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Stride length synergy when crossing obstacles found to be lower in Parkinson’s patients

Publicado em 08 abril 2021

A multidisciplinary research group affiliated with the Human Movement Laboratory (Movi-Lab) of the Department of Physical Education at São Paulo State University (UNESP) in Bauru, Brazil, measured the synergy of stride length in crossing obstacles in patients with Parkinson’s disease and concluded that it was 53% lower than in healthy volunteers of the same age and weight. Stride length is one of the main variables affected by the disease.

Synergy, defined as combined operation, in this case refers to the ability of the musculoskeletal system (or musculoskeletal system) to adjust movement when crossing an obstacle, combining factors such as speed and foot position, for example. Improving synergy in Parkinson?

7;s patients while walking can have a significant impact on their quality of life, as they fall, on average, three times more often than healthy people of the same age.

There are patients in our exercise group who drop three or four times a week. It is important to understand how these patients’ gait and locomotion adapt as they cross obstacles so that we can improve the synergy between steps. This approach allows us to refine the training protocol, improve locomotion, and try to reduce the frequency of falls. “

Fabio Augusto Barbieri, professor at the UNESP Physical Education Department and the Graduate Program in Movement Sciences

An article about the study will be published in the journal Gait & posture. Barbieri is the last author. The first author is the mechanical engineer Satyajit Ambike, professor in the Department of Health and Kinesiology at Purdue University in the USA. The study is the first to report impaired movement synergies in Parkinson’s patients.

“The innovation in our study is the focus on gait timing, or the rhythmicity, the consistency with which patients position their feet to maintain locomotion,” said Barbieri. “This can be assessed by measuring stride synergy. Synergy implies a goal and has to do with the way the musculoskeletal system adapts to achieve it. In our case, we looked at how the system adapts to achieve it to achieve the goal of crossing an obstacle while getting around. “

The researchers found that Parkinson’s patients are less able to adjust the position of their feet than healthy people when approaching and crossing an obstacle. “The musculoskeletal system always tries to adapt to maintain constancy while moving. Without this constancy, we can make mistakes that can lead to a fall,” said Barbieri. “People with Parkinson’s disease tend to have their feet positioned less consistently when walking, and as a result, gait timing tends to be unstable. Their speed increases and decreases as they walk, and stride length varies with the placement of the foot.”

Obstacles

13 Parkinson’s patients and 11 neurologically healthy control persons took part in the study. All participants were over 50 years old. To be eligible, they had to be able to walk unassisted, have normal vision and hearing (with or without lenses and hearing aids), have no orthopedic or neurological conditions other than Parkinson’s, and be able to understand and understand instructions follow. Patients were on Parkinson’s disease medication (levodopa) for at least three months prior to data collection.

Participants had to walk along a gangway (length 8.5 m, width 3.5 m) and cross a foam rubber obstacle (height 15 cm, width 60 cm, depth 5 cm) that was 4 m from the starting point. The walking speed was not fixed, but selected by each participant. No instructions were given as to which leg to cross the obstacle first, but its position was adjusted for each participant so that the right leg had to lead.

“We tried to standardize the task in such a way that all subjects crossed the obstacle with their right leg forward,” said Barbieri. “The idea was to make sure there weren’t any other factors affecting the movement pattern. The height of the obstacle was six inches as this is the standard curb height in Brazil. We thought it would be best to stick to the standard.”

A number of systems need to work together to create synergies to achieve a goal, he explained. “When the distance between the toes and the obstacle[[[[ before it is crossed ]and between the heel and the obstacle[[[[ after it’s crossed ]is very different, the risk of touching the obstacle increases. If you are too close to the obstacle before crossing it, you will need to lift your front leg high enough that it may prove impossible. If the trailing foot gets too close to the obstacle after crossing, the heel is likely to hit it, “he said, adding that ideally the gait timing should be constant and the foot not too close to the obstacle on either side should.

Biomechanics

The stride length synergy was measured using a methodology derived from mechanical engineering and adapted to the study of human movement. The method is not specific to gait analysis or Parkinson’s, but is based on a number of techniques that Ambike and Mark Latash of Pennsylvania State University use to measure upper extremity strength.

Eight motion capture cameras used in the study were purchased with funding from FAPESP (Grant No. 2017 / 19516-8). The study was also supported by a visiting research fellowship.

Twenty reflective markers were placed on the body of each participant in the experiment according to a specific gait analysis model. “As the subject approaches the obstacle along the gangway and crosses it, the cameras emit infrared light that is reflected by the markings. The cameras record the position of the markings and thus enable the step length and duration to be determined. Gait analysis software does the rest Calculations, “explained Barbieri.

According to Barbieri, the study was the first time this method was applied to gait analysis. “Another innovation was that we used a single variable to make possible gait timing-related inability to identify with relative ease, allowing for a more consistent future intervention to improve gait timing through exercise,” he said. “This is the point of gait analysis in general. You want to identify possible variables for gait changes and modify the intervention on that basis.”

The same researchers have since started a study to see if the height of the obstacle affects the synergy between the levels. “We want to know if this synergy changes because the obstacle is higher or lower. This affects the environment in which the patient is moving. If obstacles are at a certain height in the environment, they can cause problems and cause falls lead can change the environment to make locomotion easier, “said Barbieri.