Biomechanical analysis of forces and torques at the support lower extremity during two running-in-place exercises at three paces escrito por Muniz, Ana Elena, Ph.D., University of Maryland College Park, 1990, 377 páginas; AAT 9121394

Resumen

The purpose of this study was to compare the stress forces (SFs) and torques at the support lower extremity (SLE) between two running-in-place (RP) exercises at three paces. Also, two biomechanical analysis procedures were validated for their accuracy in estimating the forces and torques at the SLE. These parameters were estimated by using a 7-link model of the human body with Newtonian equations and either motion analysis or simulation procedures.

From the motion analysis procedures, the vertical estimated foot forces (EFFs) were excellent (Avg. r$\sp2$ = 98%, RRG = 5%), while the anteroposterior EFFs were inadequate representations (Avg. r$\sp2$ $<$ 67%, RRG $>$ 26%) of the ground reaction forces (GRFs). The stress forces (SFs) and torques were estimated with greater accuracy for the joints located closer to the support foot and for those in which the vertical force dominated.

The simulation procedures consisted of changing the period in the Fourier series of the moderate pace position data to correspond to the slow and fast paces, and by doing so, determine their kinematic parameters. The results obtained from the simulated forces and torques were less accurate than those from the estimated forces and torques.

The SFs and torques compared between the exercises were the maximum values during the support phase and the first.05 sec of landing. A 2 x 3 ANOVA with Repeated Factors was used to determine if differences existed. All GRFs, compressive forces, the landing proximal shear force at the shank, and the torque at the ankle were larger for RP thigh lift (RPTL) than for RP heel lift (RPHL) (p $<$.01). As the pace increased toward the fast tempo, all maximum shear forces decreased during both exercises (p $<$.05). Only during RPTL did the maximum proximal compressive force at the foot increase and the torque at the knee decrease as the pace increased toward the fast tempo (p $<$.05). The GRF and torque demands for this study ranged between walking and running.

The suggestions by Yessis (1984) of "harmful stress" experienced on the SLE during RPHL and not during RPTL cannot be supported. During RP exercises, the load on the SLE is of low magnitude; thus, injuries to the SLE musculoskeletal system probably result from a combination of high repetition and load bearing on the ball of the foot.

Índice (detalles del documento)

Director de tesis: Kelley, David L.

Universidad: University of Maryland College Park