Download biomechanics - Cert IV Fitness PT Loftus

Sutherland College Health & Recreation Semester 2 2012. Version 1
CIV Fitness/S&C
Steven Tikkanen – F129
1
ESSENTIALS OF STRENGTH TRAINING AND CONDITIONING
CHAPTER 4
THE BIOMECHANICS OF
RESISTANCE EXERCISE
THE BIOMECHANICS OF RESISTANCE
EXERCISE
The musculoskeletal system
• The skeleton – (muscles can only pull on bones)
– there are 206 bones in the human body.
• Axial skeleton – skull/cranium, vertebral column,
ribs, and sternum.
• Appendicular skeleton – scapula, clavicle,
humerus, radius, ulna, and wrist and hand
bones, os coxa, femur, patella, tibia, fibula, and
ankle and foot bones.
THE BIOMECHANICS OF RESISTANCE
EXERCISE
• Joints – allow movement between bones.
• Fibrous joint – no movement.
• Cartilaginous joint – limited movement.
• Synovial joint – full movement.
• Hyaline cartilage – covers the end of the bones
that make up synovial joints.
• Synovial fluid – is found in the joint capsule of a
synovial joint.
• Synovial joints can be classified into three
groups.
THE BIOMECHANICS OF RESISTANCE
EXERCISE
1.
2.
3.
•
Uniaxial – rotation occurs about one axis.
Biaxial – rotation occurs around two perpendicular axes.
Multiaxial – rotation occurs around all three perpendicular
axes.
Vertebral column – is your back bone and allows movement
to occur.
THE BIOMECHANICS OF RESISTANCE
EXERCISE
•
•
•
•
•
Cervical vertebrae – 7 bones in the neck region.
Thoracic vertebrae – 12 bones in the upper and middle back
region.
Lumber vertebrae – 5 bones in the lower back region.
Sacrum – rear part of the pelvis.
Coccyx – tail bone.
THE BIOMECHANICS OF RESISTANCE
EXERCISE
Skeletal musculature
• All movements involve more than one muscle.
• Prime mover – (agonist) the muscle most
directly involved.
• Antagonist – muscle in direct opposition to the
agonist. Can be thought of as a break,
especially at the end of the range of motion.
Protection.
• Synergist – assists indirectly in a movement.
Hold scapula in place to allow upper arm
movements.
THE BIOMECHANICS OF RESISTANCE
EXERCISE
Levers of the musculoskeletal system
• First class lever – seesaw. R/F/E
• Second class lever – wheel barrow. F/R/E
• Third class lever – elbow – curls. F/E/R
•
During actual movement the class of lever is
determined by the arbitrary decision of where
the fulcrum lies.
THE BIOMECHANICS OF RESISTANCE
EXERCISE
Variations in tendon insertion
• If the tendon is further away from the fulcrum
what will happen?
Anatomical planes of the human body
• Anatomical position
• Sagittal plane – right and left
• Frontal plane – anterior and posterior
• Transverse plane – superior and inferior
THE BIOMECHANICS OF RESISTANCE
EXERCISE
Biomechanical factors in human strength
•
Muscle Cross-Sectional Area
•
•
All else being equal, the force a muscle can exert is related to
its CSA rather than to its volume.
Arrangement of Muscle Fibres
•
•
Pennate muscle.
Angle of pennation – no more than 15 degrees.
THE BIOMECHANICS OF RESISTANCE
EXERCISE
Biomechanical factors in human strength
•
•
Provides some enhancement of force capability for muscle
contraction at high speed, particularly at the extremes of the
ROM.
Muscle Length
•
Muscles can generate the greatest force at its resting length.
THE BIOMECHANICS OF RESISTANCE
EXERCISE
Back Injury
• Erector Spinae muscles work as cables, such as
a suspension bridge.
• All upper body movements must be
transferred to the ground via the back and
legs.
• This put the back into a mechanical
disadvantage, and therefore must generate
forces much greater than the weight of the
object being lifted.
THE BIOMECHANICS OF RESISTANCE
EXERCISE
Back Injury
•
85% to 90% of disk herniation's occur in L4 to S1.
•
With improper technique the force on the lower back could
be as high as 10 times the weight being lifted.
•
Therefore the back should be in an arched position, as
opposed to a rounded position.
THE BIOMECHANICS OF RESISTANCE
EXERCISE
Intraabdominal Pressure
•
The diaphragm and deep muscles of the torso increase the
intraabdominal pressure.
•
The abdomen is made up mainly of fluid, fluid ball.
•
This fluid ball assists the athlete in lifting the weight by
supporting the vertebral column.
THE BIOMECHANICS OF RESISTANCE
EXERCISE
Intraabdominal Pressure
• This is done by performing the Valsalva
manoeuvre, holding one’s breath.
• This increases the rigidity of the entire torso.
• Dangers are – decreased blood return to the
heart, elevate blood pressure.
• To reduce the side effects one must keep the
airway open, breath out slowly during the
hardest part of the lift.