The metabolic cost of walking is determined by many mechanical tasks, but the individual contribution of each task remains un-clear. We hypothesized that the force generated to support body weight and the work performed to redirect and accelerate body mass each individually incur a significant metabolic cost during normal walking. To test our hypothesis, we measured changes in metabo-lic rate in response to combinations of simulated reduced gravity and added loading. We found that reducing body weight by simula-ting reduced gravity modestly decreased net metabolic rate. By calculating the metabolic cost per Newton of reduced body weight, we deduced that generating force to support body weight comprises
28% of the metabolic cost of normal walking. Similar to previous loading studies, we found that adding both weight and mass increased net metabolic rate in more than direct proportion to load. How-ever, when we added mass alone by using a combination of simulated reduced gravity and added load, net metabolic rate increased about one-half as much as when we added both weight and mass. By calculating the cost per kilogram of added mass, we deduced that the work performed on the center of mass comprises
45% of the metabolic cost of normal walking. Our findings support the hypothe-sis that force and work each incur a significant metabolic cost. Specifically, the cost of performing work to redirect and accele-rate the center of mass is almost twice as great as the cost of generating force to support body weight.

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Active-response golf shoes are disclosed. The golf shoes include at least one sensor, a controller, and at least one active-response element. The sensor and controller operate to rapidly determine if a golfer is walking or swinging a golf club. Once this determination is made the controller and active-response element rapidly change the shoe’s characteristics. If the controller determines that the golfer is walking, the shoe provides a soft and flexible walking platform. If the controller determines that the golfer is swinging, the shoe morphs or changes automatically to provide a stable hitting platform. The controller senses various predetermined conditions such as pressure under the ball of the user’s foot to determine whether the golfer is walking or swinging. The active-response elements may be a sole adjuster, a lace adjuster, and/or an upper adjuster. Methods of determining the golfer’s type of movement are also disclosed.

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When I joined the Marine Corps, I wore a helmet, flak jacket, two canteens with cup, and a first aid kit. I had two magazine pouches that held six rifle magazines, and I could carry two fragmentation grenades on each of the magazine pouches. That was the extent of my load. In the mid-1990s, we hit a technological explosion and are still being buried by great combat gear. Today I wear a different helmet, an interceptor vest with small arms protective inserts, and have really increased what I carry, quadrupled what I have to be able to do, and decreased tenfold the amount of time that I have to learn all of my required skills. On 24 May 2004, there was an article in the Marine Times discussing hot new gear proposed by the Marine Corps Warfighting Laboratory (MCWL). This article identified even more gear to come the infantryman’s way. This is not a ridiculous thought either. These are mission essential equipment identified over years of actual missions and detailed analysis. Without delving into the training time required just for the equipment additions, we should seriously consider the combat load of the individual. In 2001, the Infantry Operational Advisory Group recommended key weights during different times of movement toward the enemy. But based on actual experiences, there is no reasonable way to follow these combat load guidelines. The answer to our increasing dilemma of combat load may have been identified in Robert A. Heinlein’s book Starship Troopers. In the story, one man had a strength-enhancing exoskeleton suit that protected him from the environment, to include chemical or biological worries. It allowed the wearer to jump over buildings and run across countrysides faster than today’s vehicles. There were built-in communications, optics, protection, and strength. In many ways Heinlein’s projection has been accurate. What we have not done is attacked the basic problem of the equipment load that he has to carry. This may be about to change.

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