Some biomechanical characteristics of standing up at three different speeds: implications for functional training

Individuals with motor disability typically stand up (STS) more slowly than able-bodied subjects, and are at risk of falling. The purpose of this study was to examine the effects of varying movement speed on angular displacement and velocity of trunk flexion at the hips and on extensor force production through the lower limbs. Able-bodied subjects were videotaped as they stood up at three different speeds (fast, slow, preferred) with feet on a force plate. Amplitude of hip flexion was greater but velocity was less when subjects moved slowly compared with fast. Moving slowly was also characterized by a decrease in peak support moment, an increase in time spent sustaining an overall extensor force of three times body weight, and a reversal in sequencing of joint movement onsets. The force-time trade-offs and variations in the basic motor pattern associated with differences in speed suggest that training to increase muscle strength and intersegmental coordination in STS should involve practising standing up at a range of speeds since the ability to control speed variation is critical to independence.