Energy Estimates for Exercise
Working out just how much energy you used while exercising isn't always easy, especially since you can't really measure your start energy level and your final energy level. Some estimation is required. The good news is that scientists have done the hard work for us and worked out the equations needed to estimate the energy use for some exercises.
Where are my kcal?
The equations here give results in watts, in other words in the units of power, and power is energy over time. kcal (kilo-calories) are simply an energy measure. The total calories burnt therefore requires us to know for how long the power was applied (how much time was spent exercising).
kcal = (p * t) / 4185.8
p = power (watts) t = time (s)
Walking
Pandolf Equation:
M = 1.5W + 2.0(W + L)(L/W)^2 + η(W + L)(1.5V^2 + 0.35VG)
M = Metabolic Rate (watts)
W = Nude body weight (kg)
L = Load (clothing + equipment), kg
η = terrain factor (1.0 = treadmill)
V = walking velocity (m/s)
G = Grade (%) 0% = flat surface
Source: Pandolf, K. B., Givoni, B., Goldman, R. F. (1977). Predicting energy expenditure with loads while standing or walking very slowly. J. Appl. Physiol.: Respirat. Environ. Exercise Physiol. 43(4): 577-581, 1977
Running
The following equation is more accurate for speeds in excess of 2.2 m/s (7.2 km/h), i.e. running speeds.
Mr = Mw - 0.5(1 - 0.01L)(Mw - 15L - 850)
Where Mw = result of Pandolf Equation
Source: K. B. Pandolf et al., Predicting metabolic cost of running with and without backpack loads, J. European Journal of Applied Physiology, Volume 56, Number 5 / September, 1987
