Incline is no joke. Anyone who’s tried walking alone on an incline for 30 minutes alone will understand the challenges of it, let alone running uphill. If you’re running on an incline on a treadmill, the in-built calorie counter can help calculate your energy expenditure while accounting for the steepness of the incline. You can then compare the caloric percentage difference induced by varying elevation as opposed to complete flatness. This acts as a decent gauge for running on incline outdoors. When running outside, however, online calorie calculators should be taken as estimates because unless you’re certain about the exact incline grade of the hill, the data won’t be most accurate.
With that being said, the type of running surface often goes in conjunction with incline. Depending on the surface texture, the amount of caloric expenditure can also differ accordingly. For example, treadmill running is relatively easier than outdoor running due to the lack of wind resistance or path obstructions. Conversely, running outdoors includes a multitude of hindrances like muddy and rocky trails as well as natural path undulation. As a result, the energy required to overcome these obstacles while maintaining running pace and posture definitely requires more effort.