Research on treadmill and overground walking
Lauren Powell's Blog
Posted by Lauren Powell April 12, 2013
Here's an interesting research:
Eight subjects in a very good health (2 male, 6 female; age: 30.679.9 yr) provided informed consent prior to data collection in this study approved by the institutional review boards of the University of Texas at Austin and University of Florida.
An instrumented split belt treadmill with the treadmill surface even with the laboratory floor was used to record GRFs for both the treadmill and overground (i.e., the belt-speed was set at zero) walking trials. The sole f80 treadmill was placed in the center of a 12-camera motion capture (Vicon Motions Systems Ltd, Oxford, UK) viewing volume. The treadmill consisted of two side-by-side belt surfaces with sensors that independently measured the 3D forces and moments applied by each foot at 2000 Hz. Reflective markers were placed on each heel and the sacrum, and their 3D positions were recorded at 100 Hz.
Subjects first walked overground at their self-selected speed for ten trials. Data for each trial included the steps immediately previous to and following contact with the belt surface acting as a force plate. The large belt surface allowed recording of at least one stance phase and avoided force plate targeting. The leg (right or left) that made a good force plate contact during the initial trial was then selected (target leg) and used for all subsequent trials of that subject (so that subjects could keep speed consistent by starting in the same position in each trial). Gait cycles were defined from ground contact to ground contact of the same leg, with the GRF record determining most contacts. Markers placed on the heel were used to calculate ground contact when the foot did not contact the force plate. For the gait cycle associated with each complete stance phase on the force plate, we calculated velocity from the average velocity of the sacrum marker and cadence from the inverse of the stride time. The mean and standard deviation of the velocity were calculated for each combination of
five strides, with the mean of the five trials with the lowest standard deviation used as the treadmill speed. The overground cadence was then calculated from the same trials, and a metronome was used to control the cadence for the treadmill trials. Three walking trials were conducted on the treadmill, each lasting 30 s, which resulted in 16–20 gait cycles per trial, depending on individual stride length. The five strides whose mean walking speed most closely matched the overground mean were then selected for analysis between conditions. This allowed us to carefully match speed and cadence between conditions, since A/P GRFs are extremely sensitive to these variables.
3. Data analysis
The GRF data were low-pass filtered at 20 Hz using a fourth order Butterworth filter. The peak braking and propulsive GRFs and the total braking and propulsive impulses (i.e., time integral of the negative and positive A/P GRF, respectively) associated with each of the five strides were calculated and averaged for each subject and condition. The Shapiro–Wilk test was used to test the null hypothesis that the data were normally distributed. Since this null hypothesis was not rejected, a twosided paired t-test was used to identify differences between conditions.
There were subtle, but significant, differences observed in the peak GRFs between treadmill and overground walking, even though no significant differences were found in walking speed (1.5770.15 vs. 1.5670.19 m/s, p ¼ 0.83) or cadence (117.478.3 vs. 117.177.4 step/min, p ¼ 0.75) between conditions. The peak negative and positive horizontal GRFs in early and late stance, respectively (Fig. 1), were reduced by less than 5% BW during treadmill walking compared to overground walking. The magnitude of the braking impulse was also slightly less during treadmill walking, but there was no significant difference between the propulsion impulses.
Posted March 28, 2013
About my family
I have older and younger sister. My older’s sister name is Renata and she is 34 years old. She lives with my father’s first wife in their family house in Prague. She studies law at the university and also works at my father’s law office. My sister has got boyfriend for four years and I am sure they will later get marry. They both have similar hobbies, they like children. Every summer they go for three weeks for a camp with their friends and they look after children and play games, make trips with them. They like exhibitions and films. They also like travelling so they travel across US.
My younger sister is 23 and her name is Lisa. She lives with me and mum and she studies hotel school, which she enjoys a lot. She is the most vivid from us – three sisters. Many people say she is alike me. Some says she would look like me if she got a short hair and blue eyes. Sometimes people think we are twins. She is very social, she hasn’t problems with meeting anybody and so she has many friends. She hates history and physiscs, she likes practical subjects, she is very handy. The best what can be for her is being on our cottage with her friends.
Daily life of my family is very hectic, so we meet only in the evening. In the morning my sister has go to school very early in the morning, than leaves my mother and i am the last one who leaves our flat. I am at school and in the afternoon i am mostly first one who comes home. Except days when i am lerning drive a car or i have a math lesson in the afternoon. The last one who comes is my mother. So we meet us only in the evenings by the dinner. On weekends go my mother and sister on our cottage in Ceský ráj and i usually stay in Prague with my boyfriend. When me and my sisters were younger we also spent some weekend with our father, but he ahs to travel a lot and now we are older and have our own plans for weekend so we meet with him every Thursday evening and we go for a dinner.
My best friend is my class-mate. Her name is Klara and she is 18 years old. She is thin a smaller than me. She has brown and little bit curly hair, green and brown eyes and beautiful white skin. She is very clever, inteligent, generous, hard-working, jokeful. But she is also sometimes moody, shy and depressed. She can be very angry, if something isn’t fair, she can as angry as i sometimes can’t believe what in her is. She sometimes seemed she has no self-confidence. She understands my problems, she is very helpful.
She is very interesting girl. I know none of girls who can ride a morobike. She loves animals, she has also two dogs. She likes same music as me, she likes reading books and good films. But she has got quite strict parents, so she can’t go very often in the evening out: to the cinema, or some club.
More info with updates will be available soon...