Figure 2.

A proposed performance-based index of muscle power. (A–D) The Muscle Quality Index (MQI) is a performance-based functional assessment involving ten repetitions of the sit-to-stand maneuver performed as rapidly as possible. The test requires the use of a scale to record body mass (A), a tape measure to obtain leg length (B), along with a stopwatch and chair and for the timed functional task (C,D). The MQI score is calculated using the following equation: ((leg length × 0.4) × body mass × gravity × 10)/sit-to-stand time.