
Interestingly, in the vertical jump these muscles are activated in a sequential nature. Bobbert and van Ingen Schenau (1988) investigated muscle activity during the jump and found that peak activity in the gluteus maximus occurred at the very start of the push, wheras the quadriceps were at 62% of their peak at the initial push off, and peaked 160msec before the feet left the ground. The plantar flexors of the ankle (gastrocnemius and soleus muscles of the calf) were at just 26% of their peak at the start of the push, and peaked at 100msec before the feet left the ground.
Although the powerful muscles of the lower limbs provide the majority of the force in the vertical jump, the role of the upper body and torso should not be underestimated. The muscles of the core play the important role of stabilising the whole movement, and the arms provide additional force to increase acceleration speed and drive the body upwards. In fact, research indicates that arm drive is responsible for between 5-10% of your velocity while jumping (try a powerful arm drive while keeping your lower body still to feel this force in effect).
The vertical jump is a highly trainable movement, and you can significantly improve the height of your vertical jump with appropriate training. This training should include a combination of weight training and plyometrics (including explosive jumping and bounding movements). Below are two of the best exercises for improving your vertical jump.
1) Barbell Back Squat
This exercise correlates highly with the vertical jump, and trains all of the major muscles involved in the jump. It will help you develop powerful legs and a strong core.
2) Hang Clean
The clean makes up the first part the Olympic lift the clean and jerk. This explosive lift requires a fast and powerful triple extension, making it an exercise for improving your vertical jump.