A force-velocity relationship and coordination patterns in overarm throwing

Abstract

A force-velocity relationship in overarm throwing was determined using ball weights varying from 0.2 to 0.8 kg. Seven experienced handball players were filmed at 240 frames per second. Velocity of joints of the upper extremity and ball together with the force on the ball were derived from the data. A statistically significant negative relationship between force and maximal ball velocity, as well as between ball weight and maximal ball velocity was observed. Also, with increase of ball weight the total throwing movement time increased. No significant change in relative timing of the different joints was demonstrated, suggesting that the subjects did not change their "global "coordination pattern (kinematics) within the tested range of ball weights. A simple model revealed that 67% of ball velocity at ball release was explained by the summation of effects from the velocity of elbow extension and internal rotation of the shoulder. With regard to the upper extremity the internal rotation of the shoulder and elbow extension are two important contributors to the total ball velocity at release. Key PointsAn inverse relationship between load and velocity and a linear force-velocity exists in overarm throwing with ball weights varying from 0.2 to 0.8 kg.Qualitatively, no changes in coordination pattern (relative timing) occur with increasing ball weight within the tested range of ball weights.The absolute throwing movement time increased with ball weight.Quantitatively, with regard to the upper extremity, the internal rotation of the shoulder and elbow extension are two important contributors to the total ball velocity at release.

Keywords: Kinematics; ball weight; handball; proximal distal sequence.

Figure 1.

Experimental set-up. Subject at a 4-meter distance from the target drawn on a large mattress that avoids the balls bouncing back toward the subject.

Figure 2.

Relationship between ball weight and total throwing time (A) and release velocity (B) averaged over all subjects. Vertical bars indicate standard error of the mean (SEM).

Figure 3.

Relation between peak forces on the ball and release velocity of the ball Symbols indicate subjects; mean data are indicated by (□). Inset: all observations.

Figure 4.

A typical example of development of linear of the hip segment, ball, and angular velocity of the wrist (○), the elbow (◊) and ext/int rotation of the shoulder (□) in time before ball release (the symbols indicate different signals and not points of measurements).

Figure 5.

Relation between ball weight and maximal angular velocity of the flexion of the wrist (○), extension of the elbow (◊), and internal rotation of the shoulder (□), averaged over all subjects with SEM.

Figure 6.

Mean values and sem (n=7) of (A) absolute time before ball release and (B) relative time of the initiation of the internal rotation of the shoulder (□), elbow extension (◊) and wrist flexion (○) together with occurrence of the maximal angular velocity of the elbow extension (♦) and wrist flexion (●).