Hiking + Running?

fluffykitsune

Today I took my dogs for a 8 mile hike with a 3,000 altitude gain, but I forgot that tonight was my run night. Is it safe to double up or should I hold off on my run until tomorrow? I'm not sore currently but while we were going up I could feel it in my calves. I don't want to hurt myself.

Also, how much of a difference do backpacks make? I take my pack and it usually weighs 15lb (four dogs + running around = lots of water and treats!)
When I take my pack I have to stop for breaks sometimes, I get out of breath easily, but without it I can power through. Is it working muscles .. ? Would it be worth it to slowly add more weight ?