BIOMECHANICS OF HUMAN MOVEMENT
1. Biomechanics is the science concerned with the interrelationship of the biologic properties of the skeletal, articular, and neuromuscular systems and of the laws and principles of mechanics.
2. Biomechanics is concerned with both internal and external factors that affect movement of one's body,
as well as the movement of implements or other equipment used in exercise, sport, or other physical activity. Applications of biomechanics are seen in medicine, industry and the military, as well as in physical education and athletics.
3. Bones of the skeletal system that articulate at a joint serve as anatomic levers effecting movement upon application of force generated by skeletal muscle contraction.
4. Primary functions of skeletal muscle are affected by number, arrangement, length, and type of fibers. Some muscles are more powerful, while others permit greater endurance or range of movement.
5. Even relatively simple movements, e.g., walking, involve the action of numerous muscles in one or more of several roles to produce an efficient effort.
6. The somatic nervous system is involved with reception (afferent) and conduction (efferent) of neural impulses and ultimately, with the activity of skeletal muscle.
7. The basic functional structure of the neuromuscular system is the motor unit, which consists of a single motor nerve cell, together with its nerve fiber and the group of muscle fibers supplied by its branches. The strength of muscle contraction is dependent on how many motor units are activated by the central nervous system.
8. Dynamics is the aspect of mechanics in which motion of an object is brought about by unbalanced forces. There are two branches of dynamics: (a) kinematics, which deals with descriptive analysis of motion without consideration of forces causing motion; and (b) kinetics, which deals with the interrelationship of forces causing motion.
9. Kinematics includes the measurement of displacement, velocity, speed and acceleration in both linear and rotary (angular) motion about an axis.
10. Newton's three laws of motion addressing the concepts of inertia, acceleration, and action-reaction,provide an integrative understanding of forces affecting objects in motion, and are the cornerstone of kinetics.
11. Forces that modify motion include gravity, friction, momentum, impulse, and impact.
12. Statics is that aspect of mechanics, in which forces acting on an object are in equilibrium. Center of gravity and stability are concepts basic to static balance.
13. Torque, moment of inertia, angular velocity, and angular momentum provide analogues of Newton's three laws applicable to rotary motion. The work accomplished in rotary motion is dependent on the mechanical advantage of the lever system(s) employed.
14. In human physical performance, movements of one's body, as well as those of objects kicked, thrown, or caught, take place in a fluid environment, and are subject to the net propulsive force of drag and lift.
15. An increasingly wide variety of mechanical and electrical devices are being utilized to measure specific skeletal and neuromuscular interactions with mechanical factors affecting human movement.
16. The development of high-speed computers has provided the most important impetus for advances in bio- mechanics research. Some of this research has been successfully applied to effect improvements in perfor- mance and prevention of exercise and sports related injuries.
17. Principles of biomechanics are also applicable to movement entailed in daily living activities and many occupational tasks which, if employed properly, lead to reduced incidence of strain and injury, more effi- cient movement, and less fatigue.