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23 Nov 2019

During a stress test of the cardiovascular system, a patient walks and runs on a treadmill. (a) Is the energy expended by the patient equivalent to the energy of walking and running on the ground? Explain. (b) What effect, if any, does tilting the treadmill upward have? Discuss.

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Deanna Hettinger
Deanna HettingerLv2
20 Mar 2019

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Related textbook solutions

Physics: Principles with Applications
7th Edition, 2013
Giancoli
ISBN: 9780321625922

Related questions

Several studies indicate that the elastic properties of tendons can change in response to exercise. In one study, guinea fowl were divided into a group that ran for 30 minutes a day on a treadmill, and a control group that was kept in their cages. After 12 weeks, the researchers measured the mechanical properties of the gastrocnemius tendon in each bird. The results for one control bird and one treadmill bird are shown in (Figure 1).

 

Part A

Treating the tendon as an ideal spring, what is the force constant for the control bird?

 

Part B

By how much does the control bird’s tendon need to be stretched in order to have the same amount of stored energy as the tendon of the treadmill bird at a deformation of 1.0 mm?

The Achilles tendon will stretch and then rebound, storing andreturning energy during a step. We can model this motion as that ofa mass on a spring. This is far from a perfect model, but it doesgive some insight. If a 60kg person stands on a low wall with herfull weight on the ball of one foot and the heel free to move, thestretch of the Achilles tendon will cause her center of gravity tolower by about 2.5mm.
A. What is the spring constant of her Achilles tendon?
B. If she bounces a little, what is her oscillation period?
C. When walking or running, the tendon spring begins to stretch asthe ball of the foot takes the weight of a stride, transformingkinetic energy into elastic potential energy. Ideally, the cycle ofthe motion will have advanced so that potential energy has justfinished being converted back to kinetic energy as the foot leavesthe ground. What fraction of an oscillation period should the timebetween landing and liftoff correspond to? Given the period youcalculated above, what is this time?
D. Sprinters running a short race keep their foot in contact withthe ground for about .10sec, some of which corresponds to the heelstrike and subsequent rolling forward of the foot. Given this, doesthe answer to part c make sense?

In chapter 10 we saw taht the achilles tendon will stretch and thenrebound storing and returning energy durint a step. We can modelthis motion as that of a mass on a spring. This is far from aperfect model but it does give some insight. If a 60kg personstands on a low wall with her full weight on the ball of one footand the heel free to move, the stretch of the achilles tendon willcause her center of gravity to lower by about 2.5mm
a) what is the spring constant of her achilles tendon
b) if she bounces a little, what is her oscillation period
c)when walking or running, the tendon spring begins to stretch asthe ball of the foot takes the weight of a stride, transformingkinetic energy into elastic potential energy. Ideally, the cycle ofthe motion will have advanced so that potential energy has justfinished being converted back to kinetic energy as the foot leavesthe ground. What fraction of an oscillation period should the timebetween landing and liftoff correspond to? Given the period youcalculated above what is this time?
d) Sprinters running a short race keep thier foot in contact withthe ground for about .1s some of which corresponds to the heelstrike and subsequent rolling forward of hte foot. Given this doesthe answer to part c make sense.

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