Transcript Applications in Biomechanics

Applications in
Biomechanics
Goals of applied biomechanics:
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1. Performance Improvement: focus
on the different aspects of a technique
and sport training
2. Injury Prevention and
Rehabilitation:
researched and developed by sports
medicine specialists, trainers, and
injured athletes
Continued….
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3. Fitness and Personal Training:
biomechanical analysis can be applied
to both exercise and exercise
equipment
Overview….
1) Performance Improvement:
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Application 1 – The Pre-Stretch
Application 2 – Training: Plyometrics
Application 3 – Equipment Design
1) Injury Prevention & Rehabilitation:
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Application 4 – Injury Risk Assessment
Application 5 – Controlling Momentum
Application 6 – Lifting an Object
1) Fitness & Personal Training:
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Application 7 – Gaining Leverage
Application 8 – Generating Tensile Force
Application 9 – Evaluating Resistance Machines
PERFORMANCE IMPROVEMENT
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Application 1 – The Pre-Stretch
(technique)
 For many skills (tennis serve, slap shot)
the atlete's first action is in the opposite
direction
 Wind-up or preparatory phase
 Is this a good thing or could it lead to an
injury?
 This phase places the muscles into a
stretch prior to using those muscle(s) for
PERFORMANCE IMPROVEMENT
The tension or force generated is dependent
on the muscle's ability to contract
As the muscle is lengthened “passive”
tension is also generated
The connective tissue in the muscle offers
resistance to the stretch which contributes to
the stored elastic energy
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Think elastic recoil of a stretched rubber band
Performance Improvement
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The total tension of the muscle includes both
active and passive components
Therefore the pre-stretch preparatory phase
can be very influential in the force output of a
muscle
If coaches and athletes can improve the prestretch, the action can be more effective
(harder slap shot, tennis serve, etc)
TRAINING:
PLYOMETRICS
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For an exercise to be plyometric, it must
be a movement preceded by an
eccentric (lengthening) contraction
Eccentric lengthening performed before
a rapid concentric contraction produces
the greatest force and power
capabilities
Training: Plyometrics
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The faster the muscle is lengthened,
the greater the concentric force
Therefore, training with pre-stretch prior
to an explosive concentric contraction
will allow for faster and more powerful
change in direction
Equipment Design
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Example: golf
Golf clubs have changed a lot over the
years
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Materials used, length of the club's shaft,
etc.
Athletes must accommodate the changes
in equipment in order to benefit from them
INJURY PREVENTION –
INJURY RISK ASSESSMENT
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From a preventative and rehabilitative
perspective, these principles should be followed:
Resistance training should be progressive
Warm-up should be tailored to the workout
All key muscles must be stretched once warm
Muscle imbalance needs to be addressed (are
there muscles that are heavily used? They may
be overly tight or their antagonist may be
disproportionately weak)
INJURIES
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Injuries occur when the muscle is overloaded
rapidly, during an eccentric contraction, when
it is fatigued, or when used over a long
duration
Just as you can identify people at risk for
heart disease, it is important to identify those
who are at risk for muscle or tendon strain
Considerations
Are the muscles recovered from
previous workouts?
Is there an existing injury that could be
aggravated?
Be aware of compensating for an injury
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Could make the athlete susceptible to
another injury or muscle imbalance
Is the athlete fatigued?
Controlling Momentum
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Muscles that are used to slow a
movement are at risk for injury because
they are contracted eccentrically
The tension of the contraction may not
be sufficient to withstand its attempt
Example: the hamstrings slowing the
hip flexion of a soccer or football kick
Lifting an Object
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The farther the mass is from the axis,
the greater the moment of inertia and
the greater the torque needed to cause
rotation
By positioning the object to be lifted
closer to the body, less torque is
required to perform the lift
FITNESS AND PERSONAL TRAINING
Biomechanical analyses can give
advice concerning:
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Positioning of joints to isolate specific
muscles
How to align the movement to the muscle
How to combine muscles for optimal results
Optimal speed
Best starting position and range of motion for
an exercise
How to modify the leverage to gain a greater
strength output
GAINING LEVERAGE
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You can use the lever systems to
modify exercises to make them more
challenging or to adjust the intensity
As the resistance moves closer to the
joint, the muscle will have an easier
time moving it
Moving the resistance further from the
joint (fulcrum) increases difficulty
Generating Tensile Force
Mechanics of muscle force generation are
dependent on the velocity of shortening as
well as muscle length
The tension of a musculare contraction is the
result of the attachment of crossbridges of
the myosin to the actin filaments within the
sarcomere
Tensile force is proportional to the number of
crossbridges ant the velocity of contraction
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Higher tension is developed at slower velocities of
shortening
Evaluating Resistance Machines
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An examination of equipment should
consider the following mechanical
issues:
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Type of lever
Axis of rotation
Path and range of motion
Machine resistance matching joint strength