True CS 1.0 Owner's Manual page 58

Appendix C
True treadmills use the calorie expenditure formula as described
in Guidelines for Exercise Testing and Prescription from the
American College of Sports Medicine. This is the most widely
accepted formula for running and walking.
The ACSM guide says that running burns calories twice as fast
as walking, e.g., a 150-pound person jogging at 5 mph requires
548 calories per hour, while walking at 5 mph requires 274 per
hour.
(Other respected researchers such as David Costill think the
ACSM overstates the energy difference between running and
walking. Costill believes running requires
60% more energy than walking, not 100%
as calculated by the ACSM. Using the same
example, Costill's calculations result in 496
cal/hour for running 5 mph, with 313 cal/hour
for walking 5 mph.)
One potential source of calorie estimate error
is that the treadmill doesn't know if you are
running or walking, so it has to make some
assumptions. It assumes you are walking at 3 mph and slower,
and running at 5 mph and faster. Between those two speeds, the
treadmill combines the walking and running formulas to make
its best guess.
Variations in human exercise efficiency are another potential
source of error, with differences of plus or minus 20% common
in the population.
56
CS1.0 Treadmill Owner's Guide
A Note
About
Calorie
Expenditure
Calculations