Biomechanics and movement analysis
Biomechanics and movement analysis applies mechanical principles to technique. You should identify levers, planes and axes, explain force and motion, and evaluate stability or projectile flight.
Core concepts
- Levers: first class (fulcrum between load and effort, e.g. neck extension), second class (load between fulcrum and effort, e.g. calf raise), third class (effort between fulcrum and load, e.g. biceps curl). Most human levers are third class and favour speed and range over force.
- Planes and axes: sagittal plane with transverse axis for flexion/extension; frontal plane with sagittal axis for abduction/adduction; transverse plane with longitudinal axis for rotation.
- Newton's laws: inertia; acceleration proportional to force and inversely proportional to mass; action–reaction.
- Stability: increased by a larger base of support, lower centre of mass and a line of gravity falling within the base.
- Projectile motion: range depends on release speed, angle and height; air resistance modifies flight.
Worked example
In a biceps curl, the elbow is the fulcrum, the biceps provides effort and the forearm/hand provides the load. This is a third-class lever because the effort lies between the fulcrum and the load. The reasoning: locate the three points in order along the lever.
Traps
Swapping planes and axes; classifying a biceps curl as second class; assuming a longer lever always increases force; ignoring the effect of release height on projectile range.