- Discussion:
    - during swing, the ankle dorsiflexes by the concentric contraction of anterior tibialis muscle;
    - all other muscles are silent;
    - momentum generated by the gastrocsoleus and hip flexors at terminal stance carries the leg forward
    - during initial swing phase knee passively flexes and then knee passively extends at end of swing phase;
    - sub-talar joint assumes near neutral position, & toes dorsiflex slightly as foot prepares for next episode of stance;
    - once toe leaves the ground;
    - contraction of the quadriceps, initiated before toe off, apprarently serves two purposes;
           - it prevents heel from rising too high in a posterior direction;
           - it helps to initiate the forward swing of the leg;
    - during latter part of swing phase, slightly before heel strike:
    - hamstrings muscles become active;
           - function of the hamstring muscles at this time is to decelerate forward swing of leg and thereby control the position of the foot at heel strike