1. KIN 240 – Introduction to kinesiology
Biomechanics of Physical Activity

2. What is biomechanics?
Biomechanics is the application of mechanical laws of physics and engineering to motion, structure and function of all living systems
Structure refers to anatomy while function refers to being able to accomplish a specific purpose
How do we produce forces to generate movement?
How do forces (e.g. – gravity) affect the functioning of body tissues?
How do forces affect the structure of our body?

3. What do biomechanists do?
Biomechanics researcher
Perform experiments on problems of interest and/or assist with product development
Footwear design, equipment design
Clinical biomechanist
Perform biomechanical analyses in medical settings to guide care for patients
Gait analysis in cerebral palsy patients to determine if surgery warranted and/or to prescribe physical therapy techniques
Performance enhancement specialist
Analysis of techniques to improve performance and/or prevent and identify injury mechanisms
Usually associated with elite/professional athletes

4. What do biomechanists do?
Ergonomist
Experts at improving efficiency and safety of employees
Design of tools, job sites, task and/or behavior modifications
College/university professor
Teach biomechanics related courses in Kinesiology, Engineering and/or Medicine
Conduct research on biomechanics issues
Orthotist/prosthetist
Use biomechanical concepts to design/fit custom devices to support injuries and medical conditions
Development of prosthetic devices secondary to amputation

5. Goals of biomechanics
To understand how people use and are affected by the fundamental principles of mechanical physics and engineering that explain how forces influence our structure and function
What factors influence the composition and strength of damaged ligamentous tissue?
To apply theoretical understanding gained through attainment of first goal to determine how best to
Improve performance effectiveness (function)
How to improve jumping movements?
Increase safety and health of those body tissues that are affected by forces or those tissues involved in physical activity (structure)
How to prevent baseball pitching injuries?

6. History of biomechanics
Early beginnings
Aristotle investigated biomechanical questions when analyzing animal motion and human walking pattern in 300’s BC
DaVinci credited with developing first systematic examination of mechanical principles of human and animal movement (15th & 16th centuries)
Industrial revolution in early 20th century provided inventions such as cameras to measure movements
1920’s saw investigation of efficiency of human movement in sport and industrial settings
Post-WWI (and later WWII) used biomechanics to design prosthetics for war veterans who lost limbs
1950’s saw study of anthropometry (study of physical dimensions of people) as it related to auto, space and transportation industries
Design of seats, instrument panels, etc.

7. History of biomechanics
Contemporary biomechanics
Creation of professional organizations and graduate-level university programs developed in 1960’s
Rapid growth in field of biomechanics in 1970’s
American Society of Biomechanics
International Society of Biomechanics
Current university programs not only offer biomechanics courses but also undergraduate and graduate specializations in kinesiology, allied health and or engineering departments

8. Research methods in biomechanics
A model for analysis – allows researchers to design experiments and practitioners to apply knowledge from research
Step 1 – identify your question
Step 2 – state performance goal/s
Step 3 – consider influencing factors
Step 4 – understand motions and mechanics
Step 5 – determine relevant biomechanical principles and movement techniques
Step 6 – observe or measure
Step 7 – assessment, evaluation and interpretation

9. Research methods in biomechanics
Biomechanical instrumentation and tools
Motion measurement devices
High-speed digital cameras and other motion detection technology
Can be used to track motion of body segments using reflective markers and/or LEDs – can determine positions, velocities, acceleration/deceleration
Golf swing analysis, etc.
Force measurement devices
Force transducers can be attached to (humans) or implanted in (animals) body to measure forces exerted on body causing motion and/or injury
Force platform/plate measure ground reaction forces for gait analysis to determine appropriate footwear and/or orthotics
Electromyography (EMG) used to estimate muscle forces using surface electrodes to measure electrical activity in contracting muscles

10. Overview of knowledge How do external forces act on performers?
Gravity pulls us toward earth – force of gravity = weight
Ground reaction force generated any time you push against the ground (action) because the ground pushes back (reaction)
Can be created in any direction – without GRF, you can’t go anywhere – you must push against the ground so that it can move you in opposite direction
Friction is force needed to make sure individual doesn’t slip when ground pushes back
Air/fluid forces produce resistance (force) to movement too – greater speed of movement increases resistance

11. Overview of knowledge How do internal forces act on performers?
Tissue biomechanists study internal forces acting on body to understand mechanisms of injury and/or how to increase force production by muscles and tendons
Compressive loading pushes tissues together
Significantly greater GRF when landing from jump vs. walking
Shear loading causes tissues to slide against another tissues
Abrasive skin injuries
Tensile loading pulls tissues apart
Arm motion with overhead throw wants to pull shoulder joint apart and imparts huge load to muscles, tendons, ligament & joint capsules of the shoulder complex

12. Overview of knowledge Assessment and evaluation of performers
Performance assessment in physical activities
Investigate biomechanics of elite/highly skilled athletes to determine optimal techniques for performance
Use those techniques to improve performance in novice/less skilled individuals to ensure optimal outcome
Due to individuals differences, unreasonable to expect that techniques for given movement identical for people of all shapes, sizes, strengths and antomical variations
Clinical assessment
Investigate biomechanical values of general population to identify normative data
Can help identify dysfunctional movement and/or whether or not rehabilitation intervention has been successful