Design and Validation of a Device Attached to a Conventional Bicycle to Measure the Three-Dimensional Forces Applied to a Pedal.

Knowledge of the forces applied to the pedals during cycling is of great importance both from the point of view of improving sporting performance and medical analysis of injuries. The most common equipment for measuring pedal forces is usually limited to the study of forces in the sagittal plane. Equipment that measures three-dimensional forces tends to be bulky and to be incorporated into bicycles that are modified to accommodate it, which can cause the measurements taken to differ from those obtained in real pedalling conditions. This work presents a device for measuring the 3D forces applied to the pedal, attachable to a conventional bicycle and pedals, which does not alter the natural pedalling of cyclists. The equipment consists of four gauges located on the pedal axis and two on the crank, controlled by a microcontroller. Pedal forces measurements were made for six cyclists, with results similar to those shown in the literature. The correct estimation of the lateral-medial direction force is of great interest when evaluating a possible overload at the joints; it will also allow a comparison of the effectiveness index during pedalling, showing the role of this component in this index from a mechanical standpoint.

[Metabolic changes in brain cortex related with the strabismus treatment. Preliminary results with SPECT]. / Cambios metabólicos en la corteza cerebral relacionados con el tratamiento de estrabismo. Resultados preliminares con SPECT.

OBJECTIVE: Our aim was to demonstrate metabolic changes occurring in brain cortex during strabismus treatment. MATERIAL AND METHODS: Single photon emission computed tomography (SPECT) of brain was made in patient with strabismus. The study only included congenital esotropia and excluded patients with other anomalies. Strabismus treatment was carried out with botulinum toxin or surgery. Brain SPECT was done prior to and after treatment. Changes were analyzed and related with strabismus response. RESULTS: We studied three children with congenital and variable esotropia for a total of three cases. In Case 1, basal SPECT showed hypoperfusion in left frontal lobe (7.38). Response to botulinum toxin was good for correcting strabismus and obtaining binocularity from third month. Control SPECT showed correction of perfusion of frontal lobe (-1.19). With Case 2, we observed hypoactivity in left parietal area (8.59); after botulinum treatment, strabismus was corrected and binocularity was demonstrated, while control SPECT showed increase of hypoactivity levels (5.95). Finally, in Case 3, strabismus was corrected at surgery with binocularity. Basal SPECT demonstrated very important hypoactivity in right hemisphere, especially in areas 3, 4, and 5 areas (-0.7, -3.71, and -11.09, respectively); in addition, positive changes after treatment were demonstrated (9.78, 6.44, and 3.22, respectively). CONCLUSIONS: Metabolic changes in brain cortex took place in congenital esotropia with SPECT. In all cases, brain SPECT could demonstrate changes after treatment with improvement of different areas, and good response of motor and sensorial state. This apparently is the first report concerning metabolic changes of brain cortex related with strabismus under treatment, and demonstrates the importance of brain cortex in genesis, evolution, and stability of visual functions and with regard to the failure of these in patients with strabismus.