by BigMitch » Tue Feb 16, 2010 3:04 am
by Ze » Tue Feb 16, 2010 5:21 am
BigMitch wrote:This is how I got my number:
Sin = opposite/hypotenuse
(sin)x(hypotenuse) = opposite
[sin(15 degrees)] x [(5280 ft/mile) x (3 mile/hr)] = opposite
sin (15 degrees) = 0.2588
[0.2588] x [15,840 ft/hr] = opposite
4099 ft/hr = opposite
Therefore, 4099 ft/hr are climbed at 15 degrees at 3 mph.
Q.E.D.
by Ze » Tue Feb 16, 2010 5:27 am
by BigMitch » Wed Feb 17, 2010 2:38 am
by Day Hiker » Wed Feb 17, 2010 7:36 am
BigMitch wrote:Apparently, you have to measure the exact angle that your treadmill gives at a given setting.
http://en.allexperts.com/q/Advanced-Math-1363/Calculating-percent-incline-treadmill.htm
6A. The 'percent grade' incline is the ratio h/r as a percent. For example, if the belt is 50 inches long between the marks and the difference, h, is 2 inches, that is a 2/50 or 4% grade.
6B. The angle of inclination is arcsin(h/r)
by nhluhr » Wed Feb 17, 2010 6:58 pm
by nhluhr » Wed Feb 17, 2010 7:08 pm
by Day Hiker » Wed Feb 17, 2010 11:14 pm
nhluhr wrote:Keep in mind, step-mills are NOT the same as actual steps because you're only pushing against a moving step to support your weight instead of actually lifting your weight with each step. The work you do will be drastically lower per step on a mill than on actual stairs.
by MoapaPk » Wed Feb 17, 2010 11:57 pm
by nhluhr » Fri Feb 19, 2010 4:12 am
Perhaps you need a little less simple physics. The difference is equal to the potential energy gained by the change in height and is quite significant (approx 0.6 kcal per flight of stairs for an average man). Not to mention the additional benefit of core-stabilizing exercise that you get from actual motion.Day Hiker wrote:nhluhr wrote:Keep in mind, step-mills are NOT the same as actual steps because you're only pushing against a moving step to support your weight instead of actually lifting your weight with each step. The work you do will be drastically lower per step on a mill than on actual stairs.
Hmmm. This is incorrect. There is no difference, unless you are holding the handrail. Simple physics dictates that pushing down on stationary stairs as your body goes up is identical to pushing down on moving stairs as your body remains stationary (except for the negligible amount of air friction on your traveling body in the former case). In either case, the forces of your feet on the steps and the total work performed are the same.
by Ze » Fri Feb 19, 2010 5:55 am
nhluhr wrote:Perhaps you need a little less simple physics. The difference is equal to the potential energy gained by the change in height and is quite significant (approx 0.6 kcal per flight of stairs for an average man). Not to mention the additional benefit of core-stabilizing exercise that you get from actual motion.
by nhluhr » Fri Feb 19, 2010 7:14 pm
Arbitrarily changing a frame of reference does not allow you to ignore the change in potential energy... which I specified above. This is the simplest of physics: PE gained = weight * height gained. If you don't go UP you're not doing that work to store PE.Ze wrote:nhluhr wrote:Perhaps you need a little less simple physics. The difference is equal to the potential energy gained by the change in height and is quite significant (approx 0.6 kcal per flight of stairs for an average man). Not to mention the additional benefit of core-stabilizing exercise that you get from actual motion.
Day Hiker is correct. You have to switch the reference frame to that of the moving stairs. Relative to the stairs, the person is moving up. Also, gravity (potential energy) is still acting on the person. And whatever stabilization, since there is still the same relative motion between person and stairs.
by drjohnso1182 » Fri Feb 19, 2010 8:23 pm
nhluhr wrote:Arbitrarily changing a frame of reference does not allow you to ignore the change in potential energy... which I specified above. This is the simplest of physics: PE gained = weight * height gained. If you don't go UP you're not doing that work to store PE.Ze wrote:nhluhr wrote:Perhaps you need a little less simple physics. The difference is equal to the potential energy gained by the change in height and is quite significant (approx 0.6 kcal per flight of stairs for an average man). Not to mention the additional benefit of core-stabilizing exercise that you get from actual motion.
Day Hiker is correct. You have to switch the reference frame to that of the moving stairs. Relative to the stairs, the person is moving up. Also, gravity (potential energy) is still acting on the person. And whatever stabilization, since there is still the same relative motion between person and stairs.
Yes, you still have resistance and yes it is pretty close to actual, but it's NOT EQUAL and the difference in work output can be offset if you just use the stepmill at a faster rate but on a per-step basis, each step of a stepmill is less work performed than an actual step, not that it matters for the guy who started the thread, because he has actual flights of stairs to climb.
by nhluhr » Fri Feb 19, 2010 10:35 pm
Well, you don't have to agree with me.... but if you for instance looked up a calorie counter that shows stairclimbing machines vs walking up stairs, you'd see the difference is around 20%...drjohnso1182 wrote:Day Hiker's right. Determining where the energy goes is left as an exercise for the reader.
On topic, I agree with the experiences of those earlier who said that stair-climbing is a good workout but rough on the knees. It's also really boring, so try to convince some friends to work out with you; misery loves company and all that.
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