1. Applications in Biomechanics

2. Goals of applied biomechanics:
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

3. Continued….
3. Fitness and Personal Training: biomechanical analysis can be applied to both exercise and exercise equipment

4. Overview…. Performance Improvement:
Application 1 – The Pre-Stretch
Application 2 – Training: Plyometrics
Application 3 – Equipment Design
Injury Prevention & Rehabilitation:
Application 4 – Injury Risk Assessment
Application 5 – Controlling Momentum
Application 6 – Lifting an Object
Fitness & Personal Training:
Application 7 – Gaining Leverage
Application 8 – Generating Tensile Force
Application 9 – Evaluating Resistance Machines

5. PERFORMANCE IMPROVEMENT
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 the desired action

6. 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
Think elastic recoil of a stretched rubber band

7. Performance Improvement
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 pre-stretch, the action can be more effective (harder slap shot, tennis serve, etc)

8. TRAINING: PLYOMETRICS
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

9. Training: Plyometrics
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

10. Equipment Design Example: golf
Golf clubs have changed a lot over the years
Materials used, length of the club's shaft, etc.
Athletes must accommodate the changes in equipment in order to benefit from them

11. INJURY PREVENTION – INJURY RISK ASSESSMENT
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)

12. INJURIES
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

13. Considerations Are the muscles recovered from previous workouts?
Is there an existing injury that could be aggravated?
Be aware of compensating for an injury
Could make the athlete susceptible to another injury or muscle imbalance
Is the athlete fatigued?

14. Controlling Momentum
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

15. Lifting an Object
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

16. FITNESS AND PERSONAL TRAINING
Biomechanical analyses can give advice concerning:
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

17. GAINING LEVERAGE
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

18. 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
Higher tension is developed at slower velocities of shortening

19. Evaluating Resistance Machines
An examination of equipment should consider the following mechanical issues:
Type of lever
Axis of rotation
Path and range of motion
Machine resistance matching joint strength