SwimCents Vodcast, Peter Andrew and Michael Andrew's Two Cents on Swimming

Episode 9, Butterfly Macrocycle:

Microcycle 5 - Power-Phase Movement

In this episode Peter and Michael reviews & demonstrates the head position during propulsive phase of butterfly strokes, discuss acceleration and adduction stage of the pull, orientation, role of the upper arms.  Technique elements are demonstrated with SwimPro underwater camera footage of Michael.