Hip Angles and the Stepping Efficiency in Children
The creation of factual and dependable tests of the cardiorespiratory fitness for children is of importance for physical fitness and exercise professionals. As a result, a study was conducted to determine if VO2, oxygen consumption, while performing step aerobics in children is affected by altering the step platform height based on the length of the leg. Shahnawaz was one of the first to come to the conclusion that VO2 was associated to limb length and height-adjusted stepping exercise in adults. That conclusion led to the idea that perhaps the influence of leg length in stepping performance could be even greater in children. It was also thought that the modification of the step height and leg length might benefit young children in activities that use the bench for doing aerobic exercises (Francis et al. 337).
In the study, nineteen healthy, non-smoking, non-overweight children, ranging in age from 8 to 17 years old were used in the experiment. The following study was conducted to determine if VO2 of stepping in young children was affected by the step platform height based on leg length. As a result, the optimum platform height for stepping was determined (Francis et al. 338).
The height of the platform used in the test was based on the height of the subject’s foot when the hip was flexed at a given angle. First, the height of the foot when the hip was flexed (Hf), the femur length (h), and the angle of the hip (q) needed to be calculated. They were concluded from the geometric relationship of the subject’s stature and femur length as shown below.
From those connections, h was found to be Lf, the length of the femur for each age, times the stature (Ih) in centimeters. Thus, the platform height was found to be:
Hf = (Lf * Ih)(1- cosq)
The heights of the platforms were calculated from the above equation for hip angles of 65°, 73°, 83°, 90°, and 98°. To insure that the angles for stepping were correct, the hip angles of the subjects were measured with a goniometer. The subjects kept their backs flat next to a wall with the right hip flexed and the foot set on the platform with the heel of the foot even with the edge of the step (Francis et at. 339). The average of the hip angle for three measurements was used.
The subjects were allowed time between tests to allow for their heart rates to return to a resting level. Each of the subjects stepped for a five-minute period. The stepping procedure consisted of stepping up while fully extending both legs and stepping down with both legs to a set count. During the test, VO2 and HR were continuously measured (Francis et al. 340).
The results revealed that at the hip angle of 82°, the mean VO2 at each of the calculated hip angles was 30.46 ± 2.56 ml·kg-1·min-1 which was lower than the recorded values at the other hip angles. In the previous graph one can see that an 82° hip angle resulted in the lowest VO2 at the lowest point on the graph, and the hip angles of 65° and 98° represented the highest VO2 values. Similarly, at the optimum hip angle of 82°, the mean HR was 152.0 ± 15.9 beats per minute. The HR data was similar to that of VO2 with 82° resulting in the lowest point of the graph and 65° and 98° resulting in high HR values (Francis et al. 342).
All in all, the conclusion was that the VO2 and HR in children is greatly influenced by leg length, and that the stepping efficiency is at a maximum at a hip angle of 82°. The practical suggestions of this study reveal that the legitimacy of any kind of step test can be improved if bench height is related to the stature of a child rather than a fixed bench height. By determining an optimal hip angle, the development of an algorithm for a height-adjustable step test can be implemented to evaluate the cardiorespiratory fitness in healthy children (Francis et al. 345).
The Use of Geometry in Technological Advances
Geometry has also helped in the creation of new items that are supposed to reduce the medical problems a person may have. One new item, like the Body Geometry Saddle below, is a Y-shaped saddle for bicycles with the rear portion removed to reduce pressure on critical arteries. Many bike riders lean forward and, by not standing up while biking long distances, reduce blood flow to all parts of the body. Designed by Othopedic Seating Specialist Roger Minkow, M.D., the Body Geometry Saddle cushions and supports your “sit bones” while eliminating numbness and discomfort in pressure areas (Specialized 1). Today, many different forms of the Body Geometry Saddle, like the following, are being produced for different body shapes.
Along with new devices like the Body Geometry Saddle, new computer software, which uses geometry to help doctors, is also becoming increasingly popular.
Today computers play a big part in aiding surgeons. In the last couple of years, new technology has given doctors like Dr. Patrick J. Kelly at New York University Medical Center new ways of diagnosing and planning surgical procedures involving certain parts of the body (Junnarker 1). By looking at how computers can help surgeons, we see how computers are helping us enter a new century with a greater amount of medical excellence due to technology. Approved by the Food and Drug Administration, virtual-reality computer programs, like the Compass, can help surgeons glide through a patient’s brain past blood vessels and towards obstructions like a tumor, without harming any parts of the humans brain (Junnarker 2). The surgeon looks at a computer screen and sees a 3-D model of the patient’s brain, like in the following Compass pictures:
“Compass lets surgeons plan the safest, least invasive route to a tumor before the scalpel even touches the patient” (Junnarker 1). Computers are actually becoming cheaper and more powerful, and by using CT or CAT scans, computers can provide 3-D data on a Euclidean plane.
Computers can aid in indicating where a tumor end and blood vessels begin, which prevents damaging brain tissue. At Massachusetts Institute of Technology, Dr. Michael Feld uses spectroscopy (separation of light into primary color components to gather information about the light source) to detect colon cancer and heart disease (Junnarker 3). Gamma knife surgery also helps radiate tumors, but does not remove them from the brain. Most of these devices render 10 million triangulation’s per second. Triangulations are a method of dividing a three-dimensional surface into an extremely large number of triangles. These triangles are transformed onto the Euclidean plane, and the surface now appears three-dimensional on a computer screen. “Triangulation’s are the basic geometry used in calculating and rendering three-dimensional spaces” (Junnarker 5). Some virtual-reality medical software is even free for doctors over the Internet. The uses of virtual reality software are overall very effective and relatively inexpensive.
Geometry was also very useful for advances in the branch of science know as biomechanics. At the 1996 Summer Olympics, specialized high-speed cameras recorded the slightest movements of athletes in 10 different sports, aiming to perfect the intricate movements of an athlete. Coaches then use the data to help them win future events. Mont Hubbard of the University of California at Davis became the first engineer to trace the precise journey of a baseball from a pitcher’s hand to the catcher’s mitt (Tobin 1). Some coaches feel that athletes in some sports “may be approaching the limits of human potential,” so the smallest improvements carry great implications. Yet, the International Olympic Committee requires that these “photographers” must do their work without giving athletes any hint they are being studied. The photographers must “shoot” in silence and then study after the Olympics are over.
The cameras these researchers use shoot athletes from two or more angles at rates up to 200 frames per second (Tobin 2). For example, a tennis player serving may have four cameras attentive on the game--one following the player’s movement, two trained on the server, and one checking to see if the serves are in or not. This means that a 2-second serve will have 400 pictures of the server’s wrist, elbow, etc., and that around 4 to 5 million data points would be collected over the course of the Olympics (Tobin 2). These data points are converted into computerized human figures, whose movements are now viewed with exact precision in three dimensions. From these pictures, researchers hope to find the differences between men’s and women’s serves, especially in the areas where most injuries occur, the shoulder and elbows. They will use what they find and try to help young athletes moving up towards Olympic capability.
Geometry is used in many different medical professions. In treating joint problems, physical therapists use geometry in order to help relieve pain problems. Geometry is also used in studying the performance of different body parts, and through technological advances geometry has possibly even saved lives. The medical profession has improved greatly through the use of geometry.