Fig. 10.

Velocity profiles of simulated movements.A, The thick solid line gives the tangential velocity of the bend point generated in a passive arm by pulling with a weight of 11 gm (see Materials and Methods). This velocity profile is compared with the simulated velocity profiles of the arm pulled by the fixed gravity force. The thin solid line represents the solution where the drag forces are excluded. The dashed line gives the solution where the drag coefficient (C_D) is set to 0.313. This value of C_D gives the best fit (minimal mean square difference) to the velocity profile measured from the passive arm. This C_D value was used to simulate the reaching movements where the pulling forceF_muscle was proportional to the cross-section area of the arm at the bend point. The results are shown in B. The thick lines give the velocity profiles obtained for different initial force (F_ini). The thin linesbranching from each curve are the velocity profiles whereF_muscle is set to zero when the bend point has traveled >70% of the length of the arm.