KIN 240 – Introduction to kinesiology

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