CBSE Class 12 Physical Education Notes Chapter 10 Kinesiology, Biomechanics and Sports is part of Class 12 Physical Education Notes for Quick Revision. Here we have given NCERT Physical Education Class 12 Notes Chapter 10 Kinesiology, Biomechanics and Sports.
Physical Education Class 12 Notes Chapter 10 Kinesiology, Biomechanics and Sports
Axes and Planes
The body performs movements through a plane and around an axis.
Axis An axis is an imaginary line about which the body (or limb) rotates. It can be divided in three parts
- Frontal Horizontal Axis Axis of the body that passes horizontally from side to side at right angles to the sagittal plane.
- Vertical Axis Axis of the body that passes from head to foot at right angles to the transverse plane.
- Sagittal Horizontal Axis Axis of the body that passes from front to rear lying at right angles to the frontal plane.
Plane A plane is an imaginary flat surface along which a movement takes place. It can be divided in three parts
- Sagittal Plane A vertical plane of the body which passes from front to rear dividing the body into two symmetrical halves.
- Transverse Plane Any horizontal plane of i the body which is parallel to the diaphragm also called the’horizontal plane
- Frontal Plane Plane of the body which passes from side to side at right angles to . the sagittal plane also called the coronal plane.
Types of Movements
Physical activity is made possible by movements and motions. Every movement takes place, in one plane and around one axis. They are categorised by movement type as follows
- Flexion It takes place when the angle decreases between the two bones attached to a joint.
- Extension It takes place when the angle between the two bones attached to a joint increases. Both flexion and extension occur in the sagittal plane about the frontal axis.
- Adduction It is a movement laterally toward the middle of the body.
- Abduction It is a movement laterally away from the middle of the body. Both adduction and abduction occur in the frontal plane about the sagittal axis.
Major Muscles Involved in Running, Jumping and Throwing
Educating ourselves on the muscles we use while exercising is important. The more we know about our body, the better we can protect it by treating it with care and avoiding injury.
Running on a regular basis has many benefits, including weight loss, stress relief and maintaining a strong and healthy body. As it is one of the more physically exerting activities, it can also cause damage to our body such as a pulled hamstring or dislocation of our knee caps. With a little knowledge, we can help prevent these injuries with the right equipment and by properly stretching our muscles before the run.
Primary Muscles Used While Running
Primary muscles will get the most impact from movement and therefor? should receive more care. Primary muscles while running will include – your quads (quadriceps femoris), hamstrings, gluteus maximus, iliopsoas, and your calf muscles.
Quads (Quadriceps Femoris)
Quads are muscle groups of four basic muscles located on our front thighs. They are
- The rectus femoris
- The vastus medialis
- The vastus lateralis and
- The vastus intermedius.
Our quads are responsible for moving two of the joints used in running, our knee joint and our hip joint. They work together to straighten our knees and bend our hips. If we are interested in strengthening our quad muscles, we should consider doing squats and lunges. Increasing strength in our muscles apart from running can decrease our risk of injury and increase our speed.
Hamstrings and Gluteus Maximus
Our hamstrings are made up of four muscle parts on the back of our thighs. These are known as
- The semitendinosus
- The semimemb ranosus, and
- The biceps femoris (two parts: long head and short head).
These four parts of our hamstrings allow us to flex our knees. The semitendinosus, semimembranosus and the long head biceps femoris work together to extend the hips. As you may have noticed, your hamstrings work opposite your quads in how your knees and hips move, creating a systematic medley that works well for your body.
The gluteus macimus is the largest of the gluteal muscles. You will recognise it easily as it is the muscle that contributes most to creating the shape of the buttocks, better known as butt or rear-end. This muscle will help you keep proper erect posture by extending your hips.
Hip Flexors (Iliopsoas)
Our hip flexors (or iliopsoas), like our quads, is comprised of a muscle group of two muscles
- The iliacus
- The psoas major
To our right, the shortest muscle, the iliacus, begins on our pelvic crest (the iliac fossa) and stretches over to our thigh bone (femur). The larger of the muscles, the psoas major, stretches from our T-12 spinal vertebiae to our Lj-5 spinal vertebrae and there attaches to the femur. These two muscles work together to help our hips flex. The iliopsoas are often the culprit behind severe hip pain. If you experience hip pain while running, you should stop your routine immediately, and go to see your doctor or a chiropractic specialist. Do not begin running again until they have determined it to be safe.
Our calf muscles are located on the back of our leg, belovv our knee. Though many anatomists see the calf muscle to be a single muscle (triceps surae), most say that it is a muscle group, like our quads and hip flexors. This group consists of two main muscles, the
- The gastrocnemius and
- The soleus.
Our calf muscles will allow us to flex our knee and planter flex our ankle. Like our quads, our calf muscles can be strengthened by doing squats. Other good strength-building exercises would include calf muscle raises and skipping!
Only a small percentage of people has the natural ability to jump high. That is why it is important to train properly to improve your hops if you are not among that group. Part of this battle is knowing just what muscles are most important to lift your body off the ground. The stronger you make them, the more power you will have to jump high.
The quadriceps rest on the front of the thighs and they have four components the vastus medialis, vastus lateralis, rectus femoris and vastus intermedius. During a jump, you perform hip flexion and knee extension, which both activate the quadriceps. Hip flexion takes place when you move your thigh toward your stomach knee extension takes place when you straighten your leg. A squat is a specific exercise that can help you gain more strength in the quads.
The hamstrings are opposing muscles to the quadriceps and have an opposite function. You activate your hamstrings through hip extension and knee flexion. Hip extension takes place when you bend your knee and move your heel toward your butt. Hip extension also causes you to work the glutes. From an anatomical standpoint, the hamstrings have three parts: the biceps, femoris, semimembranosus. All parts get activated during the lowering phase and the explosive phase of a jump. A squat works the hamstrings, but you can place more emphasis on them by doing a lunge.
The hip flexors run from the lower stomach to the top of the thighs. They consist of the psoas major and iliacus, and because of this, they are often referred to as the iliopsoas. As the name implies, these muscles get activated when you flex your hip, in similar fashion to the quads. Although these muscles are small, they are important for explosive motions like sprinting and jumping. A lying leg raise is a good exercise to strengthen the hip flexors.
The calves have two parts : the gastrocnemius and soleus. The gastrocnemius has a lateral head and medial head and it is easily seen on the back of the leg right below the knee. The soleus sits anterior, or in front of the gastrocnemius. Both parts function to plantar-flex the foot. This motion occurs when you jump off the ground and point your toes downward. Jumping rope is a good cardiovascular exercise to train these muscles because of the repetitive hopping you do on your toes. A tuck jump is a good exercise to work your calves because it is specific to jumping.
Following are the muscles which are used while throwing any thing like ball, football etc. .
The deltoids are the muscles of your shoulder, which play a crucial role in rotating your aim. Always warm up adequately by performing arm circles to avoid injuring your rotator cuff, while performing shoulder exercises.
Your triceps are located on the back of your upper arm and aid in the process of extending your arm at the elbow. This action helps you release the ball with force and push it in the desired direction. To strengthen your triceps efficiently, perform exercises such as triceps pushdowns with a rope or pulley and close-grip bench presses.
Your latissimus dorsi, often referred to as your lats, are located on either side of your spine. These large muscles help produce force for throwing and help transfer energy from your legs to your upper body. Among the best exercises for strengthening your lats are pull ups, seated cable rows, and bent-over barbell rows.
While many people exercise their abdominal muscles in hopes of attaining a six-pack, this muscle group is highly functional as well. A strong core facilitates the transfer of power from your lower body to your upper body, enabling your throws to benefit from the strength of your legs. Among the best exercises for your abs are hanging leg raises and swiss ball crunch.
The quadriceps is the major muscle group located on the front of your thigh. This large group of muscle tissue helps you power the ball toward your intended target as you step into your throw. Among the most effective exercises for the quadriceps are the barbell step-up, barbell lunge and barbell squats, which also work your abdominal muscles.
Newton’s Laws of Motion
Sir Issac Newton made three laws of motion which are explained below
- Newton’s First Law of Motion This law is also known as law of inertia. This law states that a body at rest will remain at rest and a body in motion will remain in motion at the same speed and in the same direction till any external force is applied on it to change that state.
- Newton’s Second Law of Motion This law states that the rate of change in acceleration of an object is directly proportional to the force producing it and inversely proportional to its mass.
- Newton’s Third Law of Motion This law states that to every action, there is always an equal apd opposite reaction. This law . describes what happens to a body when it exerts a force on another body. These three laws are still being used to this day to describe the kinds of objects and speeds that we encounter in everyday life.
Application of Laws of Motion in Sports
- Softball The ball is hit into the air. Eventually, gravity will act on the ball, pulling it down to the ground. Then, it will roll until friction between the ball and the grass stops it.
- Soccer When a soccer ball is kicked into the air, gravity will pull it back to the ground. Then, it will continue to roll until friction between the ball and the grass slows it down.
- Dance When a dancer leaps, he/she only stays in the air for a short amount of time because air resistance and gravity works against them.
- Basketball When a basketball is shot, it takes a parabolic path due to gravity acting on it. Then it slows down due to air resistance and fluid friction.
If a baseball player hits a ball with double the force, the rate at which the ball will accelerate (speed up) will be doubled. Football players can slow down, stop or reverse the direction of other players depending upon how much force they can generate and in which direction.
A swimmer propels herself through the water because the water offers enough counterforce to oppose the action of her hands pushing, allowing her to move. An athlete can jump higher off a solid surface because it opposes his body with as much force as he is able to generate, in contrast to sand or other unstable surface.
Projectile and Factors Affecting Projectile Trajectory
A projectile has a single force that acts upon it-the force of gravity. If there were any other force acting upon an object then that object would not be a projectile. Projectile motion refers to the motion of an object projected into the air at an angle.
Factors Affecting Projectile Trajectory
When the human body or an object is projected through space, three forces influence the course of flight
- Propelling Force The propelling force produces certain effects depending upon its point and direction of application. If the application is directly through the projectile’s centre of gravity, only linear motion results from the force. As the propelling force is moved farther from the centre of gravity, rotatory motion of the object increases at the expense of linear motion.
- Force of Gravity As soon as contact is broken with a projected object, the force of gravity begins to diminish the upward velocity of the object. Finally, gravity overcomes the effects of the upward component of the projectile and the object begins to descend.
- Effects of Air Resistance As the speed of an object increases, air resistance has a greater retarding effect.
The force acting along two surfaces in contact which opposes the motion of one body over the other is called the force of friction.
Friction is of two types
- Static Friction The opposing force that comes into play when one body tends to move over the another surface but the actual motion has yet not started is called static friction.
- Dynamic Friction It is the friction between two surfaces that are in relative motion with respect to each other. It is the opposing force that comes into play when one body is actually moving over the surface of another body.
Methods of Reducing Friction
- Polishing By polishing the surfaces in contact, they become smooth and the force of friction reduces. Many implements like the discus are painted to reduce friction.
- Lubrication The lubrication of surfaces makes them slippery and this reduces the force of friction.
- Streamlining Friction due to air is reduced by streamlining the shape of the body. The aroplanes are made with a sharp front to reduce friction.
- Use of Ball Bearings Ball bearings are used to reduce the force of friction. Many sports require more friction and other need lesser friction. In athletics, the shoes are designed to increase friction so that better speed can be generated.
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