Walking people have to adjust their gait again and again to walk on the curb or steps, intentionally or unintentionally, and each person has developed control strategies to control muscle activity in order to respond to changes occurring in the outside world, thereby protecting them from Effects of trip and fall accidents.
researchers at the University of Bayreuth have now analyzed these strategies and their effectiveness using computer simulations. They were able to show that a strategy based on visual perception, which anticipates and prepares muscles for height differences at an early stage, protects walking posture better than situational muscle reflexes. Their findings were published in Scientific Reports.
Neuromuscular model of walking on uneven ground. Anticipatory adjustments in the leg muscles can adjust the body's center of mass (CoM) even before changes in the ground surface.
If curbs, steps, or other differences in ground height are sensed in advance, the muscles can adjust accordingly. The knees and ankle joints are more bent, and the height of the body's center of gravity changes. This anticipatory muscle adaptation is called an anticipatory control strategy or "advanced strategy" in research. Another less demanding "low-level strategy" is based entirely on muscle reflexes. These reflexes are only triggered when taking a step from the curb or stairs during walking, and the risk of tripping and falling is imminent.
"In our study we tried to discover the impact of these different strategies on gait behavior and their importance for safely overcoming height differences. However, the problem arises that we can never completely switch off these two control strategies as in humans Either way. It is therefore difficult to determine the effect of a single strategy on selected test subjects. However, with computer simulations such an analysis is possible," explains PD Dr. Roy Müller, who led the study. Research Assistant to the Chair of Exercise Science and as Head of the Gait Laboratory at the University of Bayreuth and Klinikum Bayreuth GmbH-Medizincampus Oberfranken.
The researchers based their computer simulation on a neuromuscular model, in which the muscles are stimulated only by reflexes. Using this model, the effects of low-level strategies can be shown in isolation. It turns out that this strategy guarantees an effective, accident-preventing adaptation for walking onto a suddenly lowered surface only if the height difference does not exceed 3 cm. However, curbs are usually 5 to 12 centimeters high. Clearly, reflex-based control strategies alone are not sufficient to avoid falls.
Therefore, as part of the research, additional anticipatory strategies were added to the model. Computer simulations show clear benefits. The strategy of combining high and low ensures that height differences from 3 to 21 cm can be managed without incident. "This result clearly highlights the importance of anticipatory adaptation in daily life. It demonstrates that people who can only adapt to a limited extent due to vision loss or neuronal disease are at a much higher risk of falling," Mu said. Le said.
Following this new study, the Bayreuth research team wants to further investigate prospective strategies. This includes, for example, the possible effects of drugs or alcohol, which may impair muscle control. Further investigation will focus on the question to what extent high-level strategies can be enhanced and optimized through training and learning programmes.
