Category Archives: Anatomy and Diomechanics

Muscle groups in Selected Activities

Muscle work in groups to produce specific joint movements. Efficiency of movement can be improved upon by studying the mechanics of movement at a joint, and making necessary changes. (Muscle Memory)

Training for strength and flexibility can influence the efficiency of movement.

Lifting and Carrying Objects-

Place the object close to or between spread feet, squat with an erect trunk, activate abdominal muscles and tilt pelvis backward. Use the hip and knee extensors to generate slow, smooth force. Carry the lifted object close to you body.

Common Mechanical Errors: Walking and Running

Stiff-legged running increases rotational inertia, and increases joint stress. Keep joint movements in the anterior-posterior direction to eliminate trunk rotation. (running strait)

Do not propel too high off the ground and reduce impact by running softly and quietly.

Common Mechanical errors: Throwing and Striking

The more joints involved in a throwing motion, the more speed can be produced. Lack of trunk rotation and poor coordination of timing with shoulder movement can result in low velocity.

When striking, rotate the trunk to increase impact of the strike. Hip, trunk and upper limb movements should follow each other with fluid timing.

Beginners often stop one movement before beginning the next. Increased bat velocity results in increased impact on the ball, and greater transfer of momentum.

 

** Disclosure- Everything from this article was found in the book Fitness Professional’s handbook Sixth Edition**

Basic Biomechanical Concepts fro Human Movement

Biomechanics is the study of tho our joints in our body move and some forces that contribute to those movements. Learning to understand the Biomechanics of the human body is necessary to fully understand our movement.

Torque

Torque is an expression of rotational force and all human movement is rotational in nature. Our Limbs act as levers that rotate around fulcra.

Torque is the product of magnitude of force and the {force arm}

The equation for Torque is T=F X FA [Torque equals Force x Force Arm]

When two for es produce rotation in opposite directions, one is the resistance force (R) and its force arm is called the resistance arm (RA). Force generated by R x RA is called Resistance Torque (TR)

Force Arm- is the perpendicular distance from the axis of rotation of the joint to the direction of the force from its point of application (where the muscle attaches to the bone being moved).

Resistance arm-is the distance from the axis of rotation to the center of gravity of the moving limb.

Torque and Exercise-

While exercising, the force arm is the distance from the axis pint (joint axis of rotation) to the point of attachment of the muscle on the bone being moved. The resistance arm is the distance from the axis of rotation to the center of gravity of the moving limb.

Holding a dumbbell lengthens the resistance arm by moving the center of gravity further away from the fulcrum, the longer the resistance arm, the more torque is needed to produce movement.

Torque varies as a limb a limb moves through the joint’s range of motion due to change in the length of the force arm.

Rotational Inertia-

Rotational Inertia the resistance to change in the rotation of a body segment around a joint axis. It depends on the mass of the segment and its distribution around the joint.

For example a lower limb has more rotational inertia than an upper limb not only because it is heaveier but also because its mass is concentrated a greater distance away from its axis of rotation.

Inertia can be manipulated by changing the joint angle (for example) by flexing the knees during running, we move the mass closer to the axis, decreasing inertia.

Angular Momentum-

Angular momentum is the product of angular inertia x angular velocity. The faster a body segment moves, and the greater its rotational inertia, the greater its angular momentum.

The amount of force needed to change angular momentum is proportional to the magnitude of momentum.

Angular Momentum and Exercise-

A faster movement, a greater mass, or a greater desired decelerate requires grater muscle force to slow down the body segment.

Muscles can be injured if they are not strong enough to decelerate the force generated from ballistic movements.

Ballistic Movement-a high-velocity musculoskeletal movement, such as a tennis serve or boxing punch, requiring reciprocal coordination of agonistic and antagonistic muscles

 

 

***disclosure: everything in the article I found in the book Fitness Professional’s Handbook Sixth Edition***

Skeletal Muscle and Forces that Cause Movement

Now on to Skeletal Muscle and Movement!

Picture found HERE

Skeletal Muscle Properties: Are voluntary which means you must think of it to do it, which consists of millions of individual fibers.

There are 4 different skeletal muscle fibers your Fascicles, Perimysium, Epimysum and your Tendon.

Fascicels are a bundle of fibers grouped together.

Perimysium is the connective tissue surrounding the fascicles.

Epimysium is the tissue encasing the entire muscle.

Tendon is the passive part of the muscle that is made up of tough elastic tissue, your tendon is what attaches the muscle to bone.

Some Forces that cause movement are muscle contraction, gravity, outside forces and the same forces that cause movement can also prevent movement as well. Which is also known as Newton’s first law of motion!

Newton’s Fist Law of Motion– A body in motion stays in motion until acted on by an outside force.

There are 3 Muscle Actions!

Concentric Muscle Action: This is the shortening phase of a movement such as a pull up or curl, when muscles pull on bones to bring your body segments closer to each other and must generate enough force to overcome the force of gravity.

~Movements that are done opposite the pull of gravity are considered concentric~

Picture found HERE

Eccentric Muscle Action: (letting go) Eccentric muscle action occurs in the direction of gravity, when the muscle resists the pull of gravity in order to control the movement. When the muscle lengthens as it produces less force.

Isometric Muscle Action: (when you hold it) When muscle force is equal in magnitude to the opposing force and length does not change, also when force is produced without a change in length.

Picture found HERE

Agonist– The main muscle working

Antagonist– Opposite side of Agonist

Achieving Stability: There are many things that go along with achieving stability. The ability to maintain a balanced position after a disruption of balance, it requires the center of gravity to fall within the base of support, changing foot and body positions. A wide base of support and lower body position will increase stability and a narrow base and elongated body position will reduce stability

 

 

 

 

The Joint Structure, Function and Movement

First things first, joints are where two or more bones meet, which are classified according the movement that takes place.

Lets get your ligaments and tendons out of the way. There is a big difference when it come to ligaments and tendons. Your ligaments are what connect your bones to each other across all joints and your tendons are what connect your muscle to the bone.

There are 3 different types of major joints, your Synarthrodial Joints, Amphiarthrodial Joints and your Diarthrodial (synovial) Joints.

Synarthrodial Joints: (the lines of junction of your skull bones are a prime example of the Synarthrodial Joint) they are immovable and are bound together by fibrous tissue that is continuous (attached together in repeated units) with the periosteum.

Periosteum-The dense fibrous membrane covering the surface of bones except at the joints and serving as an attachment for muscles and tendons

Picture found HERE

Amphiarthrodial Joints: These joints only allow a small amount of movement (some more movable than others). These joints are often separated by and disc, which deforms with movement. Some great examples are the tibiofibular, sacroiliac and vertebral joints.

Picture found HERE

Diarthrodial (synovial) Joints: Diarthrodial Joints are your most common joints, they are freely moveable and with great range. Most of your joints that you use during physical activity will be your synovial joints. They are also enclosed by your capsules. Some characteristics of the Synovial Joints are the articulating surfaces of the bones are covered by articular cartilage which reduces friction and contributes to shock absorption between the bones. Your Menisci which is the C-shaped discs between the femur and tibia and reduce friction and provide a shock absorption and Bursae which are sacs of synovial fluid that lay between muscle and bone that are found in your shoulder, hip, elbow and knee. The Bursae reduces the friction and provide a shock absorption.

Picture found HERE

The direction and range of motion of joints is primarily determined by the shape of the bones such as the ball and socket allows for a wide rang and direction and the hinge joints are more limited in direction and ROM (range of motion).

When referring the joint movement you should always be in anatomical position and relate to movement within the planes and about axes.

As shown in previous post HERE their are specific joint movement!

  • Flexion and Extension
  • Abduction and Adduction
  • Internal Rotation and External Rotation.

 

Planes and Axes of Movement

Right now I am learning about the Planes and Axes of Movement. I find it hard and I tend to mix them up a lot so here it goes!

There are three different planes the Sagittal Plane, Frontal Plane, and Transverse Plane all which have perpendicular Axis which are the Anteroposterior Axis, Logitudinal Axis and Mediolateral Axis.

First the Planes:

Sagittal Plane: The Saggital Plane divides the body into right and left segments just like the photo below. How I like to think of it is just like the picture shows, cut your body into two right down the middle.

The Frontal Plane: The Frontal Plane divides the body into anterior and posterior segments. Shown in the picture below.

Anterior-situated at or directed toward the front.

Posterior-directed toward or situated at the back

Transverse Plane: The Transverse Plane divides the body into the upper and lower segments as shown in the picture below. Once again as if you are cutting your body into two.

Picture found HERE

Now on with the Axis: Like I said before all of the Axis are going to be perpendicular to one of the Planes, this helps me remember a little easier!

Anteroposterior Axis: The Anteroposterior Axis will always be perpendicular to the Sagittal Plane, which is where where abduction and adduction occur.

Abduction-Moving the distal segment to the side and away from the body anatomical position.

(Anatomical Position-is when the body is standing in erect position with your arms at the sides and palms are facing forward)

Adduction-is the return of the anatomical position from abduction, which is moving the segment in the opposite direction.

Here is a picture of Abduction and Adduction.

Picture found HERE

Mediolateral Axis: The Mediolateral Axis is perpendicular to the Sagittal Plane, which is where flexion and extension occur.

Flexion-is when you move the distal segment forward and upward in the anatomical position in order to bring two body segments closer together.

Extension– is when moving the segment in the opposite direction of flexion.

Here is a picture of Flexion and Extension:

Picture found HERE

Longitudinal Axis: Is perpendicular to the Transverse Plane, the internal and external rotation occur in this plane.

Internal Rotation-is when turning the segment toward the center of you body from the anatomical position.

External Rotation– is the turning the segment in the opposite direction of Internal, so the return motion.

Here is a picture of internal and external rotation.

Picture found HERE

Now here is a picture of all the Axis

Picture found HERE