Matthew Clark

Jimmy Kight

Jay Higginson

Introduction:

As avid sport fans, we chose completing a slam-dunk in the 1988 slam-dunk contest. Fun fact, Michael Jordan won the dunk contest in 1997 and 1988. His dunk in 1988 has long been considered iconic because it was the first of its kind. Since that prolific dunk he became known as, . Our analysis project will focus primarily on his free throw line dunk. We will be focusing on the hip down to the foot. The video is from a sagittal plane and our primary focus will be his jumping leg, which in this case is his left leg.

We will be analyzing the kinematics, kinetic and musculoskeletal systems throughout the of take-off to the point of landing.

We will be breaking down the fundamental movement of MJ’s dunk into three phases in the sagittal plane. The absolute time portion of the video we are focusing on will be one second.

The relative time will be broken down into 0%, 50% and 100%. Since the view we chose is completely sagittal we must look at all the factors that are incorporated with the sagittal plane.

As you can see in this angle we see that Michael Jordan is preparing for his dunk. The sagittal plane consists of several fundamental movements, most of which are apparent in this freeze frame. The fundamental movements are: flexion, extension, hyperextension, hyper flexion, plantar flexion and dorsi flexion. As Michael Jordan approaches his takeoff point, his knee is in flexion to prepare muscle contraction to overcome gravity and ground reaction force. His foot begins to dorsi flex as the load begins to be applied, while his hip becomes slightly flexed.

Absolute time of MJ’s dunk is less than one second, because according to Sportscenter’s

Sport Science it is physically and humanely impossible for someone to jump and stay airborne without any assistance for longer than one second. Absolute time is defined as the actual time measurement that being said we chose to mainly focus on the time from takeoff time to dunk time.

Relative time:

100% 50% 0% 1s .5s 0s

Displacement is the change in position from beginning to end. MJ’s body position from beginning to end is very similar, other than the force. He is working against ground reaction force in the beginning and ground reaction force is working against him at the end. The forces acting upon him between take-off and landing are force of gravity and the force of drag.

Displacement:

Landing Takeoff

Position: #3 #2 #1

20o 60o 60o

140o 135o o 135 o 150 80o

The position that we are viewing is 3D linear in the sagittal plane. We are looking at a three-stage process of the dunk. Position one focused on the takeoff and loading aspect, position is his athletic stance in the air, and our third position is preparation for impact as well as the impact itself. While looking at position two he is in a forward tilt, preparing for impact of his dunk. The rim he is reaching towards is fixed stationary and he must make the adjustment to successfully complete the motion.

Kinetics is the study of the relationship between motion and its causes, namely forces and torque. Our analysis of force was to determine the force required for MJ to successfully take-off from the free throw line and complete the dunk. His mechanical disturbance, or push, should be of high intensity as to successful jump the 13.5 feet required to finish the dunk. His force is created by a combination of acceleration and momentum, which is a result of work, energy and power.

Torque is created at the hip, knee and ankle. Torque is defined as the turning affect created by a force about an axis. Torque is applied to the bones and compression, and the muscles inflection and extension against ground reaction force.

Force of gravity is working against Jordan’s attempt to jump higher than the rim. The force of drag is against his forward motion. The kinetics he is working against with speed toward takeoff and muscle exertion against the hardwood floor.

Work is explained as the product of force and the amount of displacement in the direction of that force. In this specific example we see that Michael Jordan’s work is solely focused on jumping the 13.5 feet to successfully complete his slam dunk. As we see in the video he clearly initiates enough work to complete the task. When we discuss energy we primarily discuss potential and kinetic energy. In this case we see both types. The kinetic energy is his body in motion, picking up speed and preparing his body for jumping. We also see potential energy because of the speed that he generates. The faster he runs the more likely it is that he will be able to jump farther.

Musculoskeletal: Jordan Free Throw Dunk

After watching the video and determining what we wanted to look at, we decided to focus on the lower half of the body. Since the lower half includes some of the biggest bones and muscles, all of them are working together to help in propelling Jordan into the air, overcome gravity, and travel the distance to the hoop. Michael Jordan is 6’6” so he has very long legs and strong muscles. Being a all-star, we concluded that he would have both type 1 and 2a muscle fiber types. Able to perform short explosive sprints up and down the court but also able to stay on the court for long periods of time running up and down. This helps in jumping or dunking by being able to explode up into the air but not using all of his energy to not be able to continue in the game.

The muscles that were used in his free throw dunk include; the gluteus maximus, hamstrings, quadriceps, calves, and the tiny muscles of the foot. All of these muscles can be used as both agonist and antagonist to help with stabilizing, flexion, and extension. On his approach or point of takeoff, we see a slight squat, activating the hamstrings to contract

(agonist) and the quadriceps to extend (antagonist) as well as the ankle to slight dorsiflexion.

This causes a loading period in which the muscles are now ready to be release to cause an upward movement into the air. Once liftoff occurs, the muscles will then change, hamstrings will extend becoming the antagonist, quadriceps with go into flexion (agonist) and the ankle with plantar flex to push off the ground and into the air. Upon landing, the muscles will return to the beginning squat stance to help prepare them for compression and make the landing easier to reduce injury to occur. We also see biarticular muscles with both the hamstrings and calves in helping with movement. Biarticular muscles are muscles that cross at two joints.

Hamstrings both cross at the hip and knee joint in helping with one another in walking, running, and in this case jumping. This can be seen as a lever arm in helping with flexion/extension of the leg and hip in producing movement. The calf muscle crosses at the knee and ankle joint.

This helps in the movement of the ankle to propel us to walk and balance as well in exploding in a jump. The fiber types within Jordan’s body vary from type 1, type 2a and pennate. Type 1 is more endurance capabilities being able to sustain longer activities such as running up and down the court. Type 2a is more fast twitch using more energy and not lasting as long as type 1 would. Pennate fibers found in his calf muscle, run at an angle to the tendon rather the vertical causes an increase in force and decrease in range of motion. In Jordan’s dunk, he used mostly type 2a and pennate to propel him in the air with a short explosive jump and the pennate fibers in his calves increase a force to explode by increasing the angle.

With all of these muscles working to help run and jump, there are some other muscles and tendons that help in stabilizing them. Some of them include the adductors and abductors, iliotbial band, tibialis posterior. Adductors and abductors help in with supporting the hip keeping it stable and strong. Iliotibial band helps in stabilizing the knee from lateral movement.

The posterior tibialis stabilizes the shank and supporting the medial arch of the foot.

Hip Joint

Articulation Hip Hip

Joint Movement Extension Flexion

Motive Force Muscle Gravity

Resistive Force Body weight Muscle

Functional Muscle Group Quads Quads

Muscle Action Concentric Eccentric

Body Parts Stabilizing Core, ankle, knee Core, ankle, knee

Active/passive insuffiency Both or neither Knee Joint

Articulation Knee Knee

Joint Movement Flexion Extension

Motive Force Muscle Gravity

Resistive Force Body weight, gravity Muscle

Functional Muscle Group Hamstrings Hamstrings

Muscle Action Concentric Eccentric

Body Parts Stabilizing Hips, ankle, Hips, ankle

Active/passive insuffincey Active

The bones of the lower body are some of the biggest in our body. These help with supporting of the weight, muscles and other bones in our body to keep us up right and moving.

Bones can be either cortical or cancellous. Cortical bone is the hard outer layer of our bones that help in support the whole body, protect the organs, provide levers for movement and store and release calcium. Cancellous bone is like a sponge, found at the ends of the bones or the joints. Bones used in our analysis are the pelvis, femur, tibia, fibula, and ankle. There are four types of bones; Long bones- are all limbs which have a diaphysis or the shaft which make the length of the bone and an epiphysis which are the rounded ends that connect the joints together. Short bones- are for strength that help with support, they are compact and can limit movement. Flat bones- provide protection as well as muscle attachment. Sesamoid bones- are bones within a tendon to help in protecting the tendon and increase the moment arm. All range from the four types of bones: long bones; the femur, tibia and fibula Short bones; talus, calcaneus, tarsals, phalanges Flat bones; patella and sesamoid bones; also the patella and the two tiny bones on the bottom of our foot by the first phalange. Some bones, like the femur, tibia and fibula, helping in maintaining weight and support by compressing to absorb impact to make it less stressful on the body. Just enough to help in support rather than taking all and potentially breaking of the bone, which muscles help as well. These bones also serve as muscle attachment points for the muscle to be able to flex and extend. This is where the biarticular muscles are able to function. With jumping, Wolf’s Law can have an effect on the bones. Bones increase/decrease in strength depending on the load on a bone. In Jordan’s dunk, the load on his bones are not server enough to cause a decrease in strength rather increase in helping with the propelling of his body into the air.

The visco-elastic properties in our analysis we believe could not be determined because he did not perform any movement that needed to be corrected and the force length change in his muscles did not cause any problems.

In conclusion there were several factors that influence Michael Jordan’s ability to successfully complete this phenomenal dunk. Aspects of kinematics, kinetics and the musculoskeletal has been described in detail in the above text.