Extremity speed represents the speed of movement of the end joints of the limbs (both wrists, ankles). Near the maximum value, the faster the speed of the extremities, near the minimum value, the less movement of the extremities. 

To find the local minima, we identify the ranges where the values reach a low point within the dataset. A local minimum is a point where the value is lower than its neighboring values. This indicates periods of less activity or reduced movement. The detection is based on a threshold percentage (e.g., 20% above the minimum value) to focus on the most significant dips. The output lists the frame ranges where these dips occur and their respective values.