How Free Swimming Fosters the Locomotion of a Purely Oscillating Fish-like Body.

The recoil motions in free swimming, given by lateral and angular rigid motions due to the interaction with the surrounding water, are of great importance for a correct evaluation of both the forward locomotion speed and efficiency of a fish-like body. Their contribution is essential for calculating the actual movements of the body rear end whose prominent influence on the generation of the proper body deformation was established a long time ago. In particular, the recoil motions are found here to promote a dramatic improvement of the performance when damaged fishes, namely for a partial functionality of the tail or even for its complete loss, are considered.

Traumatic biceps femoris tendon subluxation in a young football player.

Snapping a knee related to a biceps femoris tendon subluxation is an uncommon syndrome that could be disabling in patients with high functional requirements such as athletes. We report a case of a 21-year-old soccer player with a painful left snapping biceps femoris tendon due to a varus trauma. He underwent knee arthroscopy and surgical exploration of the knee: the long head of the biceps femoris tendon was partially detached from his fibular insertion and there was a prominence on the fibular head.

The performance of a flapping foil for a self-propelled fishlike body.

Several fish species propel by oscillating the tail, while the remaining part of the body essentially contributes to the overall drag. Since in this case thrust and drag are in a way separable, most attention was focused on the study of propulsive efficiency for flapping foils under a prescribed stream. We claim here that the swimming performance should be evaluated, as for undulating fish whose drag and thrust are severely entangled, by turning to self-propelled locomotion to find the proper speed and the cost of transport for a given fishlike body.