While drawing diagrams to calculate it would be fun, have you considered comparing your heart rate with and without the stroller?
That would be a much more reliable than trying to estimate the increased energy requirements. Here's why:
We would need to calculate the friction the stroller has ...
Here's a nice example of a similar question
if you want to know how much energy you use, measure it
A mixed model was used to derive the following equation for predicting physical activity energy expenditure (EE): EE = -59.3954 + gender x (-36.3781 + 0.271 x age + 0.394 x weight + 0.404 V[O.sub.2max] + 0.634x heart rate) + (1 - gender) x (0.274 x age + 0.103x weight + 0.380x V[O.sub.2max] + 0.450 x heart rate) where gender = 1 for males and 0 for females.
I'm going on a holiday for three weeks and since Nathan is fairly busy at work, Greg needs your help to moderate the site.
So to anyone with 500+ rep: vote to close questions when they are off-topic, not constructive or are generally poor.
Even if you don't have 500 rep, you can always flag qu...