Figure 1

Level 2 of the exercise progression as per the description in the text. The heel slides along the table until the right knee is fully extended. Electronic switches are located on the right foot [B] which contacts with the metal plate located on the table [A] and the right thigh [C] which contacts with the wooden frame [D] to identify temporal events so that the motion may be divided into distinct phases. The total exercise was from foot off the bed to foot back on the bed. For levels 2 and 3, the knee extension phase was from knee off the wooden frame to knee back on the wooden frame.