I know this problem very well. But I realized that it is not related to Hive account@actifit counting your steps... actually what happens is that, when you run, your stride or distance between steps is longer than when you walk so, for instance, when I run I used to have an stride of 1.5m which means I just need less than 6000 steps to reach 8km...
And if you run faster you will get still less steps 😂😂