Introduction to Sports Biomechanics: Analysing Human Movement ...

Local minimums
A turning point such as A, C and E in Figure 3.22 is known as a ‘local minimum’, for
which two conditions are necessary:
The angle at that point must be less than its value at any nearby point; it is not
necessarily the overall or ‘global minimum’ value, hence the use of the term ‘local’.
The gradient of the angle curve, the angular velocity, must change from a negative
value (when the angle is decreasing) to a positive value (when the angle is increasing);
hence, the angular acceleration is positive.
For an angle–time graph, the above can be summarised as follows: a local minimum
angle (A, C or E) corresponds to a condition of zero angular velocity – changing from a
negative to a positive value – and a positive acceleration.
Local maximums
MORE ON MOVEMENT PATTERNS – THE GEOMETRY OF MOTION
Figure 3.22 Variation of knee angle with time in treadmill running; further explanation of angle–time patterns.
A turning point such as B and D in Figure 3.22 is known as a ‘local maximum’, for
which two conditions are necessary:
The angle at that point must be greater than its value at any nearby point.
The gradient of the angle curve, the angular velocity, must change from a positive to
a negative value; hence the angular acceleration is negative.
For an angle–time graph, a local maximum angle (B or D) again corresponds to a
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