I guess the question
of safety has to be an important one, especially since every book on exercise
has one or two chapters on injury, everything from dog bites to shin splints.
This is probably what prompted Craig McQueen, M.D., to ask A. W. Daniels, Ph.D.,
Adjunct Professor, Material Science and Engineering and Orthopedic Surgery of
the University of Utah to analyze the comparison of the impact loads transmitted
by rebounding and more conventional exercise surfaces.
In
this report, they compared rebounding to jogging. Briefly,they accomplished
the following:
Determined the
approximate spring constant of the rebounder by measuring the deflection of
the surface when various persons of known weight stood on it. It was found that
the constant was 770 lb/ft.
Calculated the
length of time of impulse load contact for a "typical" 165 lb. person
running on a rebounder, and on a wooden board track where the constant was 33,000
Lb./ft. The time of contact is inversely proportional to the impact force. The
calculated times of contact were .13 seconds for the rebounder and .02 seconds
on the wooden board track.
Since .02 is only
about 15% of the .13, the maximum impact force on the rebounder would be only
1/6th that of the wooden board track.
One of the major
problems runners have is structural damage caused by the constant pounding of
the skeleton against unforgiving surfaces.
Peter Daetwiler
of Hong Kong, an executive of a hotel chain,was a runner who needed weekly cortisone
shots in his knee to combat the pain and swelling before he was turned on to
rebound exercise. He was then able to maintain his level of cardiovascular endurance
in the safety and convenience of his home in less time, and without the expensive
and painful medication.
