Posture and movement control of young and elderly sedentary individuals and runners

Abstract

The broader goal of this project is to investigate posture and movement control of young and elderly sedentary and runners individuals. Our previous research on posture control showed by the first time that, in comparison to young adults, elderly individuals produce fewer postural changes while standing in an unconstrained way (a task similar to our natural posture we adopted day by day). More specifically, we found that elderly individuals present a deficit in the load/unload strategy typically employed for the posture maintenance during unconstrained standing. However, the causes of this deficit are still unknown. Our hypothesis is that postural changes are triggered by sensory information which indicates pain or discomfort and the decrease of the somatosensory information in the elderly individuals would then be responsible for the observed deficit in posture control. By testing this hypothesis, we expect to show that sensory information has an important role in the production of postural changes. In another study we conducted about elderly runners, the main observed difference by the first time was that elderly individuals present greater foot abduction (toe-out) during running than young adults. This alteration has been observed in elderly individuals in general during walking, and identified as a protective mechanism to not overload the medial compartment of the knee joint. It is also known that elderly individuals present a different joint torque distribution in the lower limbs during walking in comparison with young adults. However, it's not known the relation between the movement patterns, particularly the foot abduction pattern, and the mechanical load on the knee joint during running by elderly individuals and neither the longitudinal effect of running practice on this relation and on the mechanical joint load distribution. Another unknown aspect is the actual effect of the running practice on the posture control of elderly individuals. With this project, we want to understand why elderly individuals change their movement pattern during running, to determine for the same subjects if this altered pattern is also present during walking and standing, and to determine the effect of running practice on the elderly posture control. Our hypotheses are that the strategy of greater foot abduction is present in all movement tasks and that the use of this strategy is related to the integrity of the knee joint, even considering the highly active elderly individuals and that the practice of running contributes for a better postural control in this population. These findings will contribute for a greater understanding of the benefits of the practice of running and the adaptations developed by the elderly runners and in this way to contribute for the prescription of this activity to the elderly population. To answer these questions , we will: 1. Investigate the relation between sensory information, postural changes, and foot plantar pressure during unconstrained standing in elderly and young adults; 2. Investigate the effect of regular practice of long distance running on the postural control of elderly individuals; 3. Investigate the mechanical load on the lower limb joints during walking and running and relate these loads with foot abduction angle in elderly individuals in comparison to young adults; and 4. Investigate the effect of regular practice of long distance running on the joint mechanical load and its distribution during walking and running by elderly individual in comparison to young adults. For such, we will conduct three experiments. One of the experiments has a longitudinal design where elderly individuals will be trained in running for about 10 months. As a whole, these findings will contribute for a greater understanding of the posture and movement control of sedentary and physically active elderly individuals. We expect to produce at least four articles in scientific journals to divulgate these results. (AU)