Bears are to be respected. They will run away from you if they have time. However, if you frighten them, surprise them or corner them, they will defend themselves very well! They can run faster than us and have very sharp powerful claws!
There is no point climbing trees to get away from bears! This bear is about the same height as me but heavier - more fat and fur.
I've seen a bear (probably them same one - they are territorial), while out running, three times.
I now carry a bear bell, which jingles as a run, to warn the bear of my approach. It gives them time to prepare to run away if we spot each other. One time I ran to a spot and turned around to return home along the same trail. I hadn't seen any bears so was more relaxed in running back, but within 2-3 minutes I ran into a bear. Well, we saw each other 10 metres apart. He must have been just off the track and waited quietly until I had run past before crossing the track!
This is what our local bear thought of me when he came onto our property during the night to feed off the apple tree only to find that I had already picked all the apples!