They do this by flexing (standing up, bending backwards). This is accomplished by leaving unbonded the areas where flexing or bending is to occur. Kirk flexing his muscles in a pose, and a large crucifix. Dragonfly wings behave highly dynamically during flight, flexing and twisting during each beat. Pain can also be reproduced by flexing the arm against resistance. The steel plate prevents the foot from flexing during hard landings when parachuting. These savings are realized because less energy is wasted flexing fewer tire sidewalls. Simply flexing the wrist to 90 degrees will decrease the size of the canal. Most spurs are activated by the rider flexing the heel slightly up and in. This tidal flexing heats the moons' interiors by friction. Turfing incorporates other dance style concepts such as tutting, flexing, waving and animation. Flexing, substituting and table rotating rails have all been used. Suppose the wire changes its shape with time, by flexing. Furthermore, with the bayonet fitted excessive flexing became an issue. The flexing of the frame interacts with the suspension.